Roxburgh Stuart, Ninewells Hospital and Medical School, Dundee, UK
The Conundrum of Sweet Hyperopia
Editorial -Br.I.Ophthalmoogy, 84(10); 1087-1089
A low degree of myopia (about-2D), is more common in metabolically stable adult diabetics, probably due to an increase in lens thickness and surface curvature.
There has been some controversy about the nature of the changes and underlying causes of transient refractory changes. It has been considered that myopia develops in hyperglycaemia and that following therapy there is an hyperopic shift. However, some investigators have suggested that acute changes may cause either myopia or hyperopia. The study by Okamoto et al in this issue of the BJO (p.1098) is helpful in clarifying some of these issues.
Out of multiple variable factors responsible, Okamoto et al report that the refractive changes are due to a change in the lens refractive index.
There is no knowledge of the biochemical changes occurring in the diabetic crystalline lens – any hypothesis is based on experimental studies. The lens membranes are permeable to glucose but much less to sugar alcohols such as sorbitol.
Hyperglycemia may affect the permeability of the lens membrane and may influence lens metabolism through yet unknown mechanisms.
Moll Annette C, Imhof Saskia M, Van Meeteren -Schouten Antoinette YN, Boers Maarten. (Dept.of Ophthalmology, Academic Hosp.Netherlands)
At what age could screening for familial retinoblastoma be stopped? A register based study 1945-98.
British Journal of Ophthalmology,2000, 84(10), p.1170-1172
Screening of children and siblings at risk for familial hereditary retinoblastoma is recommended until the age of 4 years, in order to detect retinoblastoma as early as possible.
Schmitz Sabine, Dick H Burkhard, Krummenauer Frank, Schwenn Oliver, Krist Romano. (Univ of Mainz, Germany)
Contrast sensitivity and glare disability by halogen light after monofocal and multifocal lens implantation.
Br.J Ophthalmol 2000, 84(10), p.1109-1112.
A new halogen glare test stimulating glare as seen with oncoming vehicle headlights was used to measure glare disability in patients implanted with multifocal and monofocal intraocular lenses (10Ls).
The results suggest NO difference in glare disability induced by halogen light similar to oncoming vehicle headlights for patients implanted with monofocal and multifocal IOLs.
Hammond C.J., Snieder Harold, Spector Tim D, Gilber C.E. (St. Thomas’s Hospital, London; Inst. Of Ophthalmology)
Factors affecting pupil size after dilatation: the Twin Eye Study.
Br J Opthalmology 2000;84:1173-1176.
Pupil size after mydriasis is largely genetically determined with a heritability of up to 80%.
506 twin pairs, 226 monozygotic (MZ) and 280 dizygotic (DZ) aged 49-79 were examined.
Dilated pupil size was more highly correlated in MZ compared with DZ twins.
Iris colour did NOT significantly contribute to the variance in dilatation.
Sharma S, Garg Prashant, Rao Gullapalli N. (LV Prasad Eye Institute; Hyderabad, India).
Patient characteristics, diagnosis, and treatment of non-contact lens related Acanthamoeba Keratitis.
Br.J Ophthalmology 2000; 84:1103-1108.
This study of 39 consecutive patients with a diagnosis of Acanthamoeba keratitis, is thought to be one of the largest series in non-contact lens wearers.
In such cases, disease progress is rapid, pathognomonic clinical features are rarely seen, and visual prognosis is poor.
Treatment with biguanides (PHMB i.e. polyhexamethylene biguanide, along with CHx i.e. chlorhexidine digluconate) singly (in 39.4% patients) and in combination (60.5% patients) was carried out.
Overall visual outcome was poor. Visual outcome in cases requiring tissue adhesive (five) and keratoplasty (three) was also poor.
Maria M van Genderen, Kinds Geert F, Riemslag Frans CC, Hennekam Raoul CM. (Institute of Visually Handicapped “Bartimeus”, Zeist, Netherlands and Academic Medical Centre)
Ocular features in Rubinstein-Taybi syndrome: investigation of 24 patients and review of the literature.
Br J Ophthalmology 2000; 84:1177-1184.
Twenty-four patients having Rubinstein-Taybi syndrome (RT) were selected for ophthalmological and electrophysiological examination.
Most frequently reported eye anomalies in literature are lacrimal duct obstruction, corneal abnormalities, congenital glaucoma, congenital cataract and colobomata.
In the above series, retinal abnormalities were found in 18 patients, where VEPs showed an abnormal waveform in 15 patients. ERGS were abnormal in 14 out of these 18 patients.
The high frequency of retinal dysfunction has not been described earlier.
Mulholland B, Marks M, Lightman S L, (Moorfields Eye Hospital, London, UK; Institute of Psychiatry, London; Institute of Ophthalmology, London).
Anterior uveitis and its relation to stress
Br.J.Opthalmology, 84(10); 1121-1124
The authors observed that some patients with recurrent acute anterior uveitis (RAAU) related recurrences of inflammation to psychological factors.
The study tested the hypothesis that stressful life effects may be associated with the onset of RAAU. It was found that stress is NOT involved in triggering the recurrence of idiopathic RAAU.
Kerkhoff FT, Rothova A, (Univ Hospital, Utrecht, Netherlands)
Bartonella henselae associated uveitis and HLA-B27
Br.J Opthalmol 2000;84(10):1125-1129.
Bartonella henselae, a Gram negative rod, was identified as the organism causing cat scratch disease (CSD). Ocular involvement in B.henselae infection has been reported to be the cause of Parinauld’s oculo-glandular syndrome, uveitis and neuroretinitis.
The authors have investigated the frequency of HLA-B27 in presumed ocular bartonellosis and have reported the clinical features and laboratory data of these patients.
SR Rathinam, P Namperumalsamy, E.T. Cunningham Jr. (Aravind Eye Hosp. & PG Inst, of Ophthalmology, Madurai, Tamil Nadu, India & F.I. Proctor Foundation and the Dept. of Ophthalmology UCSF, Med Centre, San Francisco, CA, USA)
Spontaneous cataract absorption in patients with leptospiral uveitis.
BJO 2000; 84: 1135-1141.
This article is a retrospective review of 394 eyes of 276 patients with seropositive leptospiral uveitis, seen in the uveitis clinic at Aravind Eye Hosp. Between January 1994 and December 1997.
Of these, 54 eyes (13.7%) had a final visual acuity of 20/40 or worse attributable to cataract formation.
Spontaneous cataract absorption was observed in 10 eyes (18.5%) of 8 patients (19.5%) and occurred from 6 weeks to 18 months, after the onset of cataract.
Out of 12035 consecutive NON-leptospiral, non-traumatic, uveitic, control patients seen during the same 4 yrs of the study, NONE showed spontaneous cataract absorption.
Spontaneous cataract absorption appears to be unique to this form of non-traumatic uveitis (occurring in patients with leptospirosis).
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.
DA Hollander, NJ Volpe, et al (Univ of Pennysylvania School of Medicine; Albert Einstein Hospital, Philadelphia)
Use of a portable head mounted perimetry system to assess bedside visual fields.
BJO 2000; 84: 1185-1190
The authors describe a head mounted, AUTOMATED perimetry system, which is portable and convenient for examining neurosurgical patients at their bedside in the perioperative period.
The method offers standardised, quantifiable testing with graphic results for follow-up examinations.
The device showed equal sensitivity to methods of confrontation field testing, in detecting field defects.
A Rosset, L Zografos, P Coucke, et al (Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; Univ of Lausanne, Switzerland)
Radiotherapy of Choroidal Metastases.
Radiother Oncol 46:263-268, 1998.
This is a review of the records of 58 consecutive patients undergoing external beam radiation therapy between 1970 and 1993. Patient ages ranged from 40 to 81 years. The primary tumor was breast carcinoma in 75%, lung carcinoma in 17%, gastrointestinal, gastrourinary, or unknown in the remainder. The median interval between the primary tumour and metastases was 55 months. Treatment consisted of megavoltage irradiation with a median prescribed dose of 35.5 Gy.
Complete response rate at 3 months or more after Rx was 53%. In 62% of patients, visual acuity was improved or stabilized. There were 5 complications: 3 cataracts, one retinopathy and one glaucoma.
Doses greater than 35.5 Gy provide significantly better tumor response and visual acuity. Whenever possible, a lens sparing technique should be used.
James C Lai, Sharon Fekrat, et al (Wilmer Ophthalmological Institute, The Johns Hopkins Medical Institution, Baltimore, Md)
Traumatic Hyphema in Children – Risk factors for Complications
Arch Ophthalmol, vol.119, Jan.2001, p64-70
Forty children were reviewed from consecutive in patient records (from July 1990 to December 1997) among patients admitted to the Wilmer Ophthalmological Institute, Baltimore, within 48 hrs of a closed globe injury leading to hyphaema.
The rate of secondary haemorrhage was statistically higher in the African American population. Sickle cell hemoglobinopathy increased the risk of intraocular pressure elevation, but did not seem to increase the risk of rebleeding beyond that associated with race.
Claudia S May (Baltimore Md)
Evidence for the Role of Sunlight Exposure in the Etiology of Choroidal Melanoma
Archives of Ophthal, vol.119, March 2001. Pp.430-431.
Exposure to solar UV-radiation has been implicated in the pathogenesis of cutaneous melanoma. This causal relationship is supported by the observation of the distribution of melanoma lesions in heavily SUN-exposed regions of the body.
Cutaneous and uveal melanomas both originate from a common cellular type viz the melanocyte.
Li et al at the Massachusetts Eye and Ear Infirmary documented the pattern of occurrence of choroidal melanoma on the fundus in 400 cases. A clear preponderance of tumours in particular at the foveal and inferotemporal parafoveal regions, along with decreasing tumour occurrence with increasing distance from the macula was noted. Posterior tumor distribution was particularly noticed in patients with lighter iris colour.
The cause of uveal melanoma is most likely multifactorial depending on host characteristics, genetic factors as well as environmental exposures. Further research is required to determine the biological mechanism of sunlight mediated tumorigenesis.
PA Crock, JD McKenzie, AM Nicoll, et al (John Hunter Children’s Hosp, Newcastle, England; Royal Children’s Hosp, Parkville Westmead, Australia, Starship Hosp. ,Auckland, New Zealand; et al )
Benign Intracranial Hypertension and Recombinant Growth Hormone Therapy in Australia and New Zealand.
Acta Paediatr 87:381-386, 1998.
Recombinant human growth hormone (rhGH) used for children with growth hormone deficiency (GHD) causes intracranial hypertension.
Baseline and periodic ophthalmic examinations are recommended especially if headache, nausea or oedema are present. On cessation of rhGH therapy, intracranial hypertension resolves. Later GH therapy can be restarted at a lower dose.
D.N. Parmar, A.Sofat, R. Bowman, et al (Department of Neurosciences, King’s College Hospital, London)
Visual prognostic value of the pattern electroretinogram in chiasmal compression.
Br.J.Ophthalmol 2000: 84: 1024-1026.
The visual loss caused by chiasmal (optic) compression by pituitary tumours may be transient or permanent. This is possibly related to the extent of irreversible retrograde degeneration of the retinal ganglion cells.
The pattern electroretinogram (PERG) N95 component is believed to rise in relation to retinal ganglion cell function and may be a potential prognostic indicator for visual function following decompressive surgery.
Records of 72 eyes from 36 patients were retrospectively analysed. It was concluded that the PERG is a useful visual prognostic indicator in the preoperative assessment of chiasmal compression.
Inoue K, Amano S et al (Univ. of Tokyo; Jichi Med School, Tochigi Prefecture, Japan)
Long-term Effects of Topical Cyclosporine A Treatment After Penetrating Keratoplasty
Jpn J Ophthalmol 44: 302-305, 2000
Allograft rejection is one of the most important factors affecting the clinical outcome of PKP, more so in high risk patients.
The immuno-suppressive effect of systemic Cyclosporin A (CsA) on allograft rejection after penetrating keratoplasty (PKP) has yet to be established.
The long-term effects of topical CsA for the suppression of corneal graft rejection were evaluated from the records of 83 patients who had undergone PKP and postoperative therapy with topical CsA. These 83 patients were compared with 85 patients who underwent PKP but did not receive CsA postoperatively.
The authors state that the risk of allograft rejection after PKP in high risk patients can be effectively reduced by CsA application.
Lisa R. Grillone and Rene Lanz
Drugs of Today, Vol.37 (4), April 2001, Pg. 245-255
Summary : Cytomegalovirus (CMV) retinitis can rapidly lead to blindness in patients with AIDS. Fomivirsen is a novel antisense drug.
It is a phosphorothioate oligonucleotide with a unique antisense mode of action. The 21-nucleotide sequence of fomivirsen is complementary to a sequence in mRNA of IE2 of human CMV. This region of mRNA encodes several proteins that are essential for the production of infectious CMV. Binding of fomivirsen to this target mRNA results in inhibition of IE2 protein synthesis, subsequently inhibiting viral replication.
In patients with AIDS, fomivirsen has been shown to provide a safe and effective treatment, for newly diagnosed, peripheral CMV retinitis or relapsed CMV retinitis unresponsive to other therapies.
No systemic adverse effects were seen. It is administered by intravitreal injection to ensure target-specific distribution. No drug is detected in systemic circulation. Local ocular adverse events were predominantly mild to moderate, transient and responded well to topical medications.
The dosing schedule is simple and combined with demonstrated safety and efficacy, fomivirsen is a valuable and convenient treatment, for patients with AIDS and newly diagnosed peripheral CMV retinitis or relapsed CMV retinitis unresponsive to other therapies.
Jerry Ware and Zaverio M. Ruggeri
Platelet Adhesion Receptors and their Participation in Hemostasis and Thrombosis
Drugs of Today, Vol.37 (4), April 2001, Pg. 265-274
Summary : Central to platelet function are a group of membrane surface receptors recognising a repertoire of adhesive substrates within the exposed subendothelial matrix. Circulating blood platelets adhere to the exposed subendothelial matrix resulting in platelet activation and recruitment of circulating platelets to the thrombogenic site.
Knowledge of the molecular role of the membrane receptors has resulted in the development of antagonists behaving as very selective antithrombotic agents. First generation of antiplatelet compounds that specifically block platelet membrane receptors have proved effective clinically. Most widely studied drugs are those that block the platelet integrin receptor aIIbb3. Other platelet targets present an opportunity for 2nd generation of antiplatelet receptor drugs with even more specialized inhibitory properties.
The various platelet receptors are integrin receptors like GPIIb/IIIa and GPIa/IIa. GPVI is a platelet receptor belonging to the immunoglobulin superfamily GPIb/IX/V complex is composed of 4 distinct gene products.
An issue to consider in future whether the untargeted repertoire of receptors, such as the collagen receptors or the GPIb/IX/V receptor might provide some therapeutic advantage for development of 2nd generation antithrombotics. The platelet GPIb/IX/V complex is the sole receptor supporting the initial tethering event of the platelet to the damaged surfaces, under flow conditions commonly found in small arteries and arterioles.
It is conceivable that targeting an individual receptor functioning under such defined rheological conditions might provide certain pharmacological advantages owing to the inability of the inhibitor to block hemostasis in other areas of circulation.
An example would be an antagonist specific to the arterial circulation that has no hemostatic effect in the venous circulation. Prominent platelet receptors have been identified and many of the experimental models both in vitro and in vivo have been developed. Thus, new opportunities exist for further development of antithrombotics in the new millennium.