Speciality
Spotlight

 




 


Ophthalmology


 

 





Glaucoma

   

  • K
    Strenn, B Matulla, M Wolzt, et al (Univ of Vienna)

    Reversal of
    Endothelin-1-induced Ocular Hemodynamic Effects by
    Low-dose Nifedipine in Humans.

    Clin
    Pharmacol Ther 63:54-63, 1998

      

    Calcium
    channel blockers may be beneficial in patients with
    normal-tension glaucoma and vasospastic reactions.
    Calcium channel blockers (CCB) may increase
    ocular-blood flow and have a functional antagonism
    with endothelin-1 (ET-1) in the ocular vasculature.

      

    Nifedipine
    reverses ET-1 induced constriction in ocular
    vasculature at doses that do not affect systemic
    hemodynamics. This
    suggests some association between the therapeutic
    effect of CCBs and the endothelin system in patients
    with normal tension glaucoma.

      

    The
    above findings provide a rationale for studying
    low-dose nifedipine as a supplementary medication in
    patients with glaucoma.

        

  • S
    Beatty, PA Good, J McLaughlin, et al (Birmingham and
    Midland Eye Centre, Birmingham, England).

    Echographic
    Measurements of the Retrobulbar Optic Nerve in
    Normal and Glaucomatous Eye.

    Br J Ophthalmol 82:43-47, 1998.

      

    The
    authors used a new-generation B scanner to measure
    orbital optic nerve dimension in eyes with glaucoma
    and ocular hypertension.

      

    49
    patients with glaucoma and 90 controls were studied.
    Five repeated echographic measures of the
    maximal interpial diameter and cross-sectional area
    of the orbital optic nerve were obtained in 1 eye of
    each participant on two occasions.

      

    Eyes
    with glaucoma were found to have reduced optic-nerve
    interpial diameter and cross-sectional areas,
    indicating nerve-fibre loss.
    This method would be of special value in
    differentiating normal from glaucomatous eyes when
    optic-disc morphometry is not possible because of
    opaque media.

      

  • WL
    Membrey, DP Poinoosawmy, C Bunce, F W Fitzke, R A Hitchings (Moorfields Eye Hosp, London)


    Comparison of visual field progression in patients with normal pressure glaucoma between eyes with and without visual field loss that threatens fixation.



    BJO 2000; 84: 1154-1158.


      


    A large number of eyes (over 60%) without prior field loss, fail to demonstrate progressive visual field damage over a long follow up period. It is recommended that normal pressure glaucoma patients be monitored for progression and that potentially harmful therapy be withheld until progression is demonstrated.

      


    The presence of visual field loss that threatens fixation, does not necessarily constitute an increased risk of field progression. However, it does indicate an increased risk of further field loss close to fixation resulting in loss of central acuity.

      


    Hence, patients with visual field loss that threatens fixation need to be managed more aggressively.

      

  • Changwon
    Kee, Seong-Heon Moon. (Dept. of Ophthalmology, Samsung Medical Center College of Medicine, Seoul).


    Effect of cataract extraction and posterior chamber lens implantation on outflow facility and its response to pilocarpine in Korean subjects.



    Br.J Ophthalmol, 2000: 84: 987-989.


       


    Intraocular pressure was measured by Goldmann applanation tonometer in 42 patients with cataracts and outflow facility was measured by tonography preoperatively, before and after pilocarpine installation.

      


    All patients were operated by the same surgeon using clear corneal phaco-emulsification and a silicone foldable I.O.L. implantation within the bag.

      


    Two months after surgery, slit lamp examination, gonioscopy were performed and IOP and outflow facility were estimated.

      


    The statistical analysis carried out by the authors reveal that lens extraction causes a reduction in IOP and an increase in outflow facility in Korean subjects.

      


    Pilocarpine causes an increase in outflow facility which persists after cataract extraction and posterior chamber lens implant.

      

  • M la Cour, J F Kiilgaard, T Eysteinsson, et al (Univ of Copenhagen, Denmark; Univ of Iceland, Reykjavik, Iceland)


    Optic Nerve Oxygen Tension: Effects of Intraocular Pressure and Dorzolamide.



    Br.J. Ophthalmol 2000; 84:1045-1049


      


    The aim of this experimental exercise was to evaluate the influence of acute changes in intraocular pressure (IOP) in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500mg of dorzolamide (carbonic anhydrase inhibitor).

      


    In domestic pigs, oxygen tension was measured by means of a polarographic electrode in the vitreous 0.5mm anterior to the optic disc. This entity is called the optic nerve oxygen tension.

      


    It was found that intravenous administration of 500mg dorzolamide increases the oxygen tension at the optic nerve head during acute increases in I.O.P

      

  • D
    Siriwardena, A Kotecha, D Minassian, et al (Institute of Ophthalmology, London)


    Anterior chamber flare after trabeculectomy and after phacoemulsification.



    Br. J.Ophthalmol 2000; 84: 1056-1057.


       


    This study of 131 consecutive patients was undertaken to evaluate and compare prospectively anterior chamber (a.c.) flare after phacoemulsification cataract extraction and after trabeculectomy with peripheral iridectomy.

      


    None of the patients had a history of pseudoexfoliation, uveitis or previous ocular surgery. It was found that a.c. inflammation and breakdown of the blood-aqueous barrier was much more prolonged after uncomplicated small incision cataract surgery than after glaucoma filtration surgery with peripheral iridectomy.

      


    This prolonged low grade inflammation is likely to be due to release of lens crystallins and lens epithelial cells into the aqueous humour, the effect of ultrasound, and/or the high volume of fluid passing through the eye at the time of surgery. 

      


    The above factors may increase the production of fibrogenic cytokines in the aqueous humour of patients who undergo phacoemulsification. 

      


    This may explain why the success rate of phaco-trabeculectomy is significantly lower than trabeculectomy alone. It may also explain why recent cataract surgery is a risk factor for failure of filtration surgery.

      

  • Oliver
    Arend, Andreas Remky, et al (Department of Ophthalmology, Germany, Department of Ophthalmology, Indiana University School of Medicine, USA)


    Altitudinal visual field asymmetry is coupled with altered retinal circulation in patients with normal pressure glaucoma.



    Br.J.Ophthalmol 2000; 84: 1008-1012


       


    Particularly in normal pressure glaucoma (NPG) disturbances of ocular circulation seem important in the pathogenesis of glaucomatous neuropathy.

      


    This prospective cross section study compared patients with NPG and altitudinal ASYMMETRIC perimetric findings between the superior and inferior hemisphere (group 1), 20 NPG patients with SYMMETRICAL field defects (group 2), and 18 healthy subjects.

      


    Fluorescein angiograms were done using a scanning laser ophthalmoscope. Using digital image analysis, arteriovenous passage time (AVP) and vessel diameters were assessed for comparison of corresponding affected
    and less arterial arcades.

      


    It was found that both affected and less affected hemispheres showed significantly prolonged AVP times when compared with healthy subject data.

      


    In hemispheres with more severe glaucomatous field loss, the AVP times were significantly prolonged, compared with the less affected hemisphere.

      


    The authors conclude that altitudinal visual field deficits are linked together with circulatory deficits of retinal tissue.

      


    The attentuated circulation seems to be a considerable factor in the natural course of
    glaucomatous optic neuropathy.

      

  • Rainer G, Menapace R, Schmetterer K, et al (Univ of Vienna)


    Effect of Dorzolamide and Latanoprost on Intraocular Pressure After Small Incision Cataract Surgery.


    J Cataract Refract Surg 25: 1624-1629, 1999.

      


    If there is elevated intraocular pressure (IOP) within 24 hrs. of cataract surgery, there may be a risk of developing corneal epithelial oedema, pain, retinal artery occlusion or anterior ischaemic optic neuropathy.

       


    In a study of 102 patients, it was found that both dorzolamide and latanoprost effectively reduced IOP rises after 6 hours. However only
    dorzolamide was of help after 20 to 24 hours.

      


    If untreated IOP rose about 5mmHg in 6 hrs and 1.5mm Hg within 24 hours. Using dorzolamide reduced the increase of IOP significantly. Latanoprost worked well only in the shorter term. Neither dorzolamide nor latanoprost could prevent IOP spikes of 30mm Hg or above.

          

  • Thoe Schwartzenberg
    GWS, Trope GE (Univ of Toronto)

    Anorexia, Depression and Dementia induced by Dorzolamide Eyedrops
    (Trusopt)

    Can J Ophthalmol 34: 93-94, 1999

       

    This is a case report of a patient with systemic adverse effects of topical
    dorzolamide.

       

    The case report highlights the importance of the awareness of side effects of all topical medications used for glaucoma.

        

  • N
    Naveh, A Kaplan-Messas, et al (Tel-Aviv Univ.School of Medicine, Sheba Medical Centre, Israel, and St.Thomas’s Hospital, London, UK)

    Mechanism related to reduction of intraocular pressure by melanocortins in rabbits.

    Br J Ophthalmol, 2000; 84: 1411-1414

       

    A single application of melanocyte stimulating hormone (MSH), caused a sustained dose related ocular hypotensive effect without any side effects.

       

    An increase in eicosanoid and cyclic AMP (cAMP) levels following exposure of iris, ciliary body (ICB) to MSH indicates their significance in MSH induced ocular hypotension.

       

    MSH and its analogues may have clinical relevance as antiglaucoma drugs with fewer side effects because of their antiallergic and anti-inflammatory properties.

       

  • G Rainer, Rupert Menapace, Oliver Findl, et al (Univ. of Vienna, Austria)

    Intraocular pressure rise after small incision cataract surgery: a randomised intraindividual comparison of two dispersive viscoelastic agents.

    Br.J. Ophthalmol. Feb.2001, 85: 139-142.

      

    This study (prospective and randomized) comprised 80 eyes of 40 consecutive patients who had bilateral small incision cataract surgery. Phacoemulsification was done after a 3.2mm sutureless incision and a foldable silicone intraocular lens was inserted.

      

    The patients were randomly assigned to receive OCUCOAT (hydroxy-propyl methylcellulose 2%) or viscoat (sodium chondroitin sulphate 4% – sodium hyaluronate 3%) for the first eye operation. The second eye which was operated later received the other viscoelastic agent.

       

    It was found that VISCOAT causes a significantly higher intraocular pressure (IOP) increase and significantly more IOP spikes thank OCUCOAT in the early postoperative period.

       

  • T Manners, J F Salmon, A Barron, et al (Groote Schuur Hospital, Cape Town, South Africa)

    Trabeculectomy with mitomycin C in the treatment of post-traumatic angle recession glaucoma.

    Br J Opthahlmol, Feb.2001, 85: 159-163.

       

    Traumatic angle recession is a risk factor for failure of glaucoma filtration surgery. This study is a retrospective analysis of 43 consecutive trabeculectomy procedures in 41 patients followed for a mean period of 25 months.

       

    Mitomycin C 0.02% was applied between the sclera and conjunctiva for one to five minutes at the time of surgery.

       

    The authors found trabeculectomy with mitomycin C application, an effective surgical procedure. There was good intraocular pressure control and most cases had good preservative of vision.

       

  • A
    Sciscio, Anthony G Casswell, (Sussex Eye Hospital, Brighton, UK)

    Effectiveness of apraclonidine 1% in preventing intraocular pressure rise following macular hole surgery.

    Br. J Ophthalmol. Feb.2001, 85 : 164-168.

       

    Twenty-six eyes (of 25 patients) were studied in a prospective, double masked, randomised study, to compare apraclonidine hydrochloride 1%, an A2 agonist (12 eyes) with a placebo (14 eyes) in the prevention of intraocular pressure (IOP) spikes following macular hole surgery.

      

    Macular hole repair surgery was performed with a vitrectomy, platelet adjunct, and complete fill of the vitreous cavity with perfluoropropane gas (C3F8) at a concentration of 16%.

       

    It was found that apraclonidine hydrochloride 1% was efficacious and safe in the prophylaxis of early IOP spikes in patients undergoing macular hole
    surgery.

       

  • O.J.
    Lehmann, C. Bunce et at [Moorfields Eye Hospital, London, UK]

    Risk Factors for Development of post-trabeculectomy endophthalmitis.

    BJO 2000; 84: 1349-1353

       

    This article describes a case-control study performed on patient with post trabeculectomy endophthalmitis over a period of 6.5 years.

       

    The results provide strong evidence of an increased risk of late endophthalmitis in patient who have diabetes mellitus, patients with blebitis. Antiproliferative agents may also have a significant role towards increasing the risk.

        

  • Ahmed M Abu, EI-Asrar, Sofie Struyf et al [King Saud Univ, Riyadh, Saudhi Arabia]

    Chemokines in the Limbal Form of Vernal Ketatoconjunctivitis 

    BJO 2000; 84: 1360-1366

       

    Chemokines are a family of low molecular weight cytokines that attract and activate leucocytes. The CC chemokines play an important part in allergic diseases.

        

    The aim of the study was to investigate the expression of CC chemokines, in the conjunctiva of patients with vernal keratoconjunctivities.

       

    The results demonstrated a definite increase in the expression of chemokines in the conjuctiva of patients with vernal keratoconjunctivities [VKC] suggesting a potential role for chemokines in the pathogenesis of VKC.

       

    Antagonists of chemokine receptors may provide new therapeutic modalities in
    VKC.

        

  • KRG Martin, DC Broadway (West Norwich Hosp. UK)

    Cyclodiode Laser Therapy for Painful Blind Glaucomatous Eyes

    Br.J Ophth 2001: 85; 474-476



    Cyclodiode laser treatment was found to be very effective in eliminating discomfort in painful, blind glaucomatous eyes.



    The best predictor of successful pain relief was intraocular pressure reduction more than 30% from the base line.



    Protocols using slightly less total energy delivery to the ciliary body might have a lower risk of hypotony but in such cases retreatment may be required.

       

  • W
    Birchall, V Kumar (Royal Eye Hosp., Manchester and Stepping Hill Hospital, Stockport UK)

    A Comparative study of proxymetacaine – fluorescein and lignocaine – fluorescein use during applanation tonometry

    Br J Ophthal 2001; 85, 477-479



    This article analyzed the results of a randomized masked, double-blind prospective study of 60 consecutive patients, assessing the duration of the stinging sensation, degree of discomfort, the extent of
    reflex lacrimation, the need for subsequent tear film manipulation, and total time to complete tonometry.



    Proxymetacaine fluorescein (PROX- FLU) caused significantly less discomfort and reflex lacrimation than lignocaine fluorescein
    (LIG-FLU). Accurate tonometry was more rapidly completed when PROX-FLU was used. PROX-FLU was preferred by 98% of study patients.

       

  • K. Miyake, I Ota et al (Chiba Hokuso Hospital, Nippon Medical School, Chiba; and Kushimoto Rehabilitation Center Wakayama, Japan)

    Enhanced Disruption of the Blood-Aqueous Barrier and the Incidence of Angiographic Cystoid Macular Edema by topical Timolol and its preservative in Early Postoperative Pseudophakia

    Arch.of Ophth. Vol.119, March 2001, p.387-394.



    Timolol and its preservative, benzalkonium chloride, cause disruption of the blood aqueous barrier in early postoperative pseudophakia, along with increased incidence of angiographic cystoid macular edema (CME).



    The concurrent administration of diclofenac prevents these adverse effects without any effect on the fall in intraocular pressure.



    The presence of benzalkonium chloride contributes considerably to these adverse effects of timolol.

      

  • P.R.
    Egbert, S. Fiadoyor et al (Stanford Univ. Ca; Cape Coast Ghana; Bascom Palner Eye Inst. Miami, Fla)

    Diode Laser Transcleral Cyclophotocoagulation as a Primary Surgical Treatment for Primary Open-angle Glaucoma.

    Arch.Ophthal, Vol.119, March 2001, p.345-350.

       

    This study was undertaken in 92 patients, to evaluate the feasibility of diode laser transcleral cyclophotocoagulation (TSCPC) as a primary treatment for open-angle glaucoma and to compare two laser energy settings.



    It was found that diode laser TSCPC is a practical rapid well-tolerated procedure providing a modest but variable lowering of intraocular pressure. The only complication in some cases was an atonic pupil. Moderate variation in laser energy settings does not influence the results.

       

  • RE
    Warwar, JD Bullock, D Ballal (Wright State Univ, Dayton, Ohio) 

    Cystoid Macular Edema and Anterior Uveitis Associated with Latanoprost Use: Experience and Incidence in a Retrospective Review of 94 patients. 

    Ophthalmology 105: 263-268, 1998.

       

    Latanoprost, a prostaglandin analogue, is the first of a new class of drugs developed to reduce intraocular pressure.

       

    Out of 94 patients and a total of 163 eyes reviewed anterior uveitis developed in 6.4% of the patients and in 4.9% of all eyes during latanoprost treatment. CME occurred in 2.1% of patients and in 1.2% of all eyes.

      

    Clinicians need to be aware of these possible complications when using latanoprost.

       

  • O
    Cekic, C Batman (SSK Ankara Eye Hosp, Turkey)

    Effect of Capsulorrhexis Size on Postoperative intraocular pressure.

    J Cataract Refract Surg 25: 416-419, 1999

       

    The possible effect of capsulorrhexis size on intraocular pressure (IOP) was prospectively examined in 58 eyes of patients undergoing clear corneal phacoemulsification with IOL implantation.

      

    It was found that a 4mm capsulorrhexis produced a lower postoperative IOP compared with a 6mm
    capsulorrhexis.

      

    Editorial comments on the above article:

        

    Though a large capsulorrhexis makes it easier to mobilize the nucleus and to place the IOL within the capsular bag, there are several disadvantages of this large capsulorrhexis.

    (1) IOL fixation is not stable (2) Greater chances of iridocapsular synechia (3) Unwanted optical images from edge glare effect because of the overlying of the capsulorrhexis on the lens optic.

       

    The authors speculate on several reasons as to why a smaller capsulorrhexis may produce a lower postoperative IOP, than a larger capsulorrhexis. In patients with anterior capsule contraction syndrome, it is often observed that they have a low IOP and after YAG laser capsulotomy the IOP will rise.

        

  • Hedner J, Everts B, Strom Moller C
    (Sahlgrenska Univ, Goteborg, Sweden; Pharmacia & Upjohn, Stockholm)


    Latanoprost and Respiratory Function in Asthmatic Patients Randomized Double-Masked, Placebo-controlled Crossover Evaluation.


    Arch Ophthalmol 117: 1305-1309, 1999

      


    ß-receptor antagonist agents used to treat glaucoma may adversely affect the patient’s respiratory disorder. The possible effect of
    latanoprost, on respiratory function, especially of patients with asthma who have not previously taken
    corticosteroids, was investigated.

      


    Latanoprost treatment produced no alterations in resting or provoked airway function, or in asthma symptoms, in this group of patients who had not used corticosteroids previously.

        

  • Rasheed ES (El Maghraby Eye
    Ctr, Madina)


    Initial Trabeculectomy with Intraoperative Mitomycin-C Application in Primary Glaucomas


    Ophthalmic Surg Lasers 30: 360-366, 1999.

      


    Mitomycin C is an alkylating agent acting at all stages of the cell cycle. It reportedly inhibits fibroblast proliferation by preventing DNA synthesis, thereby decreasing the amount of scar tissue formation after
    trabeculectomy.

      


    The authors conducted a randomized study which compared the overall efficacy of the intraoperative application of Mitomycin C. They found that the use of intraoperative Mitomycin C may increase the success rate of glaucoma surgery. They felt that close follow-up and meticulous patient management are required, especially in the early post-operative period.

      


    Complications described are those that occur immediately postoperatively, related primarily to excessive filtration. Eyes with an overfiltering or leaking bleb are often uncomfortable to the patient. Vision is blurred due to low pressure and the excessive moisture on the corneal surface and the patient may suffer from photophobia.

      


    The late complications can be endophthalmitis, blebitis and
    hyptomy.

       

  • A
    Raihan, Sekhat GC, Naduvilath TJ, et al (LV Prasad
    Eye Inst, Hyderabad, India)

    The Role of Tenonectomy in Trabeculectomy

    Indian J Ophthalmol 47: 117-119, 1999

      

    The effects of tenonectomy in reducing IOP during
    trabeculectomy were retrospectively reviewed.

      

    Tenonectomy appears to reduce not only mean IOP but
    also increases the percentage of patients reaching a
    target IOP of 14mm Hg.

      

    Editorial comments on the above article:

    The editor rarely does a tenonectomy and does not
    plan to start doing it routinely.

      

    The purposes of glaucoma surgery are :

    (1) To lower IOP

    (2) To prevent visual field loss

    (3) To protect the optic nerve from glaucoma damage

    (4) To enhance the health of the patient

    (5) To relieve pain

    (6) To develop a filtering bleb.

      

    It is not known whether it is the AMOUNT of
    pressure-lowering or the STABILITY of
    pressure-lowering that is the critical aspect. If
    the pressure is lowered precipitously, surgery is
    more likely to be associated with a super choroidal
    expulsive haemorrhage. Pressure lower than 10mm Hg
    may lead to deterioration of vision caused by
    unstable refractive error, or in rarer cases,
    choroidal folds in the macular oedema. 

      

    The younger, the more myopic and the less damaged
    the optic nerve, the more likely is the low pressure
    to be associated with macular oedema.

      

    There is evidence that an IOP below 10mm Hg
    predisposes to retinal vein occlusion or even to
    more rapid progression of field loss.

      

    The health of the patient is enhanced by preventing
    visual field loss and avoiding the side effects of
    treatment.

      

    Tenonectomy may be appropriate to perform in
    selected cases when a low IOP is desired and the
    problem of a thin filtering bleb is of not much
    concern.

      

  • Jacobi
    PC, Dietlein TS, Krieglstein Gk (Univ Eye Hosp
    Cologne, Germany)

    Goniocurettage for Removing Trabecular Meshwork:
    Clinical Results of a New Surgical
    Technique in Advanced Chronic Open-Angle Glaucoma.


    Am J Ophthalmol 127: 505-510, 1999

      

    Goniocurettage may deal more directly with the area
    of resistance to aqueous outflow. The procedure is
    carried out with an instrument resembling a
    microchalazion curette. The curettage removes
    trabecular tissue from the angle.

      

    The authors evaluated the procedure in 25 eyes of
    patients who had had unsuccessful filtering
    procedures for chronic open angle glaucoma and found
    that goniocurettage controlled intraocular pressure
    over a lengthy period of time. Patients who have
    excessive conjunctival scarring may benefit from
    this procedure.

      

  • Kosmin
    AS, Wishart PK (Royal Liverpool Univ, England)

    A Full-Thickness Scleral Graft for the Surgical
    Management of a Late Filtration Bleb Leak.

    Ophthalmic Surg Lasers 28: 461-468, 1997.

      

    Late bleb leak can occur months to years after
    filtration surgery. Eight leaking blebs were
    repaired, using a full thickness scleral graft. This
    procedure was effective, particularly for leaks
    associated with full thickness scleral defects.
    Inspite of IOP spikes occurring early in the
    postoperative period, long-term IOP control was
    usually achieved with no need for further filtration
    surgery.

       

  • Trible
    JR, Schultz RO, Robinson JC, et al (Med College of
    Wisconsin, Milwaukee)

    Accuracy of Scanning Laser Polarimetry in the
    Diagnosis of Glaucoma

    Arch Ophthalmol : 117: 1298-1304, 1999

      

    Improved methods of screening for glaucoma could
    decrease the degree of damage caused by the disease.

      

    Patients with glaucomatous damage can be
    differentiated from those with normal findings using
    scanning laser polarimetry, but many cases with
    severe damage were missed with this method.

      

  • Salgarello
    T, Colotto A, Falsini B, et al (Catholic Univ, Rome)

    Correlation of Pattern Electroretinogram with
    Optic Disc Cup Shape in Ocular Hypertension.

    Invest Ophthalmol Vis Sci 40: 1989-1997, 1999

      

    The pattern electroretinogram (PERG) provides an
    index of inner retinal function. The correlation of
    PERG findings and confocal scanning laser
    ophthalmoscopy in ocular hypertension (OHT) was
    investigated.

      

    It was found, (in a study of 34 patients with OHT)
    that the shape of the optic disc cup, is
    significantly, though weakly, correlated with PERG
    amplitude. Hence the authors postulate that combined
    PERG and optic disc cup structural analysis (with
    confocal scanning laser ophthalmoscopy) may be of
    diagnostic value for detecting early damage to the
    optic nerve head in patients with OHT.

       

    Editorial comments on the above article:

    Standard electroretinography with a flash that
    illuminates most of the fundus, picks up glaucoma
    damage, only when it is advanced.

      

    The PERG, which is able to isolate localized areas
    of the retina more specifically, is theoretically
    more likely to detect early glaucoma defects.

      

    However, there is no convincing evidence to date
    that those patients in whom PERG noted a defect, are
    patients who WILL have progressive glaucomatous
    nerve damage. Nor is there any evidence that those
    in whom PERG results are normal will NOT have
    glaucomatous damage in future.

      

    Multifocal electroretinogram (ME) which stimulated a
    more localized area of the retina may be more
    accurate than PERG, but studies with ME are even
    more preliminary.

       

  • Shareef
    S, Sawada A, Neufeld AH (Washington Univ, St. Louis)

    Isoforms of Nitric Oxide Synthase in the Optic
    Nerves of Rat Eyes with Chronic Moderately Elevated
    Introcular Pressure.

    Invest Ophthalmol Vis Sci 40: 2884-2891,
    1999.


      

    Nitric oxide synthase (NOS) contributes to the
    formation of Nitric Oxide (NO) from L-arginine. Rat
    CNS demonstrates 3 NOS isoforms, but rat eyes are
    devoid of NOS.

      

    The isoforms NOS-1 and NOS-3 are found in NORMAL
    human optic nerve heads. All 3 isoforms have been
    noted in the optic nerve head of patients with
    primary open-angle glaucoma.

      

    After cautery of 3 episcleral vessels, unilateral
    raised intraocular pressure (IOP) was produced in
    rats.

      

    Rat eyes that had elevated IOP because of cautery,
    had no detectable changes in NOS-1 and NOS-3, but
    NOS-2 was noted in the astrocytes of the optic nerve
    heads and remained for upto 3 months.

      

    The authors concluded that when there is chronic
    moderately elevated IOP, NOS-2 appears in astrocytes
    and may contribute to the neurotoxicity of retinal
    ganglion cells.

       

    These findings may have implications for the choice
    of pharmacologic agents used to treat glaucoma.

        

  • JH
    Gurwitz, SM Yeomans, RJ Glynn, et al (Meyers Primary Care Inst, Worcester, Mass; Univ of Mass, Worcester; Harvard Med School, Boston)

    Patient Noncompliance in the Managed Care Setting: The Case of Medical Therapy for Glaucoma

    Med Care 36: 357-369, 1998.

        

    Accurately identifying which patients are most likely to be noncompliant is still a challenging task. Demographic and clinical characteristics associated with noncompliance in patients beginning medical treatment for glaucoma in a managed care setting were studied retrospectively.

        

    Out of 616 patients, 152 (24.7%) met the criteria for noncompliance. During the one year study, the mean number of days without treatment was 103.9, compared with 6.8 for those categorized as compliant. 

    The variable most strongly associated with non-compliance was fewer visits to an ophthalmologist. Identifying who would likely to be noncompliant using demographic and clinical data remains difficult.

        

  • PJ Foster, J Baasanhu, PH Alsbirk, et al (Inst of Ophth. London; Med. Univ, Ulaanbaator Mongolia; Hillerod Hosp, Denmark)

    Central Corneal Thickness and Intraocular Pressure in a Mongolian Population.

    Ophthalmology 105: 969-973, 1998.

        

    Differences in central corneal thickness (CCT) have been shown to affect tonometric estimates of IOP. Correlation between IOP measurements and CCT was studied in 1244 residents of a Mongolian town.

        

    The collected data suggested that variations in CCT account for changes in IOP estimates. When the additional effect of age on CCT is considered, even more variation in IOP can be accounted for by CCT.

         

  • RS
    Rubinfeld, EJ Cohen, PR Laibson, et al (Wills Eye Hosp, Philadelphia)

    The Accuracy of Finger Tension for Estimating Intraocular Pressure After Penetrating Keratoplasty.

    Ophthalmic Surg Lasers 29:213-215, 1998.

        

    Goldmann tonometry, if used immediately after a penetrating keratoplasty (PK), is not an accurate estimate of intraocular pressure (IOP).

        

    The finger tension method for estimating IOP after PK can be useful. Its utility relies on proper technique and the absence of lid oedema.

        

  • YH
    Yucel, N Gupta, MW Kalichman et al (Univ of California, San Diego; Univ of Toronto; Allergan Inc, Irvine, Calif)

    Relationship of Optic Disc Topography to Optic Nerve Fiber Number in Glaucoma.

    Arch Ophthalmol 116:493-497, 1998.

       

    Measures of optic-disc topography were compared with the number of surviving optic-nerve fibres in glaucoma. 

       

    Ten monkeys with laser induced glaucoma in the right eye were studied. A confocal scanning laser ophthalmoscope was used to measure optic-disc topography in vivo. Histomorphometry was done on optic-nerve cross-sections, using bright-field microscopy with camera lucida.

       

    Most optic-disc topography measures were significantly associated with the number of optic-nerve fibres. The data support the use of confocal scanning laser ophthalmology to assess optic-nerve damage in glaucoma.

        

  • ST
    Hoh, DS Greenfield, JM Liebmann, et la (The New York Eye and Ear Infirmary; New York Med College, Valhalla; Singapore Eye Research Inst; et al ) 

    Factors Affecting Image Acquisition During Scanning Laser Polarimetry. 

    Ophthalmic Surg Lasers 29: 545-551, 1998.

        

    Scanning Laser Polarimetry (SLP) is a noninvasive technique, which enables quantitative measurement of peripapillary retinal-nerve fibre layer (RNFL) thickness. Artifacts which may be observed during RNFL measurement with SLP, were described.

        

    Four hundred and twenty six patients were reviewed.

       

    Anterior and posterior segment abnormalities, especially those localized to the cornea and lens, may cause spurious RNFL measurements.

       

    According to recent reports, there is a co-relation between the appearance of the optic nerve and nerve-fibre layer as determined by HEIDELBERG Retinal Tomography, and the number of neurons present. Hence it may be possible to get an idea of glaucoma damage by estimating nerve fibre layer thickness. However, there are differences between reproducibility and validity. It is important to realize that there are still many hazards to using image-analysis techniques.

        

  • Lill-Inger Larsson, (Uppsala Univ. Hospital, Uppsala, Sweden)

    Aqueous Humor Flow in Normal Human Eyes Treated with Brimonidine and Timolol, Alone and in Combination.

    Arch Ophthalmol, April 2001; vol.119, pg.492-495

      

    Topically applied 2% brimonidine tartrate was compared with topical 0.5% timolol maleate alone, and in combination, in a randomized, double-masked, placebo-controlled study of 20 human subjects.

       

    Brimonidine reduced aqueous humor flow by 33.1%, timolol by 49.9%, and the combination of brimonidine and timolol by 58.9%. Brimonidine reduced the IOP by 20.3%, timolol by 22.9%, and the combination by 34.7%.

       

    The results of this study indicate that brimonidine suppresses aqueous humor formation, but not as efficiently as timolol.

       

    When timolol and brimonidine were applied in combination a further reduction of aqueous humor flow and IOP was seen.

      

    Evidence supports the theory that brimonidine has some additional ocular hypotensive effect through enhancement of aqueous outflow.

       

  • R A Laibovitz, A M VanDenburgh, et al (Eye Research Associates, Austin, Texas and Allergan Inc. Ophthalmology Clinical Research, Irvine, Calif.)

    Comparison of the Ocular Hypotensive Lipid AGN 192024 with Timolol.

    Dosing, Efficacy and Safety Evaluation of a Novel Compound for Glaucoma Management.

    Arch.Ophthal, vol.119, July 2001, pp.994-1000

       

    This article analyses a 30-day, randomized investigator-masked, clinical trial involving 100 patients with raised intra-ocular pressure (IOP), to compare the safety and efficacy of the ocular hypotensive lipid AGN 192024 (Lumigan) with timolol.

       

    It was found that a dosage of 0.03% AGN 192024 once daily, lowered IOP significantly more than timolol and provided better diurnal IOP control.

       

    Twice-daily dosage of AGN 192024 was of no significant benefit over once a day usage.

        

    AGN 192024 was safe, well tolerated and provided superior ocular hypotension and diurnal IOP control, compared with
    timolol.

       

  • P.Demailly, C Allaire, C Trinquand, for the Once-daily Carteolol Study Group (Laboratories Chauvin, Montpellier, France)

    Ocular hypotensive efficacy and safety of once daily carteolol alginate


    B.J.O. Aug.2001; 85: 921-924




    This was a double masked, multicentre study of patients with ocular hypertension or open angle glaucoma, randomly assigned to receive either carteolol alginate four times a day or standard carteolol twice a day.



    It was found that the new alginate formulation of carteolol 2% administered once daily was as effective as standard carteolol 2% given twice a day. There were no meaningful differences regarding safety.

       

  • A
    Kotecha, D Siriwardena, et al (Institute of Ophthalmology and Moorfields Eye Hospital, London, UK)

    Optic disc changes following trabeculectomy: longitudinal and localization of change.

    Br. J. Ophthal, August 2001; 85: 956-961



    95 patients undergoing routine trabeculectomy (part of Moorfields/MRC 5-Fluorouracil trial) were recruited into this study.



    Eyes were imaged preoperatively with the Heidelberg retina tomograph (HRT, Heidelberg Engineering),, and at 3 months, 1 year, and 2 years after surgery.



    The predefined segment analysis available on the HRT analysis software was used to determine segmental change.



    .Intraocular pressure reduced with the passage of time. Maximum depth of cup reduced by the 3rd and 12th month.



    The authors conclude that reversal of disc cupping is present 2 years after trabeculectomy. The factor most influencing change is reduction of intraocular pressure. Segmental analysis showed that change in rim volume was maximal in the nasal, inferonasal, superonasal and superotemporal regions.

       

  • L Rojas, G Ortiz, et al (Bogota, Colombia)

    Ghost cell glaucoma related to snake poisoning 

    Arch Ophthalmol Vol. 119, August 2001 Pg. 1212-1213

       


    This is an interesting case report of a 44 year old male farmer who was examined in the emergency department of Hospital San Juan de Dios, National University of Colombia, Bogota, 72 hours after a snake bite (BOTHROPS ATHROX) in his right foot.

       


    The snakebite produced various manifestations

    1) Subconjunctival hemorrhage.

    2) Stromal and epithelial corneal edema. 

    3) Cells and flare in the anterior chamber.

    4) Vitreous hemorrhage.

    5) The intraocular pressure (IOP) was elevated in the left eye to 40 mm Hg.

    Two days after admission the patient complained of bilateral visual loss – hand movement in the right eye and light perception in the left eye. 

    6) Two weeks later, indirect ophthalmoscopy showed optic nerve pallor, and attenuated retinal vasculature.

    7) In the left eye a rhegmatogenous retinal detachment with macular involvement was seen.

        


    The authors postulate that vitreous hemorrhage leads to secondary glaucoma producing “ghost cell glaucoma” (GCG).

         


    Ghost cells (GCs) are degenerated spherical erythrocytes that partially lose their hemoglobin content by aging for a long time in the vitreous. Hemoglobin abandons the red blood cell and forms clumps that adhere to vitreous bands. Whatever hemoglobin remains in the red blood cell becomes denatured and binds to the internal surface of the cell membrane forming granules (Heinz bodies).

    Neither fresh red blood cell nor GCs can pass through an intact anterior hyaloid membrane, therefore a hyaloid injury must be present for these cells to be found in the anterior segment.

        


    Increased IOP usually occurs 2 to 4 weeks after the injury. This complication requires repeated lavage of the anterior chamber or vitrectomy to remove the hemorrhagic tissue. 

        


    GCG has been associated with diabetic vitreous hemorrhage without previous trauma or surgery as well as in other rare cases.

        


    Snake venoms especially from crotalids as in the case of BOTHROPS, contain proteolytic enzymes capable of breaking tissue proteins, thereby causing hemorrhage.

        


    Vipers venom alters vascular resistance as well as vascular integrity, alters coagulation mechanisms, and changes in the central nervous system, cardiovascular and pulmonary dynamics.

        


    Hyaluronidase, collagenase and other proteolytic enzymes present in the BOTHROPS venom may decrease the vitreous viscosity and alter the anterior hyaloid permeability which may allow migration of the GCs in the aqueous, leading to secondary glaucoma. 

         


    Ghost cells were identified by Papanicolaou stain.

        

  • Schwartz M, Yoles E (Weizmann Inst of Science, Rehovot, Israel)

    Self-Destructive and Self-Protective Processes in the Damaged Optic Nerve: Implications for Glaucoma

    Invest Ophthalmol Vis Sci 41: 349-351, 2000

      

    Degeneration in glaucoma is similar to that in any neurodegenerative disease in which disruptive forces emanating from the disease process, as a result of the primary insult, contribute to the self-propagating process of degeneration.

      

    The authors postulate that primary insult to the optic nerve awakens extra and intracellular processes, along with global immune mechanisms. Some of these processes are destructive, while others are beneficial and potentially capable of producing self-repair.

      

    One of the risk factors for glaucoma may be uncontrollable rise in the level of biochemical compounds such as glutamate and nitric acid which are triggered off by degenerating nerve. However, glutamate has an intermediate level at which it is not detrimental and, in fact, is even beneficial in triggering an intracellular mechanism of self
    defence.

      

    It is possible that endogenous T-cell immune response to optic nerve damage is beneficial, though limited.

      

    Accumulation of autoimmune T-cells may offer a source of neurotrophic factors, contributing to the self-repair mechanism.

        

  • Wax MB (Washington Univ, St.Louis)

    Is There a Role for the Immune System in Glaucomatous Optic Neuropathy?

    Curr Opin Ophthalmol 11: 145-150, 2000

      

    Autoimmune-mediated glaucoma injury appears to occur most often, though not solely, in patients whose intraocular pressure (IOP) has never been increased.

       

    Signal pathways of the immune system appear to regulate cell death in response to conditions that stress retinal neurons in glaucoma. Such conditions may include (i) Mechanical stress from high IOP (ii) ischemia (iii) excessive excitatory aminoacids (iv) toxic products resulting from excessive nitric acid synthase production in neurons or glial fibres surrounding the optic nerve.

        

  • Bradley
    JMB, Anderssohn AM, et al (Oregon Health Sciences Univ, Portland)

    Mediation of Laser Trabeculoplasty-Induced Matrix Metalloproteinase Expression by IL-1b and TNFa.

    Invest Ophthalmol Vis.Sci 41; 422-430, 2000

        

    Laser trabeculoplasty (LT) of the anterior uveal region of the trabecular meshwork results in sustained metalloproteinase expression in the juxtacanalicular area.

      

    The authors found that LT induces interleukin (IL)-1b and tumor necrosis factor (TNF)a expression and secretion during the first 8 hours after laser treatment.

       

    These cytokines, in turn, lead to increased trabecular stromelysin expression, which initiates remodeling of the juxtacanalicular extracellular matrix ( a likely site for aqueous outflow resistance), thus restoring outflow facility.

       

    However histopatologic studies have shown focal areas of superficial scarring of the trabecular meshwork. Further studies showed significant remodeling of the trabecular tissues following argon LT.

      

    Patients with increased pigmentation of the posterior trabecular meshwork are more likely to benefit from argon LT.

       

    Argon LT tends to work more effectively in elderly patients than those less than 40 yrs of age.

      

    It is imperative to use the minimum amount of energy in order to achieve beneficial effect on
    IOP.

            

  • Gross
    RL, Hensley SH, Gao F, et al (Baylor College of Medicine, Houston)

    Effects of Betaxolol on Light Responses and Membrane Conductance in Retinal Ganglion Cells.

    Invest Ophthalmol Vis Sci 41: 722-728, 2000

          

    The physiologic effects of betaxolol on retinal ganglion cells were investigated, and its potential to elicit neuroprotective response against retinal cell degeneration was determined, in an experiment where living retinal slice preparations of the larval tiger salamander were studied.

        

    The authors postulate that betaxolol prevents retinal ganglion cell death induced by increased extracellular glutamate or by increased spontaneous spike rates under pathologic conditions.

         

    Physiologic actions of betaxolol result in a decrease in neurotoxic effects in ganglion cells, which are most susceptible to glutamate-induced damage under ischemic and glaucomatous conditions.

         

  • Erickson KA, Schroeder A (Boston Univ.; New England College of Optometry, Boston).

    Direct Effects of Muscarinic Agents on the Outflow Pathways in Human Eyes

    Invest Ophthalmol Vis Sci 41: 1743-1748, 2000

           

    It was believed that muscarinic agonists bind to receptors in the ciliary muscle, causing contraction of the muscle, displacement of the scleral spur and widening of the spaces in the trabecular meshwork, facilitating aqueous humor outflow.

         

    However, recent studies have demonstrated that cells derived from human trabecular meshwork have muscarinic receptors.

          

    The authors studied whether muscarinic agonists could change outflow facility in perfused human ocular anterior segments, which did not have an intact ciliary muscle.

          

    Dissection and perfusion of human eyes was performed.

          

    Pilocarpine, aceclidine, or carbachol were added to the perfusion medium in 4 sequential concentrations. Outflow facility was measured for one hour after addition of each drug and compared with baseline measurements.

          

    The authors concluded that in human eyes, outflow facility is increased by muscarinic agonists by a direct stimulation of outflow tissues even in the absence of an intact ciliary muscle.

           

    An important observation was that outflow facility was better with LOWER concentrations, while higher concentrations had very little or no effect.

           

  • Selbach
    JM, Gottanka J, et al (Univ of Essen, Germany; Univ. of Erlangen-Nurnberg, Germany)

    Efferent and Afferent Innervation of Primate Trabecular Meshwork and Scleral Spur.

    Invest Ophthalmol Vis Sci 41: 2184-2191, 2000

          

    The authors investigated the correlation between nerve terminals and cells or extracellular matrix (ECM) components in different parts of the primate TM (trabecular meshwork) and scleral spur (SS).

          

    Serial sections through anterior segments of 10 monkey eyes and 12 human eyes were studied
    immunohistochemically.

           

    The authors found that the trabecular meshwork may have some ability to self-regulate aqueous humor outflow via cholinergic and nitrergic nerve terminals.

         

  • Karali A, Russell P, Stefani FH, et al (Univ of Erlangen-Nurnberg, Germany; NIH, Bethesda, Md; Univ of Munich, Germany)

    Localization of Myocilin/Trabecular Meshwork-Inducible Glucocorticoid Response Protein in the Human Eye.

    Invest Ophthalmol Vis Sci 41: 729-740, 2000

       

    Myocilin is also known as trabecular meshwork-inducible glucocorticoid response protein (TIGR). Distribution and cellular localization of myocilin/TIGR was evaluated in the human eye.

       

    Immunohistochemical analysis was carried out on 25 enucleated human eyes from patients with posterior choroidal melanoma as well as on 7 normal human donor eyes.

       

    Immunoreactivity for myocilin/TIGR was demonstrated in cells of the corneal epithelium and endothelial, and extracellularly in the corneal stroma and sclera.

       

    Positive staining was observed in cells of the uveal and corneo-scleral meshwork in the trabecular meshwork and area adjacent to Schlemm’s canal.

        

    Positive staining was also seen in cells of the ciliary epithelium, ciliary muscle, lens epithelium, stromal and smooth muscle cells of the iris and throughout the vitreous.

       

    The outer surface of rods and cones, neurons of both inner and outer nuclear layer, and axons of optic nerve ganglion cells also showed positive staining.

       

    The authors postulate that the presence of myocilin/TIGR in optic nerve axons as well as astrocytes of the lamina cribrosa, suggests that in GLC1A-linked open-angle glaucoma, the trabecular meshwork may not be the only target of abnormal
    myocilin/TIGR.

       

  • Ugurlu S, Hoffman D, Garway-Heath DF, et al (Univ of California, Los Angeles; Yale Univ, New Haven, Conn)

    Relationship Between Structural Abnormalities and Short-Wavelength Perimetric Defects in Eyes at Risk of Glaucoma

    Am J Ophthalmol 129: 592-598, 2000

        

    Detectable structural changes precede functional abnormalities detected with standard white-on-white static threshold
    perimetry.

       

    In this study, 72 patients at risk of glaucoma with normal white-on-white full threshold perimetry, underwent blue-yellow full threshold perimetry prospectively.

       

    In patients with ocular hypertension, clinically detectable structural abnormalities often co-exist with blue-yellow perimetric defects.

        

  • Doyle
    JW, Smith MF (Univ. of Florida, Gainesville)

    Effect of Phacoemulsification Surgery on Hypotony Following Trabeculectomy Surgery.

    Arch Ophthalmol 118: 763-765, 2000

       

    Chronic hypotomy is a frustrating complication following the use of local antimetabolites in trabeculotomy surgery.

      

    The authors reviewed the effects of phacoemulsification surgery in eyes with chronic hyptomy following trabeculectomy with mitomycin C.

       

    They found that statistically significant elevation in IOP occurs in association with phacoemulsification surgery in previously filtered eyes with hypotony. This may result in resolution of
    hypotony.

       

  • Rothman
    RF, Liebmann JM, Ritch R (New York Eye and Ear Infirmary; New York Med College, Valhalla)

    Low-Dose 5-Fluorouracil Trabeculectomy As Initial Surgery in Uncomplicated Glaucoma: Long-term Follow-up.

    Ophthalmology 107: 1184-1190, 2000

       

    Adjunctive antifibrosis therapy with 5-fluorouracil and Mytomycin C during or after filtering surgery has improved chances of surgical success in the treatment of primary and complicated glaucoma.

        

    The authors compared the effectiveness of trabeculectomy with adjunctive, low-dose, subconjunctival 5-fluorouracil, with trabeculectomy alone in patients undergoing their first operative procedure. They concluded that the use of adjunctive, low-dose 5-fluorouracil at initial surgery in uncomplicated glaucoma results in improved long-term IOP control and a reduction in the need for postoperative therapy. The risk of bleb related ocular infection is increased in eyes receiving 5-fluorouracil.

       

  • Tian B, Geiger B, Epstein DL, et al (Univ of Wisconsin, Madison; Weizmann Inst of Sciences, Rehovot, Israel; Duke Univ, Durham, NC)

    Cytoskeletal Involvement in the Regulation of Aqueous Humor Ouflow.

    Invest Ophthalmol Vis Sci 41: 619-623, 2000.

        

    Fluid flow in the anterior chamber supplies oxygen and nutrients to the nonvascularized cornea, lens and the trabecular meshwork.

      

    Potential long-term therapeutic benefits for lowering intraocular pressure (IOP) are offered by compounds with cytoskeletal effects.

       

    The usual IOP reducing agents either suppress production of aqueous humor or increase outflow through ciliary muscle, consequently reducing aqueous flow through a compromised trabecular meshwork and posing a threat to the cornea and lens.

          

    Recent studies reveal that the cytoskeleton of the trabecular meshwork {TM} may be involved in regulation of aqueous humor outflow.

           

    A cytoskeletal agent acting directly on the TM/Schlemm’s canal to reduce outflow resistance may be more consistent with normal physiologic function.

          

    Arrays of collagen beams covered by endothelium like cells form the TM.

        

    The cytoskeleton consists of a complex system of cytoplasmic fibers which form a number of cellular processes.

        

    The different filament networks are microfilaments, microtubules and intermediate filaments. Cytochalasins disrupt the actin cytoskeleton

        

    Ethacrynic acid works by inhibiting microtubule assembly IN VITRO.

         

    H-7 inhibits actino-myosin-driven contractility and induces general cellular relaxation.

        

    Lantruculins alter cell shape and disrupt microfilament organization. Staurosporine chelerythrine, ML-7, and the protein kinase C-activator phorbol ester have been shown to decrease outflow resistance in monkeys.

        

    Further research on the biomolecular differences between the cornea and TM may facilitate the development of TM – selective drugs that could reduce outflow resistance without affecting other eye tissues.

                                                                 

  • Christine Buckley, PWF Hadoke et al (Mater Misericordiae Hosp, Dublin, Ireland)

    Systemic Vascular Endothelial cell dysfunction in normal pressure glaucoma

    BJO. 2002, 86: 227-232

                          

    Vascular risk factors, particularly vasospasm are believed to play a role in the pathogenesis of normal pressure glaucoma (NPG).

                        

    This study identified dysfunction of the systemic vascular endothelial cell in patients with NPG. The vascular endothelium modulates contractile responses to 5-HT and ET-1 in human subcutaneous resistance arteries.

                          

    This effect is lost in patients with NPG, indicating a selective defect in agonist mediated release of endothelium derived vasodilators. 

                                     

    Selective antagonists of 5-HT and ET-1 may hence help to prevent vasospasm in patients with
    NPG.        

                                                                                                                            

  • V A Parker, J Herrtage, NJC Sarkies (Dept. of Ophth, Addenbrooke’s Hosp.Trust, Cambridge, UK)

    Clinical comparison of the Keeler Pulsair 3000 with Goldmann applanation tonometry.

    BJO, Nov.2001: 85(11): 1303-1304.

                                

    A masked study was carried out on 150 eyes by two experienced tonometrists, who compared the mean of the Goldmann intraocular pressure (IOP) readings against the pulsair 3000 reading (average of four puffs).

                                                   

    It was found that the Pulsair 3000 provides an accurate and objective method of IOP measurements and is as accurate as Goldmann
    tonometry.

       

  • H.A. Quigley, N.G. Congdon, D.S. Friedman, (Wilmer Ophth. Inst. Johns Hopkins Univ. Shool of Medicine, Baltimore, USA).

    Glaucoma in China (and worldwide): changes in established thinking will decrease preventable blindness.

    BJO, 2001; 85; 1271-1273

      

    The authors emphasise some basic fundamental concepts, stressing that we should avoid treatment of those who would NEVER have lost vision in their lives, and who may be more threatened by treatment than by the natural course of the disease.

      

    People derived from north China, including native peoples of North America and Greenland, have a high prevalence of angle closure glaucoma
    (ACG).

       

    Contrary to previous teaching, two surveys suggest that prevalence of ACG is similar among some African and Hispanic populations as among Europeans i.e. About 1/5th the rate of open angle glaucoma (OAG) in these population.

      

    ACG deserves greater emphasis as it comprises a higher proportion of all those with glaucoma. ACG blinds many more people than OAG and may be more easily treated.

     

    Although the estimated numbers of those with ACG in China are only 30% higher than those with OAG, ACG blinds 10 times more people than DAG in absolute terms.

     

    Identifying narrow angles is not enough, as the proportion of those with occludable angles is nearly 10 times the proportion of those with damage to their optic nerve from glaucoma.

      

    Simple measures of anatomical size (chamber, axial length, etc.) have failed to differentiate effectively those who will get
    ACG.

     

    Though iridotomy is the present standard approach for the initial treatment of ACG, it is subject to abuse if too many eyes are treated which would never develop the disease.

      

    Research should identify how frequently iridotomy eliminates further need for treatment.

     

    The work of Foster and Johnson shows that only 20-25% of those with ACG develop acute attacks while the remainder continue to have a chronic asymptomatic disorder. ACG of the more chronic form and OAG are both identifiable by a similar diagnostic approach viz evaluation of the optic nerve and/or visual field.

      

  • N G Congdon, P J Foster, et al (Wilmer, Baltimore, USA)

    Biometric Gonioscopy and the Effects of Age, Race, and Sex on the Anterior Chamber Angle

    BJO, January 2002; 86(1); 18-22

      

    The authors describe a novel method for making measurements in the anterior chamber to compare the anterior chamber angles of people of European, African, and east Asian descent aged 40 years and over.

     

    In this study, 15 people of each sex were chosen from each decade from the 40s to the 70s from each of 3 racial groups – black, white, and Chinese Singaporeans. Biometric gomioscopy (BG) utilising a slit lamp mounted graticule was used to make measurements from the apparent iris insertion to Schwalbe’s line through a Goldmann one mirror
    goniolens.

     

    There was no significant difference in angle measurements between black, white and Chinese. At younger ages, Chinese appeared to have deeper angles than white or black people. The angles of older Chinese were significantly narrower.

     

    The apparently more rapid decline in angle width measurements with age among Chinese may be due to the higher prevalence of cataract or “creeping angle closure”.

      



 

   

Speciality Spotlight

 

 

Glaucoma
   

  • K Strenn, B Matulla, M Wolzt, et al (Univ of Vienna)
    Reversal of Endothelin-1-induced Ocular Hemodynamic Effects by Low-dose Nifedipine in Humans.
    Clin Pharmacol Ther 63:54-63, 1998
      
    Calcium channel blockers may be beneficial in patients with normal-tension glaucoma and vasospastic reactions. Calcium channel blockers (CCB) may increase ocular-blood flow and have a functional antagonism with endothelin-1 (ET-1) in the ocular vasculature.
      
    Nifedipine reverses ET-1 induced constriction in ocular vasculature at doses that do not affect systemic hemodynamics. This suggests some association between the therapeutic effect of CCBs and the endothelin system in patients with normal tension glaucoma.
      
    The above findings provide a rationale for studying low-dose nifedipine as a supplementary medication in patients with glaucoma.
        

  • S Beatty, PA Good, J McLaughlin, et al (Birmingham and Midland Eye Centre, Birmingham, England).
    Echographic Measurements of the Retrobulbar Optic Nerve in Normal and Glaucomatous Eye.
    Br J Ophthalmol 82:43-47, 1998.
      
    The authors used a new-generation B scanner to measure orbital optic nerve dimension in eyes with glaucoma and ocular hypertension.
      
    49 patients with glaucoma and 90 controls were studied. Five repeated echographic measures of the maximal interpial diameter and cross-sectional area of the orbital optic nerve were obtained in 1 eye of each participant on two occasions.
      
    Eyes with glaucoma were found to have reduced optic-nerve interpial diameter and cross-sectional areas, indicating nerve-fibre loss. This method would be of special value in differentiating normal from glaucomatous eyes when optic-disc morphometry is not possible because of opaque media.
      

  • WL Membrey, DP Poinoosawmy, C Bunce, F W Fitzke, R A Hitchings (Moorfields Eye Hosp, London)
    Comparison of visual field progression in patients with normal pressure glaucoma between eyes with and without visual field loss that threatens fixation.
    BJO 2000; 84: 1154-1158.
      
    A large number of eyes (over 60%) without prior field loss, fail to demonstrate progressive visual field damage over a long follow up period. It is recommended that normal pressure glaucoma patients be monitored for progression and that potentially harmful therapy be withheld until progression is demonstrated.
      
    The presence of visual field loss that threatens fixation, does not necessarily constitute an increased risk of field progression. However, it does indicate an increased risk of further field loss close to fixation resulting in loss of central acuity.
      
    Hence, patients with visual field loss that threatens fixation need to be managed more aggressively.
      

  • Changwon Kee, Seong-Heon Moon. (Dept. of Ophthalmology, Samsung Medical Center College of Medicine, Seoul).
    Effect of cataract extraction and posterior chamber lens implantation on outflow facility and its response to pilocarpine in Korean subjects.
    Br.J Ophthalmol, 2000: 84: 987-989.
       
    Intraocular pressure was measured by Goldmann applanation tonometer in 42 patients with cataracts and outflow facility was measured by tonography preoperatively, before and after pilocarpine installation.
      
    All patients were operated by the same surgeon using clear corneal phaco-emulsification and a silicone foldable I.O.L. implantation within the bag.
      
    Two months after surgery, slit lamp examination, gonioscopy were performed and IOP and outflow facility were estimated.
      
    The statistical analysis carried out by the authors reveal that lens extraction causes a reduction in IOP and an increase in outflow facility in Korean subjects.
      
    Pilocarpine causes an increase in outflow facility which persists after cataract extraction and posterior chamber lens implant.
      

  • M la Cour, J F Kiilgaard, T Eysteinsson, et al (Univ of Copenhagen, Denmark; Univ of Iceland, Reykjavik, Iceland)
    Optic Nerve Oxygen Tension: Effects of Intraocular Pressure and Dorzolamide.
    Br.J. Ophthalmol 2000; 84:1045-1049
      
    The aim of this experimental exercise was to evaluate the influence of acute changes in intraocular pressure (IOP) in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500mg of dorzolamide (carbonic anhydrase inhibitor).
      
    In domestic pigs, oxygen tension was measured by means of a polarographic electrode in the vitreous 0.5mm anterior to the optic disc. This entity is called the optic nerve oxygen tension.
      
    It was found that intravenous administration of 500mg dorzolamide increases the oxygen tension at the optic nerve head during acute increases in I.O.P
      

  • D Siriwardena, A Kotecha, D Minassian, et al (Institute of Ophthalmology, London)
    Anterior chamber flare after trabeculectomy and after phacoemulsification.
    Br. J.Ophthalmol 2000; 84: 1056-1057.
       
    This study of 131 consecutive patients was undertaken to evaluate and compare prospectively anterior chamber (a.c.) flare after phacoemulsification cataract extraction and after trabeculectomy with peripheral iridectomy.
      
    None of the patients had a history of pseudoexfoliation, uveitis or previous ocular surgery. It was found that a.c. inflammation and breakdown of the blood-aqueous barrier was much more prolonged after uncomplicated small incision cataract surgery than after glaucoma filtration surgery with peripheral iridectomy.
      
    This prolonged low grade inflammation is likely to be due to release of lens crystallins and lens epithelial cells into the aqueous humour, the effect of ultrasound, and/or the high volume of fluid passing through the eye at the time of surgery. 
      
    The above factors may increase the production of fibrogenic cytokines in the aqueous humour of patients who undergo phacoemulsification. 
      
    This may explain why the success rate of phaco-trabeculectomy is significantly lower than trabeculectomy alone. It may also explain why recent cataract surgery is a risk factor for failure of filtration surgery.
      

  • Oliver Arend, Andreas Remky, et al (Department of Ophthalmology, Germany, Department of Ophthalmology, Indiana University School of Medicine, USA)
    Altitudinal visual field asymmetry is coupled with altered retinal circulation in patients with normal pressure glaucoma.
    Br.J.Ophthalmol 2000; 84: 1008-1012
       
    Particularly in normal pressure glaucoma (NPG) disturbances of ocular circulation seem important in the pathogenesis of glaucomatous neuropathy.
      
    This prospective cross section study compared patients with NPG and altitudinal ASYMMETRIC perimetric findings between the superior and inferior hemisphere (group 1), 20 NPG patients with SYMMETRICAL field defects (group 2), and 18 healthy subjects.
      
    Fluorescein angiograms were done using a scanning laser ophthalmoscope. Using digital image analysis, arteriovenous passage time (AVP) and vessel diameters were assessed for comparison of corresponding affected and less arterial arcades.
      
    It was found that both affected and less affected hemispheres showed significantly prolonged AVP times when compared with healthy subject data.
      
    In hemispheres with more severe glaucomatous field loss, the AVP times were significantly prolonged, compared with the less affected hemisphere.
      
    The authors conclude that altitudinal visual field deficits are linked together with circulatory deficits of retinal tissue.
      
    The attentuated circulation seems to be a considerable factor in the natural course of glaucomatous optic neuropathy.
      

  • Rainer G, Menapace R, Schmetterer K, et al (Univ of Vienna)
    Effect of Dorzolamide and Latanoprost on Intraocular Pressure After Small Incision Cataract Surgery.
    J Cataract Refract Surg 25: 1624-1629, 1999.
      
    If there is elevated intraocular pressure (IOP) within 24 hrs. of cataract surgery, there may be a risk of developing corneal epithelial oedema, pain, retinal artery occlusion or anterior ischaemic optic neuropathy.
       
    In a study of 102 patients, it was found that both dorzolamide and latanoprost effectively reduced IOP rises after 6 hours. However only dorzolamide was of help after 20 to 24 hours.
      
    If untreated IOP rose about 5mmHg in 6 hrs and 1.5mm Hg within 24 hours. Using dorzolamide reduced the increase of IOP significantly. Latanoprost worked well only in the shorter term. Neither dorzolamide nor latanoprost could prevent IOP spikes of 30mm Hg or above.
          

  • Thoe Schwartzenberg GWS, Trope GE (Univ of Toronto)
    Anorexia, Depression and Dementia induced by Dorzolamide Eyedrops (Trusopt)
    Can J Ophthalmol 34: 93-94, 1999
       
    This is a case report of a patient with systemic adverse effects of topical dorzolamide.
       
    The case report highlights the importance of the awareness of side effects of all topical medications used for glaucoma.
        

  • N Naveh, A Kaplan-Messas, et al (Tel-Aviv Univ.School of Medicine, Sheba Medical Centre, Israel, and St.Thomas’s Hospital, London, UK)
    Mechanism related to reduction of intraocular pressure by melanocortins in rabbits.
    Br J Ophthalmol, 2000; 84: 1411-1414
       
    A single application of melanocyte stimulating hormone (MSH), caused a sustained dose related ocular hypotensive effect without any side effects.
       
    An increase in eicosanoid and cyclic AMP (cAMP) levels following exposure of iris, ciliary body (ICB) to MSH indicates their significance in MSH induced ocular hypotension.
       
    MSH and its analogues may have clinical relevance as antiglaucoma drugs with fewer side effects because of their antiallergic and anti-inflammatory properties.
       

  • G Rainer, Rupert Menapace, Oliver Findl, et al (Univ. of Vienna, Austria)
    Intraocular pressure rise after small incision cataract surgery: a randomised intraindividual comparison of two dispersive viscoelastic agents.
    Br.J. Ophthalmol. Feb.2001, 85: 139-142.
      
    This study (prospective and randomized) comprised 80 eyes of 40 consecutive patients who had bilateral small incision cataract surgery. Phacoemulsification was done after a 3.2mm sutureless incision and a foldable silicone intraocular lens was inserted.
      
    The patients were randomly assigned to receive OCUCOAT (hydroxy-propyl methylcellulose 2%) or viscoat (sodium chondroitin sulphate 4% – sodium hyaluronate 3%) for the first eye operation. The second eye which was operated later received the other viscoelastic agent.
       
    It was found that VISCOAT causes a significantly higher intraocular pressure (IOP) increase and significantly more IOP spikes thank OCUCOAT in the early postoperative period.
       

  • T Manners, J F Salmon, A Barron, et al (Groote Schuur Hospital, Cape Town, South Africa)
    Trabeculectomy with mitomycin C in the treatment of post-traumatic angle recession glaucoma.
    Br J Opthahlmol, Feb.2001, 85: 159-163.
       
    Traumatic angle recession is a risk factor for failure of glaucoma filtration surgery. This study is a retrospective analysis of 43 consecutive trabeculectomy procedures in 41 patients followed for a mean period of 25 months.
       
    Mitomycin C 0.02% was applied between the sclera and conjunctiva for one to five minutes at the time of surgery.
       
    The authors found trabeculectomy with mitomycin C application, an effective surgical procedure. There was good intraocular pressure control and most cases had good preservative of vision.
       

  • A Sciscio, Anthony G Casswell, (Sussex Eye Hospital, Brighton, UK)
    Effectiveness of apraclonidine 1% in preventing intraocular pressure rise following macular hole surgery.
    Br. J Ophthalmol. Feb.2001, 85 : 164-168.
       
    Twenty-six eyes (of 25 patients) were studied in a prospective, double masked, randomised study, to compare apraclonidine hydrochloride 1%, an A2 agonist (12 eyes) with a placebo (14 eyes) in the prevention of intraocular pressure (IOP) spikes following macular hole surgery.
      
    Macular hole repair surgery was performed with a vitrectomy, platelet adjunct, and complete fill of the vitreous cavity with perfluoropropane gas (C3F8) at a concentration of 16%.
       
    It was found that apraclonidine hydrochloride 1% was efficacious and safe in the prophylaxis of early IOP spikes in patients undergoing macular hole surgery.
       

  • O.J. Lehmann, C. Bunce et at [Moorfields Eye Hospital, London, UK]
    Risk Factors for Development of post-trabeculectomy endophthalmitis.
    BJO 2000; 84: 1349-1353
       
    This article describes a case-control study performed on patient with post trabeculectomy endophthalmitis over a period of 6.5 years.
       
    The results provide strong evidence of an increased risk of late endophthalmitis in patient who have diabetes mellitus, patients with blebitis. Antiproliferative agents may also have a significant role towards increasing the risk.
        

  • Ahmed M Abu, EI-Asrar, Sofie Struyf et al [King Saud Univ, Riyadh, Saudhi Arabia]
    Chemokines in the Limbal Form of Vernal Ketatoconjunctivitis 
    BJO 2000; 84: 1360-1366
       
    Chemokines are a family of low molecular weight cytokines that attract and activate leucocytes. The CC chemokines play an important part in allergic diseases.
        
    The aim of the study was to investigate the expression of CC chemokines, in the conjunctiva of patients with vernal keratoconjunctivities.
       
    The results demonstrated a definite increase in the expression of chemokines in the conjuctiva of patients with vernal keratoconjunctivities [VKC] suggesting a potential role for chemokines in the pathogenesis of VKC.
       
    Antagonists of chemokine receptors may provide new therapeutic modalities in VKC.
        

  • KRG Martin, DC Broadway (West Norwich Hosp. UK)
    Cyclodiode Laser Therapy for Painful Blind Glaucomatous Eyes
    Br.J Ophth 2001: 85; 474-476

    Cyclodiode laser treatment was found to be very effective in eliminating discomfort in painful, blind glaucomatous eyes.

    The best predictor of successful pain relief was intraocular pressure reduction more than 30% from the base line.

    Protocols using slightly less total energy delivery to the ciliary body might have a lower risk of hypotony but in such cases retreatment may be required.
       

  • W Birchall, V Kumar (Royal Eye Hosp., Manchester and Stepping Hill Hospital, Stockport UK)
    A Comparative study of proxymetacaine – fluorescein and lignocaine – fluorescein use during applanation tonometry
    Br J Ophthal 2001; 85, 477-479

    This article analyzed the results of a randomized masked, double-blind prospective study of 60 consecutive patients, assessing the duration of the stinging sensation, degree of discomfort, the extent of reflex lacrimation, the need for subsequent tear film manipulation, and total time to complete tonometry.

    Proxymetacaine fluorescein (PROX- FLU) caused significantly less discomfort and reflex lacrimation than lignocaine fluorescein (LIG-FLU). Accurate tonometry was more rapidly completed when PROX-FLU was used. PROX-FLU was preferred by 98% of study patients.
       

  • K. Miyake, I Ota et al (Chiba Hokuso Hospital, Nippon Medical School, Chiba; and Kushimoto Rehabilitation Center Wakayama, Japan)
    Enhanced Disruption of the Blood-Aqueous Barrier and the Incidence of Angiographic Cystoid Macular Edema by topical Timolol and its preservative in Early Postoperative Pseudophakia
    Arch.of Ophth. Vol.119, March 2001, p.387-394.

    Timolol and its preservative, benzalkonium chloride, cause disruption of the blood aqueous barrier in early postoperative pseudophakia, along with increased incidence of angiographic cystoid macular edema (CME).

    The concurrent administration of diclofenac prevents these adverse effects without any effect on the fall in intraocular pressure.

    The presence of benzalkonium chloride contributes considerably to these adverse effects of timolol.
      

  • P.R. Egbert, S. Fiadoyor et al (Stanford Univ. Ca; Cape Coast Ghana; Bascom Palner Eye Inst. Miami, Fla)
    Diode Laser Transcleral Cyclophotocoagulation as a Primary Surgical Treatment for Primary Open-angle Glaucoma.
    Arch.Ophthal, Vol.119, March 2001, p.345-350.
       
    This study was undertaken in 92 patients, to evaluate the feasibility of diode laser transcleral cyclophotocoagulation (TSCPC) as a primary treatment for open-angle glaucoma and to compare two laser energy settings.

    It was found that diode laser TSCPC is a practical rapid well-tolerated procedure providing a modest but variable lowering of intraocular pressure. The only complication in some cases was an atonic pupil. Moderate variation in laser energy settings does not influence the results.
       

  • RE Warwar, JD Bullock, D Ballal (Wright State Univ, Dayton, Ohio) 
    Cystoid Macular Edema and Anterior Uveitis Associated with Latanoprost Use: Experience and Incidence in a Retrospective Review of 94 patients. 
    Ophthalmology 105: 263-268, 1998.
       
    Latanoprost, a prostaglandin analogue, is the first of a new class of drugs developed to reduce intraocular pressure.
       
    Out of 94 patients and a total of 163 eyes reviewed anterior uveitis developed in 6.4% of the patients and in 4.9% of all eyes during latanoprost treatment. CME occurred in 2.1% of patients and in 1.2% of all eyes.
      
    Clinicians need to be aware of these possible complications when using latanoprost.
       

  • O Cekic, C Batman (SSK Ankara Eye Hosp, Turkey)
    Effect of Capsulorrhexis Size on Postoperative intraocular pressure.
    J Cataract Refract Surg 25: 416-419, 1999
       
    The possible effect of capsulorrhexis size on intraocular pressure (IOP) was prospectively examined in 58 eyes of patients undergoing clear corneal phacoemulsification with IOL implantation.
      
    It was found that a 4mm capsulorrhexis produced a lower postoperative IOP compared with a 6mm capsulorrhexis.
      
    Editorial comments on the above article:
        
    Though a large capsulorrhexis makes it easier to mobilize the nucleus and to place the IOL within the capsular bag, there are several disadvantages of this large capsulorrhexis.
    (1) IOL fixation is not stable (2) Greater chances of iridocapsular synechia (3) Unwanted optical images from edge glare effect because of the overlying of the capsulorrhexis on the lens optic.
       
    The authors speculate on several reasons as to why a smaller capsulorrhexis may produce a lower postoperative IOP, than a larger capsulorrhexis. In patients with anterior capsule contraction syndrome, it is often observed that they have a low IOP and after YAG laser capsulotomy the IOP will rise.
        

  • Hedner J, Everts B, Strom Moller C (Sahlgrenska Univ, Goteborg, Sweden; Pharmacia & Upjohn, Stockholm)
    Latanoprost and Respiratory Function in Asthmatic Patients Randomized Double-Masked, Placebo-controlled Crossover Evaluation.
    Arch Ophthalmol 117: 1305-1309, 1999
      
    ß-receptor antagonist agents used to treat glaucoma may adversely affect the patient’s respiratory disorder. The possible effect of latanoprost, on respiratory function, especially of patients with asthma who have not previously taken corticosteroids, was investigated.
      
    Latanoprost treatment produced no alterations in resting or provoked airway function, or in asthma symptoms, in this group of patients who had not used corticosteroids previously.
        

  • Rasheed ES (El Maghraby Eye Ctr, Madina)
    Initial Trabeculectomy with Intraoperative Mitomycin-C Application in Primary Glaucomas
    Ophthalmic Surg Lasers 30: 360-366, 1999.
      
    Mitomycin C is an alkylating agent acting at all stages of the cell cycle. It reportedly inhibits fibroblast proliferation by preventing DNA synthesis, thereby decreasing the amount of scar tissue formation after trabeculectomy.
      
    The authors conducted a randomized study which compared the overall efficacy of the intraoperative application of Mitomycin C. They found that the use of intraoperative Mitomycin C may increase the success rate of glaucoma surgery. They felt that close follow-up and meticulous patient management are required, especially in the early post-operative period.
      
    Complications described are those that occur immediately postoperatively, related primarily to excessive filtration. Eyes with an overfiltering or leaking bleb are often uncomfortable to the patient. Vision is blurred due to low pressure and the excessive moisture on the corneal surface and the patient may suffer from photophobia.
      
    The late complications can be endophthalmitis, blebitis and hyptomy.
       

  • A Raihan, Sekhat GC, Naduvilath TJ, et al (LV Prasad Eye Inst, Hyderabad, India)
    The Role of Tenonectomy in Trabeculectomy
    Indian J Ophthalmol 47: 117-119, 1999
      
    The effects of tenonectomy in reducing IOP during trabeculectomy were retrospectively reviewed.
      
    Tenonectomy appears to reduce not only mean IOP but also increases the percentage of patients reaching a target IOP of 14mm Hg.
      
    Editorial comments on the above article:
    The editor rarely does a tenonectomy and does not plan to start doing it routinely.
      
    The purposes of glaucoma surgery are :
    (1) To lower IOP
    (2) To prevent visual field loss
    (3) To protect the optic nerve from glaucoma damage
    (4) To enhance the health of the patient
    (5) To relieve pain
    (6) To develop a filtering bleb.
      
    It is not known whether it is the AMOUNT of pressure-lowering or the STABILITY of pressure-lowering that is the critical aspect. If the pressure is lowered precipitously, surgery is more likely to be associated with a super choroidal expulsive haemorrhage. Pressure lower than 10mm Hg may lead to deterioration of vision caused by unstable refractive error, or in rarer cases, choroidal folds in the macular oedema. 
      
    The younger, the more myopic and the less damaged the optic nerve, the more likely is the low pressure to be associated with macular oedema.
      
    There is evidence that an IOP below 10mm Hg predisposes to retinal vein occlusion or even to more rapid progression of field loss.
      
    The health of the patient is enhanced by preventing visual field loss and avoiding the side effects of treatment.
      
    Tenonectomy may be appropriate to perform in selected cases when a low IOP is desired and the problem of a thin filtering bleb is of not much concern.
      

  • Jacobi PC, Dietlein TS, Krieglstein Gk (Univ Eye Hosp Cologne, Germany)
    Goniocurettage for Removing Trabecular Meshwork: Clinical Results of a New Surgical Technique in Advanced Chronic Open-Angle Glaucoma.
    Am J Ophthalmol 127: 505-510, 1999
      
    Goniocurettage may deal more directly with the area of resistance to aqueous outflow. The procedure is carried out with an instrument resembling a microchalazion curette. The curettage removes trabecular tissue from the angle.
      
    The authors evaluated the procedure in 25 eyes of patients who had had unsuccessful filtering procedures for chronic open angle glaucoma and found that goniocurettage controlled intraocular pressure over a lengthy period of time. Patients who have excessive conjunctival scarring may benefit from this procedure.
      

  • Kosmin AS, Wishart PK (Royal Liverpool Univ, England)
    A Full-Thickness Scleral Graft for the Surgical Management of a Late Filtration Bleb Leak.
    Ophthalmic Surg Lasers 28: 461-468, 1997.
      
    Late bleb leak can occur months to years after filtration surgery. Eight leaking blebs were repaired, using a full thickness scleral graft. This procedure was effective, particularly for leaks associated with full thickness scleral defects. Inspite of IOP spikes occurring early in the postoperative period, long-term IOP control was usually achieved with no need for further filtration surgery.
       

  • Trible JR, Schultz RO, Robinson JC, et al (Med College of Wisconsin, Milwaukee)
    Accuracy of Scanning Laser Polarimetry in the Diagnosis of Glaucoma
    Arch Ophthalmol : 117: 1298-1304, 1999
      
    Improved methods of screening for glaucoma could decrease the degree of damage caused by the disease.
      
    Patients with glaucomatous damage can be differentiated from those with normal findings using scanning laser polarimetry, but many cases with severe damage were missed with this method.
      

  • Salgarello T, Colotto A, Falsini B, et al (Catholic Univ, Rome)
    Correlation of Pattern Electroretinogram with Optic Disc Cup Shape in Ocular Hypertension.
    Invest Ophthalmol Vis Sci 40: 1989-1997, 1999
      
    The pattern electroretinogram (PERG) provides an index of inner retinal function. The correlation of PERG findings and confocal scanning laser ophthalmoscopy in ocular hypertension (OHT) was investigated.
      
    It was found, (in a study of 34 patients with OHT) that the shape of the optic disc cup, is significantly, though weakly, correlated with PERG amplitude. Hence the authors postulate that combined PERG and optic disc cup structural analysis (with confocal scanning laser ophthalmoscopy) may be of diagnostic value for detecting early damage to the optic nerve head in patients with OHT.
       
    Editorial comments on the above article:
    Standard electroretinography with a flash that illuminates most of the fundus, picks up glaucoma damage, only when it is advanced.
      
    The PERG, which is able to isolate localized areas of the retina more specifically, is theoretically more likely to detect early glaucoma defects.
      
    However, there is no convincing evidence to date that those patients in whom PERG noted a defect, are patients who WILL have progressive glaucomatous nerve damage. Nor is there any evidence that those in whom PERG results are normal will NOT have glaucomatous damage in future.
      
    Multifocal electroretinogram (ME) which stimulated a more localized area of the retina may be more accurate than PERG, but studies with ME are even more preliminary.
       

  • Shareef S, Sawada A, Neufeld AH (Washington Univ, St. Louis)
    Isoforms of Nitric Oxide Synthase in the Optic Nerves of Rat Eyes with Chronic Moderately Elevated Introcular Pressure.
    Invest Ophthalmol Vis Sci 40: 2884-2891, 1999.
      
    Nitric oxide synthase (NOS) contributes to the formation of Nitric Oxide (NO) from L-arginine. Rat CNS demonstrates 3 NOS isoforms, but rat eyes are devoid of NOS.
      
    The isoforms NOS-1 and NOS-3 are found in NORMAL human optic nerve heads. All 3 isoforms have been noted in the optic nerve head of patients with primary open-angle glaucoma.
      
    After cautery of 3 episcleral vessels, unilateral raised intraocular pressure (IOP) was produced in rats.
      
    Rat eyes that had elevated IOP because of cautery, had no detectable changes in NOS-1 and NOS-3, but NOS-2 was noted in the astrocytes of the optic nerve heads and remained for upto 3 months.
      
    The authors concluded that when there is chronic moderately elevated IOP, NOS-2 appears in astrocytes and may contribute to the neurotoxicity of retinal ganglion cells.
       
    These findings may have implications for the choice of pharmacologic agents used to treat glaucoma.
        

  • JH Gurwitz, SM Yeomans, RJ Glynn, et al (Meyers Primary Care Inst, Worcester, Mass; Univ of Mass, Worcester; Harvard Med School, Boston)
    Patient Noncompliance in the Managed Care Setting: The Case of Medical Therapy for Glaucoma
    Med Care 36: 357-369, 1998.
        
    Accurately identifying which patients are most likely to be noncompliant is still a challenging task. Demographic and clinical characteristics associated with noncompliance in patients beginning medical treatment for glaucoma in a managed care setting were studied retrospectively.
        
    Out of 616 patients, 152 (24.7%) met the criteria for noncompliance. During the one year study, the mean number of days without treatment was 103.9, compared with 6.8 for those categorized as compliant. 
    The variable most strongly associated with non-compliance was fewer visits to an ophthalmologist. Identifying who would likely to be noncompliant using demographic and clinical data remains difficult.
        

  • PJ Foster, J Baasanhu, PH Alsbirk, et al (Inst of Ophth. London; Med. Univ, Ulaanbaator Mongolia; Hillerod Hosp, Denmark)
    Central Corneal Thickness and Intraocular Pressure in a Mongolian Population.
    Ophthalmology 105: 969-973, 1998.
        
    Differences in central corneal thickness (CCT) have been shown to affect tonometric estimates of IOP. Correlation between IOP measurements and CCT was studied in 1244 residents of a Mongolian town.
        
    The collected data suggested that variations in CCT account for changes in IOP estimates. When the additional effect of age on CCT is considered, even more variation in IOP can be accounted for by CCT.
         

  • RS Rubinfeld, EJ Cohen, PR Laibson, et al (Wills Eye Hosp, Philadelphia)
    The Accuracy of Finger Tension for Estimating Intraocular Pressure After Penetrating Keratoplasty.
    Ophthalmic Surg Lasers 29:213-215, 1998.
        
    Goldmann tonometry, if used immediately after a penetrating keratoplasty (PK), is not an accurate estimate of intraocular pressure (IOP).
        
    The finger tension method for estimating IOP after PK can be useful. Its utility relies on proper technique and the absence of lid oedema.
        

  • YH Yucel, N Gupta, MW Kalichman et al (Univ of California, San Diego; Univ of Toronto; Allergan Inc, Irvine, Calif)
    Relationship of Optic Disc Topography to Optic Nerve Fiber Number in Glaucoma.
    Arch Ophthalmol 116:493-497, 1998.
       
    Measures of optic-disc topography were compared with the number of surviving optic-nerve fibres in glaucoma. 
       
    Ten monkeys with laser induced glaucoma in the right eye were studied. A confocal scanning laser ophthalmoscope was used to measure optic-disc topography in vivo. Histomorphometry was done on optic-nerve cross-sections, using bright-field microscopy with camera lucida.
       
    Most optic-disc topography measures were significantly associated with the number of optic-nerve fibres. The data support the use of confocal scanning laser ophthalmology to assess optic-nerve damage in glaucoma.
        

  • ST Hoh, DS Greenfield, JM Liebmann, et la (The New York Eye and Ear Infirmary; New York Med College, Valhalla; Singapore Eye Research Inst; et al ) 
    Factors Affecting Image Acquisition During Scanning Laser Polarimetry. 
    Ophthalmic Surg Lasers 29: 545-551, 1998.
        
    Scanning Laser Polarimetry (SLP) is a noninvasive technique, which enables quantitative measurement of peripapillary retinal-nerve fibre layer (RNFL) thickness. Artifacts which may be observed during RNFL measurement with SLP, were described.
        
    Four hundred and twenty six patients were reviewed.
       
    Anterior and posterior segment abnormalities, especially those localized to the cornea and lens, may cause spurious RNFL measurements.
       
    According to recent reports, there is a co-relation between the appearance of the optic nerve and nerve-fibre layer as determined by HEIDELBERG Retinal Tomography, and the number of neurons present. Hence it may be possible to get an idea of glaucoma damage by estimating nerve fibre layer thickness. However, there are differences between reproducibility and validity. It is important to realize that there are still many hazards to using image-analysis techniques.
        

  • Lill-Inger Larsson, (Uppsala Univ. Hospital, Uppsala, Sweden)
    Aqueous Humor Flow in Normal Human Eyes Treated with Brimonidine and Timolol, Alone and in Combination.
    Arch Ophthalmol, April 2001; vol.119, pg.492-495
      
    Topically applied 2% brimonidine tartrate was compared with topical 0.5% timolol maleate alone, and in combination, in a randomized, double-masked, placebo-controlled study of 20 human subjects.
       
    Brimonidine reduced aqueous humor flow by 33.1%, timolol by 49.9%, and the combination of brimonidine and timolol by 58.9%. Brimonidine reduced the IOP by 20.3%, timolol by 22.9%, and the combination by 34.7%.
       
    The results of this study indicate that brimonidine suppresses aqueous humor formation, but not as efficiently as timolol.
       
    When timolol and brimonidine were applied in combination a further reduction of aqueous humor flow and IOP was seen.
      
    Evidence supports the theory that brimonidine has some additional ocular hypotensive effect through enhancement of aqueous outflow.
       

  • R A Laibovitz, A M VanDenburgh, et al (Eye Research Associates, Austin, Texas and Allergan Inc. Ophthalmology Clinical Research, Irvine, Calif.)
    Comparison of the Ocular Hypotensive Lipid AGN 192024 with Timolol.
    Dosing, Efficacy and Safety Evaluation of a Novel Compound for Glaucoma Management.
    Arch.Ophthal, vol.119, July 2001, pp.994-1000
       
    This article analyses a 30-day, randomized investigator-masked, clinical trial involving 100 patients with raised intra-ocular pressure (IOP), to compare the safety and efficacy of the ocular hypotensive lipid AGN 192024 (Lumigan) with timolol.
       
    It was found that a dosage of 0.03% AGN 192024 once daily, lowered IOP significantly more than timolol and provided better diurnal IOP control.
       
    Twice-daily dosage of AGN 192024 was of no significant benefit over once a day usage.
        
    AGN 192024 was safe, well tolerated and provided superior ocular hypotension and diurnal IOP control, compared with timolol.
       

  • P.Demailly, C Allaire, C Trinquand, for the Once-daily Carteolol Study Group (Laboratories Chauvin, Montpellier, France)
    Ocular hypotensive efficacy and safety of once daily carteolol alginate
    B.J.O. Aug.2001; 85: 921-924

    This was a double masked, multicentre study of patients with ocular hypertension or open angle glaucoma, randomly assigned to receive either carteolol alginate four times a day or standard carteolol twice a day.

    It was found that the new alginate formulation of carteolol 2% administered once daily was as effective as standard carteolol 2% given twice a day. There were no meaningful differences regarding safety.
       

  • A Kotecha, D Siriwardena, et al (Institute of Ophthalmology and Moorfields Eye Hospital, London, UK)
    Optic disc changes following trabeculectomy: longitudinal and localization of change.
    Br. J. Ophthal, August 2001; 85: 956-961

    95 patients undergoing routine trabeculectomy (part of Moorfields/MRC 5-Fluorouracil trial) were recruited into this study.

    Eyes were imaged preoperatively with the Heidelberg retina tomograph (HRT, Heidelberg Engineering),, and at 3 months, 1 year, and 2 years after surgery.

    The predefined segment analysis available on the HRT analysis software was used to determine segmental change.

    .Intraocular pressure reduced with the passage of time. Maximum depth of cup reduced by the 3rd and 12th month.

    The authors conclude that reversal of disc cupping is present 2 years after trabeculectomy. The factor most influencing change is reduction of intraocular pressure. Segmental analysis showed that change in rim volume was maximal in the nasal, inferonasal, superonasal and superotemporal regions.
       

  • L Rojas, G Ortiz, et al (Bogota, Colombia)
    Ghost cell glaucoma related to snake poisoning 
    Arch Ophthalmol Vol. 119, August 2001 Pg. 1212-1213
       
    This is an interesting case report of a 44 year old male farmer who was examined in the emergency department of Hospital San Juan de Dios, National University of Colombia, Bogota, 72 hours after a snake bite (BOTHROPS ATHROX) in his right foot.
       
    The snakebite produced various manifestations
    1) Subconjunctival hemorrhage.
    2) Stromal and epithelial corneal edema. 
    3) Cells and flare in the anterior chamber.
    4) Vitreous hemorrhage.
    5) The intraocular pressure (IOP) was elevated in the left eye to 40 mm Hg.
    Two days after admission the patient complained of bilateral visual loss – hand movement in the right eye and light perception in the left eye. 
    6) Two weeks later, indirect ophthalmoscopy showed optic nerve pallor, and attenuated retinal vasculature.
    7) In the left eye a rhegmatogenous retinal detachment with macular involvement was seen.
        
    The authors postulate that vitreous hemorrhage leads to secondary glaucoma producing “ghost cell glaucoma” (GCG).
         
    Ghost cells (GCs) are degenerated spherical erythrocytes that partially lose their hemoglobin content by aging for a long time in the vitreous. Hemoglobin abandons the red blood cell and forms clumps that adhere to vitreous bands. Whatever hemoglobin remains in the red blood cell becomes denatured and binds to the internal surface of the cell membrane forming granules (Heinz bodies).
    Neither fresh red blood cell nor GCs can pass through an intact anterior hyaloid membrane, therefore a hyaloid injury must be present for these cells to be found in the anterior segment.
        
    Increased IOP usually occurs 2 to 4 weeks after the injury. This complication requires repeated lavage of the anterior chamber or vitrectomy to remove the hemorrhagic tissue. 
        
    GCG has been associated with diabetic vitreous hemorrhage without previous trauma or surgery as well as in other rare cases.
        
    Snake venoms especially from crotalids as in the case of BOTHROPS, contain proteolytic enzymes capable of breaking tissue proteins, thereby causing hemorrhage.
        
    Vipers venom alters vascular resistance as well as vascular integrity, alters coagulation mechanisms, and changes in the central nervous system, cardiovascular and pulmonary dynamics.
        
    Hyaluronidase, collagenase and other proteolytic enzymes present in the BOTHROPS venom may decrease the vitreous viscosity and alter the anterior hyaloid permeability which may allow migration of the GCs in the aqueous, leading to secondary glaucoma. 
         
    Ghost cells were identified by Papanicolaou stain.
        

  • Schwartz M, Yoles E (Weizmann Inst of Science, Rehovot, Israel)
    Self-Destructive and Self-Protective Processes in the Damaged Optic Nerve: Implications for Glaucoma
    Invest Ophthalmol Vis Sci 41: 349-351, 2000
      
    Degeneration in glaucoma is similar to that in any neurodegenerative disease in which disruptive forces emanating from the disease process, as a result of the primary insult, contribute to the self-propagating process of degeneration.
      
    The authors postulate that primary insult to the optic nerve awakens extra and intracellular processes, along with global immune mechanisms. Some of these processes are destructive, while others are beneficial and potentially capable of producing self-repair.
      
    One of the risk factors for glaucoma may be uncontrollable rise in the level of biochemical compounds such as glutamate and nitric acid which are triggered off by degenerating nerve. However, glutamate has an intermediate level at which it is not detrimental and, in fact, is even beneficial in triggering an intracellular mechanism of self defence.
      
    It is possible that endogenous T-cell immune response to optic nerve damage is beneficial, though limited.
      
    Accumulation of autoimmune T-cells may offer a source of neurotrophic factors, contributing to the self-repair mechanism.
        

  • Wax MB (Washington Univ, St.Louis)
    Is There a Role for the Immune System in Glaucomatous Optic Neuropathy?
    Curr Opin Ophthalmol 11: 145-150, 2000
      
    Autoimmune-mediated glaucoma injury appears to occur most often, though not solely, in patients whose intraocular pressure (IOP) has never been increased.
       
    Signal pathways of the immune system appear to regulate cell death in response to conditions that stress retinal neurons in glaucoma. Such conditions may include (i) Mechanical stress from high IOP (ii) ischemia (iii) excessive excitatory aminoacids (iv) toxic products resulting from excessive nitric acid synthase production in neurons or glial fibres surrounding the optic nerve.
        

  • Bradley JMB, Anderssohn AM, et al (Oregon Health Sciences Univ, Portland)
    Mediation of Laser Trabeculoplasty-Induced Matrix Metalloproteinase Expression by IL-1b and TNFa.
    Invest Ophthalmol Vis.Sci 41; 422-430, 2000
        
    Laser trabeculoplasty (LT) of the anterior uveal region of the trabecular meshwork results in sustained metalloproteinase expression in the juxtacanalicular area.
      
    The authors found that LT induces interleukin (IL)-1b and tumor necrosis factor (TNF)a expression and secretion during the first 8 hours after laser treatment.
       
    These cytokines, in turn, lead to increased trabecular stromelysin expression, which initiates remodeling of the juxtacanalicular extracellular matrix ( a likely site for aqueous outflow resistance), thus restoring outflow facility.
       
    However histopatologic studies have shown focal areas of superficial scarring of the trabecular meshwork. Further studies showed significant remodeling of the trabecular tissues following argon LT.
      
    Patients with increased pigmentation of the posterior trabecular meshwork are more likely to benefit from argon LT.
       
    Argon LT tends to work more effectively in elderly patients than those less than 40 yrs of age.
      
    It is imperative to use the minimum amount of energy in order to achieve beneficial effect on IOP.
            

  • Gross RL, Hensley SH, Gao F, et al (Baylor College of Medicine, Houston)
    Effects of Betaxolol on Light Responses and Membrane Conductance in Retinal Ganglion Cells.
    Invest Ophthalmol Vis Sci 41: 722-728, 2000
          
    The physiologic effects of betaxolol on retinal ganglion cells were investigated, and its potential to elicit neuroprotective response against retinal cell degeneration was determined, in an experiment where living retinal slice preparations of the larval tiger salamander were studied.
        
    The authors postulate that betaxolol prevents retinal ganglion cell death induced by increased extracellular glutamate or by increased spontaneous spike rates under pathologic conditions.
         
    Physiologic actions of betaxolol result in a decrease in neurotoxic effects in ganglion cells, which are most susceptible to glutamate-induced damage under ischemic and glaucomatous conditions.
         

  • Erickson KA, Schroeder A (Boston Univ.; New England College of Optometry, Boston).
    Direct Effects of Muscarinic Agents on the Outflow Pathways in Human Eyes
    Invest Ophthalmol Vis Sci 41: 1743-1748, 2000
           
    It was believed that muscarinic agonists bind to receptors in the ciliary muscle, causing contraction of the muscle, displacement of the scleral spur and widening of the spaces in the trabecular meshwork, facilitating aqueous humor outflow.
         
    However, recent studies have demonstrated that cells derived from human trabecular meshwork have muscarinic receptors.
          
    The authors studied whether muscarinic agonists could change outflow facility in perfused human ocular anterior segments, which did not have an intact ciliary muscle.
          
    Dissection and perfusion of human eyes was performed.
          
    Pilocarpine, aceclidine, or carbachol were added to the perfusion medium in 4 sequential concentrations. Outflow facility was measured for one hour after addition of each drug and compared with baseline measurements.
          
    The authors concluded that in human eyes, outflow facility is increased by muscarinic agonists by a direct stimulation of outflow tissues even in the absence of an intact ciliary muscle.
           
    An important observation was that outflow facility was better with LOWER concentrations, while higher concentrations had very little or no effect.
           

  • Selbach JM, Gottanka J, et al (Univ of Essen, Germany; Univ. of Erlangen-Nurnberg, Germany)
    Efferent and Afferent Innervation of Primate Trabecular Meshwork and Scleral Spur.
    Invest Ophthalmol Vis Sci 41: 2184-2191, 2000
          
    The authors investigated the correlation between nerve terminals and cells or extracellular matrix (ECM) components in different parts of the primate TM (trabecular meshwork) and scleral spur (SS).
          
    Serial sections through anterior segments of 10 monkey eyes and 12 human eyes were studied immunohistochemically.
           
    The authors found that the trabecular meshwork may have some ability to self-regulate aqueous humor outflow via cholinergic and nitrergic nerve terminals.
         

  • Karali A, Russell P, Stefani FH, et al (Univ of Erlangen-Nurnberg, Germany; NIH, Bethesda, Md; Univ of Munich, Germany)
    Localization of Myocilin/Trabecular Meshwork-Inducible Glucocorticoid Response Protein in the Human Eye.
    Invest Ophthalmol Vis Sci 41: 729-740, 2000
       
    Myocilin is also known as trabecular meshwork-inducible glucocorticoid response protein (TIGR). Distribution and cellular localization of myocilin/TIGR was evaluated in the human eye.
       
    Immunohistochemical analysis was carried out on 25 enucleated human eyes from patients with posterior choroidal melanoma as well as on 7 normal human donor eyes.
       
    Immunoreactivity for myocilin/TIGR was demonstrated in cells of the corneal epithelium and endothelial, and extracellularly in the corneal stroma and sclera.
       
    Positive staining was observed in cells of the uveal and corneo-scleral meshwork in the trabecular meshwork and area adjacent to Schlemm’s canal.
        
    Positive staining was also seen in cells of the ciliary epithelium, ciliary muscle, lens epithelium, stromal and smooth muscle cells of the iris and throughout the vitreous.
       
    The outer surface of rods and cones, neurons of both inner and outer nuclear layer, and axons of optic nerve ganglion cells also showed positive staining.
       
    The authors postulate that the presence of myocilin/TIGR in optic nerve axons as well as astrocytes of the lamina cribrosa, suggests that in GLC1A-linked open-angle glaucoma, the trabecular meshwork may not be the only target of abnormal myocilin/TIGR.
       

  • Ugurlu S, Hoffman D, Garway-Heath DF, et al (Univ of California, Los Angeles; Yale Univ, New Haven, Conn)
    Relationship Between Structural Abnormalities and Short-Wavelength Perimetric Defects in Eyes at Risk of Glaucoma
    Am J Ophthalmol 129: 592-598, 2000
        
    Detectable structural changes precede functional abnormalities detected with standard white-on-white static threshold perimetry.
       
    In this study, 72 patients at risk of glaucoma with normal white-on-white full threshold perimetry, underwent blue-yellow full threshold perimetry prospectively.
       
    In patients with ocular hypertension, clinically detectable structural abnormalities often co-exist with blue-yellow perimetric defects.
        

  • Doyle JW, Smith MF (Univ. of Florida, Gainesville)
    Effect of Phacoemulsification Surgery on Hypotony Following Trabeculectomy Surgery.
    Arch Ophthalmol 118: 763-765, 2000
       
    Chronic hypotomy is a frustrating complication following the use of local antimetabolites in trabeculotomy surgery.
      
    The authors reviewed the effects of phacoemulsification surgery in eyes with chronic hyptomy following trabeculectomy with mitomycin C.
       
    They found that statistically significant elevation in IOP occurs in association with phacoemulsification surgery in previously filtered eyes with hypotony. This may result in resolution of hypotony.
       

  • Rothman RF, Liebmann JM, Ritch R (New York Eye and Ear Infirmary; New York Med College, Valhalla)
    Low-Dose 5-Fluorouracil Trabeculectomy As Initial Surgery in Uncomplicated Glaucoma: Long-term Follow-up.
    Ophthalmology 107: 1184-1190, 2000
       
    Adjunctive antifibrosis therapy with 5-fluorouracil and Mytomycin C during or after filtering surgery has improved chances of surgical success in the treatment of primary and complicated glaucoma.
        
    The authors compared the effectiveness of trabeculectomy with adjunctive, low-dose, subconjunctival 5-fluorouracil, with trabeculectomy alone in patients undergoing their first operative procedure. They concluded that the use of adjunctive, low-dose 5-fluorouracil at initial surgery in uncomplicated glaucoma results in improved long-term IOP control and a reduction in the need for postoperative therapy. The risk of bleb related ocular infection is increased in eyes receiving 5-fluorouracil.
       

  • Tian B, Geiger B, Epstein DL, et al (Univ of Wisconsin, Madison; Weizmann Inst of Sciences, Rehovot, Israel; Duke Univ, Durham, NC)
    Cytoskeletal Involvement in the Regulation of Aqueous Humor Ouflow.
    Invest Ophthalmol Vis Sci 41: 619-623, 2000.
        
    Fluid flow in the anterior chamber supplies oxygen and nutrients to the nonvascularized cornea, lens and the trabecular meshwork.
      
    Potential long-term therapeutic benefits for lowering intraocular pressure (IOP) are offered by compounds with cytoskeletal effects.
       
    The usual IOP reducing agents either suppress production of aqueous humor or increase outflow through ciliary muscle, consequently reducing aqueous flow through a compromised trabecular meshwork and posing a threat to the cornea and lens.
          
    Recent studies reveal that the cytoskeleton of the trabecular meshwork {TM} may be involved in regulation of aqueous humor outflow.
           
    A cytoskeletal agent acting directly on the TM/Schlemm’s canal to reduce outflow resistance may be more consistent with normal physiologic function.
          
    Arrays of collagen beams covered by endothelium like cells form the TM.
        
    The cytoskeleton consists of a complex system of cytoplasmic fibers which form a number of cellular processes.
        
    The different filament networks are microfilaments, microtubules and intermediate filaments. Cytochalasins disrupt the actin cytoskeleton
        
    Ethacrynic acid works by inhibiting microtubule assembly IN VITRO.
         
    H-7 inhibits actino-myosin-driven contractility and induces general cellular relaxation.
        
    Lantruculins alter cell shape and disrupt microfilament organization. Staurosporine chelerythrine, ML-7, and the protein kinase C-activator phorbol ester have been shown to decrease outflow resistance in monkeys.
        
    Further research on the biomolecular differences between the cornea and TM may facilitate the development of TM – selective drugs that could reduce outflow resistance without affecting other eye tissues.
                                                                 

  • Christine Buckley, PWF Hadoke et al (Mater Misericordiae Hosp, Dublin, Ireland)
    Systemic Vascular Endothelial cell dysfunction in normal pressure glaucoma
    BJO. 2002, 86: 227-232
                          
    Vascular risk factors, particularly vasospasm are believed to play a role in the pathogenesis of normal pressure glaucoma (NPG).
                        
    This study identified dysfunction of the systemic vascular endothelial cell in patients with NPG. The vascular endothelium modulates contractile responses to 5-HT and ET-1 in human subcutaneous resistance arteries.
                          
    This effect is lost in patients with NPG, indicating a selective defect in agonist mediated release of endothelium derived vasodilators. 
                                     
    Selective antagonists of 5-HT and ET-1 may hence help to prevent vasospasm in patients with NPG.        
                                                                                                                            

  • V A Parker, J Herrtage, NJC Sarkies (Dept. of Ophth, Addenbrooke’s Hosp.Trust, Cambridge, UK)
    Clinical comparison of the Keeler Pulsair 3000 with Goldmann applanation tonometry.
    BJO, Nov.2001: 85(11): 1303-1304.
                                
    A masked study was carried out on 150 eyes by two experienced tonometrists, who compared the mean of the Goldmann intraocular pressure (IOP) readings against the pulsair 3000 reading (average of four puffs).
                                                   
    It was found that the Pulsair 3000 provides an accurate and objective method of IOP measurements and is as accurate as Goldmann tonometry.
       

  • H.A. Quigley, N.G. Congdon, D.S. Friedman, (Wilmer Ophth. Inst. Johns Hopkins Univ. Shool of Medicine, Baltimore, USA).
    Glaucoma in China (and worldwide): changes in established thinking will decrease preventable blindness.
    BJO, 2001; 85; 1271-1273
      
    The authors emphasise some basic fundamental concepts, stressing that we should avoid treatment of those who would NEVER have lost vision in their lives, and who may be more threatened by treatment than by the natural course of the disease.
      
    People derived from north China, including native peoples of North America and Greenland, have a high prevalence of angle closure glaucoma (ACG).
       
    Contrary to previous teaching, two surveys suggest that prevalence of ACG is similar among some African and Hispanic populations as among Europeans i.e. About 1/5th the rate of open angle glaucoma (OAG) in these population.
      
    ACG deserves greater emphasis as it comprises a higher proportion of all those with glaucoma. ACG blinds many more people than OAG and may be more easily treated.
     
    Although the estimated numbers of those with ACG in China are only 30% higher than those with OAG, ACG blinds 10 times more people than DAG in absolute terms.
     
    Identifying narrow angles is not enough, as the proportion of those with occludable angles is nearly 10 times the proportion of those with damage to their optic nerve from glaucoma.
      
    Simple measures of anatomical size (chamber, axial length, etc.) have failed to differentiate effectively those who will get ACG.
     
    Though iridotomy is the present standard approach for the initial treatment of ACG, it is subject to abuse if too many eyes are treated which would never develop the disease.
      
    Research should identify how frequently iridotomy eliminates further need for treatment.
     
    The work of Foster and Johnson shows that only 20-25% of those with ACG develop acute attacks while the remainder continue to have a chronic asymptomatic disorder. ACG of the more chronic form and OAG are both identifiable by a similar diagnostic approach viz evaluation of the optic nerve and/or visual field.
      

  • N G Congdon, P J Foster, et al (Wilmer, Baltimore, USA)
    Biometric Gonioscopy and the Effects of Age, Race, and Sex on the Anterior Chamber Angle
    BJO, January 2002; 86(1); 18-22
      
    The authors describe a novel method for making measurements in the anterior chamber to compare the anterior chamber angles of people of European, African, and east Asian descent aged 40 years and over.
     
    In this study, 15 people of each sex were chosen from each decade from the 40s to the 70s from each of 3 racial groups – black, white, and Chinese Singaporeans. Biometric gomioscopy (BG) utilising a slit lamp mounted graticule was used to make measurements from the apparent iris insertion to Schwalbe’s line through a Goldmann one mirror goniolens.
     
    There was no significant difference in angle measurements between black, white and Chinese. At younger ages, Chinese appeared to have deeper angles than white or black people. The angles of older Chinese were significantly narrower.
     
    The apparently more rapid decline in angle width measurements with age among Chinese may be due to the higher prevalence of cataract or “creeping angle closure”.
      

 

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