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.
Zainah Alsagoff, Donald T H Tan, S-P Chee, (Singapore National Eye Centre, Singapore).
Necrotising scleritis after bare sclera excision of pterygium.
Br J Ophthalmol, 2000; 84:1050-1052.
Surgically induced necroitising scleritis (SINS) has been reported to occur after cataract extraction, trabeculectomy, squint surgery, and surgery for retinal detachment. Typically, it presents as a focal area of intense scleral inflammation occurring adjacent to the site of the surgical incision.
The authors conclude that bare sclera pterygium excision CAN cause surgically induced necrotising scleritis years after the surgery.
Peter R Laibson
Corneal Ocular Viral Diseases.
Editor- Year Book of Ophthalmology 2000,p.91
Acute dendritic and geographic ulcers are treated with topical antiviral agents.
Once disciform or necrotizing stromal keratitis occur, topical steroids are added. Herpetic iridocyclitis is treated with topical agents as well as ORAL acyclovir.
To prevent recurrence, 400mg of oral acyclovir twice a day are given for at least one year. It is important to check the kidney functions of patients receiving long term acyclovir by screening blood-urea nitrogen test, creatinine level test or both.
Newer antiviral agents have not been fully investigated..
Sankaridurg PR, Sweeney DF, Sharma S, et al (Univ of New South Wales, Sydney, Australia; LV Prasad Eye Inst, Hyderabad, India)
Adverse Events with Extended Wear of Disposable Hydrogels: Results for the first 13 months of Lens Wear.
Ophthalmology 106: 1671-1680, 1999.
Disposable hydrogel lenses introduced in 1988, caused renewed interest in extended wear. Regular lens replacement was advised in order to reduce potential for adverse reactions.
Three hundred thirty NEW contact lens wearers aged 16 to 39 years were studied over a period of three and a half years.
Most of the adverse reactions occurred in the first 13 months of extended wear in 102 participants (out of a total of 137).
In order of rate of incidence the following adverse reactions were noted.
Corneal infiltrates, contact lens papillary conjunctivitis, neovascularization and corneal wrinkling; corneal striae and superior epithelial arcuate lesions, blepharokeratoconjunctivitis, and viral keratoconjunctivitis.
No cases of infectious keratitis occurred. Two isolated events of infiltrative keratitis occurred, resulting in scarring. Best corrected visual acuity was not reduced in any of the patients.
Better materials and design are necessary to make extended wear a successful method.
Threlfall TJ, English DR (Univ of Western Australia, Perth)
Sun Exposure and Pterygium of the Eye: A Dose- Response Curve
Am J Ophthalmol 128: 280-287, 1999
Several factors may contribute to pterygium formation. These are hereditary factors, dust, wind, heat, infection, inflammation and sunlight.
The authors studied 285 patients to establish the association between sunexposure and pterygium. They conclude that pterygium is strongly associated with ocular sun exposure. Ocular protection at all ages is beneficial.
Dinh R, Rapuano CJ, Cohen EJ, et al (Wills Eye Hosp, Philadelphia)
Recurrence of Corneal Dystrophy After Excimer Laser Phototherapeutic Keratectomy
Ophthalmology 106: 1490-1497, 1999.
Anterior corneal dystrophies before and after penetrating keratoplasty have been treated with phototherapeutic keratectomy (PTK).
The recurrence of corneal dystrophies after excimer laser phototherapeutic keratectomy was evaluated. PTK can restore and preserve useful vision for a significant length of time. Even though recurrence is likely after PTK, retreatment with PTK can be successful.
HK Soong, Katz DG, Farjo AA, et al (Univ of Michigan, Ann Arbor)
Central Lamellar Keratoplasty for Optical Indications
Cornea 18: 249-256, 1999
The use of Lamellar Keratoplasty (LKP) is limited by graft-host interface problems, astigmastism, and a difficult operative technique.
The outcomes of LKP done at one centre in the past 19 years were analysed. The outcomes of LKP may be improved by removing as much recipient corneal stroma as possible. The use of an automated keratome and raising eyebank standards for accepting LKP donor tissue may improve the results of LKP.
Beck RW, Gal RL, Mannis MJ, et al (Jaeb Ctr for Health Research, Tampa, Fla; Univ of California, Davis; Univ of Minnesota, Minneapolis; et al)
Is Donor Age an Important Determinant of Graft Survival ?
Cornea 18: 503-510, 1999
Many surgeons today do not use a cornea from donors older than 60 years. However, the available evidence suggests that the age of cornea donors is not a strong predictor of the outcome of keratoplasty.
Garg P, Sharma S, Rao GN (Sight Savers’ Corneal Training Centre, Hyderabad, India; LV Prasad Eye Inst, Hyderabad, India)
Ciprofloxacin-Resistant Pseudomonas Keratitis
Ophthalmology 106: 1319-1323, 1999
Medical and microbiology records of 141 patients with culture-proved Pseudomonas Keratitis, seen between 1991 and 1998 were reviewed.
The study analyzed ciprofloxacin resistance of corneal isolates of Pseudomonas, and clinical response to topical treatment in patients with ciprofloxacin resistant Pseudomonas Keratitis (in whom medical treatment was begun with 0.3% ciprofloxacin).
Since true ciprofloxacin resistance is emerging among pseudomonas isolates, empirical treatment of infectious keratitis with ciprofloxacin monotherapy should be reviewed critically.
Sudesh S, Cohen E, Rapuano CJ, et al (Wills Eyes Hosp, Philadelphia)
Corneal Toxicity Associated with Latanoprost
Arch Ophthalmol 117:539-540, 1999
These are case reports of 2 women and 2 men who developed dendritiform corneal lesions when latanoprost was added to the medication regimen. The lesions resolved when the drug was discontinued. Diabetic patients may be more susceptible to this side-effects of latanoprost.
Mckibbin M, Isaacs JD, Morrell AJ (St Jamess Univ, Leeds, England)
Incidence of Corneal Melting in Association with Systemic Disease in the Yorkshire Region, 1995.
Br. J. Ophthalmol 83: 941-943, 1999
Twenty-seven patients with a diagnosis of peripheral or central corneal melting were identified between January 1995 and December 1997. The most commonly associated systemic diseases were rheumatoid arthritis (RA) and Wegeneres granulomatosis. Corneal melting occurred as a late complication of RA, but occurred during early Wegeners granulomatosis.
Terry MA, Ousley PJ (Oregon Research Lab, Portland; Devers Eye Inst, Portland, Ore)
New Screening Methods for Donor Eye-bank Eyes
Cornea 18 : 430-436, 1999
Current screening techniques for keratoplasty do not always exclude corneas with abnormal topography. Corneal thickness maps using the orbscan were found useful in donor tissue screening.
Corneal thickness maps were generated in a study of 40 eyes (from the eye bank), using the orbscan. Results from 2 eyes from a donor with photorefractive keratectomy (PRK) and 2 from a donor with keratoconus were compared with normal donor eye results.
Donor eyes with known refractive surgery or corneal diseases, which are undetectable by the slit lamp, can be analyzed with the orbscan, in order to improve keratoplasty results.
Manche EE, Holland GN, Maloney RK (Stanford Univ Calif; Univ of California at Los Angeles; Maloney Vision Inst, Los Angeles).
Deep Lamellar Keratoplasty Using Viscoelastic Dissection.
Arch Ophthalmol 117 : 1561-1565, 1999
This technique was carried out in four patients, where a lamellar corneal dissection was done, along with removal of stromal tissue to facilitate visualization of anterior segment structures before performing penetrating keratoplasty. The procedure facilitated separation of iridocorneal adhesions as the Descemet membrane was incised. There were no complications. This procedure was found to be particularly useful for keratoconus and stromal dystrophies.
De Quan Li, Sao-Bing Lee, et al (Dept. of Ophth, Bascom Palmer Eye Inst. and Depts of Medicine and Cell Biology & Anatomy, Univ of Miami School of Medicine)
Overexpression of Collagenase (MMP-1) and Stromelysin (MMP-3) by Pterygium Head Fibroblasts.
Arch Ophthalmol, vol.119, Jan.2001, pg.71-80
The balance between matrix metalloproteinase (MMPS) and the tissue inhibitors of metalloproteinases (TIMPS) determines the extent of degradation and remodelling of connective tissue.
Pterygium head fibroblasts express increased mRNA, protein and activities of MMP-1 and MMP-3.
The authors conclude that the over expression of MMP-1 and MMP-3, (previously linked with UV exposure in dermal fibroblasts, explaining the pathologic finding of elastotic degeneration), may lead to alteration of pterygium head fibroblasts by UV light. This is in turn might be responsible for corneal invasion.
V A Smith, H Rishmawi, H Hussein, D L Easty (Univ. of Bristol, Bristol Eye Hospital, UK)
Tear film MMP accumulation and corneal disease.
Br J Ophthalmol. 2001: 85: 147-153.
Matrix Metalloproteinases (MMPs) accumulate in tears of patients with active peripheral ulcerative keratitis (PUK). These enzymes are a family of zinc and calcium ion dependent enzymes, which participate in tissue remodelling. Pathologically they cause disruption or disintegration of extracellular matrices.
The authors conclude that MMPs that accumulate in tears are mainly derived from granulocytes. This may be effected by autoimmune diseases involving ocular tissue or by an inflammatory response induced by ocular disease.
Detectable amounts of enzymes were also found in tears of patients with keratocomus, with associated atopic disease, patients undergoing treatment for herpetic eye disease and patients with systemic and nonsystemic dry eye disease.
K Nakamura, D Kurosaka et al (Keio Univ School of Medicine, Tokyo, Japan)
Intact Corneal Epithelium is essential for the prevention of stromal haze after laser assisted in situ keratomileusis.
Br.J Ophthal. February 2001, 85, 209-213.
This experimental study on rabbits compared denuded epithelium alone, photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and LASIK with denuded epithelium.
Immunohistochemical methods were used to detect alpha smooth muscle actin (a-SMA), which is a marker for myofibroblastic cells, and collagen in subepithelial corneal tissues.
The authors concluded that the intact corneal epithelium may play a vital role in curbing subepithelial haze.
H-M Woo, MS Kim, et al (The Catholic Univ of Korea, Korea)
Effects of amniotic membrane on epithelial wound healing and stromal remodelling after excimer laser keratectomy in rabbit cornea.
Br J Ophthalmol, March 2001: 85, 345-349
This is an experimental study carried out in 40 rabbits, in whom a wound was created with an excimer laser. One eye was randomly chosen to be covered by the amniotic membrane (AM) while the other served as a control.
The authors concluded that the use of AM as a cover on the corneal wound created by excimer laser surgery may induce rapid epithelial healing with less inflammatory response. The AM may inhibit the irregular synthesis of stromal collagen which is associated with corneal haze.
VM Borderie, V Sabolic, et al (Banque de cornees de I’Establissement Francais du Sang, Ile-de-France, Hopital Saint Antoine, Paris, France).
Screening human donor corneas during organ culture for the presence of guttae.
Br. J Ophthal.March 2001, 85: 272-276
Cornea guttata can be detected during organ culture by means of light microscopy. There is associated decrease in endothelial cell figure co-efficient and cell density. The presence of grouped guttae is associated with poorer graft survival and also more frequent stage 3 corneas guttata in the graft after keratoplasty.
AS Forseto, CM Francesconi, RAM Nose , et al [Eye Clinic Day Hosp, Sao Paulo, Brazil]
Laser in Situ Keratomileusis to Correct Refractive Errors After Keratoplasty
J Cataract Refract Surg 25: 479-485, 1999
The result of LASIK in 22 eyes of 19 patients [with a history of keratoplasty] were reported. Ninety-one percent of eyes had had keratoconus before keratoplasty was done. Penetrating keratoplasty [PK] was done in 82% of eyes, and lamellar in 18%.
LASIK was performed a mean of 5 years after keratoplasty. The authors found that 55% patients achieved uncorrected visual acuity of at least 20/40. There were no serious complications such as significant endothelial cell loss or keratoplasty wound dehiscence.
The authors however state that long-term follow-up is required to firmly establish the efficacy of this procedure.
L J Muller, E Pels, GFJM Vrensen (Netherlands Ophthalmic Research Institute, Amsterdam)
The specific architecture of the anterior stroma accounts for maintenance of corneal curvature.
Br J Ophthal 2001; 85: 437-443.
The human corneal stroma was analysed in extreme hydration to discover if its structure is responsible for corneal stability.
It was found that the rigidity of the most anterior part of the corneal stroma in extreme hydration states, points to an important role in maintenance of corneal curvature.
Since a large part of this rigid anterior part of the stroma is either removed (as in PRK) or intersected (as in LASIK), it is possible that in the long run patients who undergo refractive surgery may be faced with optical problems.
MP Upadhyay et al (Univ. Institute of Medicine & Teaching Hosp.) Kathmandu Nepal; Proctor Foundation for Research in Ophthalmology Univ of California, San Francisco, CA)
The Bhaktapur eye study : Ocular Trauma and Antibiotic prophylaxis for the prevention of corneal ulceration in Nepal
Br J Ophthal, 2001; 85, 388-392.
Over a two-year period there were 1248 cases of ocular trauma and 551 cases of corneal abrasion. The number of clinically documented corneal ulcers was 558.
The study conclusively showed that post-traumatic corneal ulceration could be prevented by topical application of 1% chloramphenicol ointment. Maximum benefit is obtained if prophylactic treatment is started within 18 hours after injury.
D C Herman, DO Hodge, et al (Depts. Of Ophthal. & Biostats – Mayo Clinic, Rochesther, Minnesota)
Increased corneal thickness in patiets with ocular hypertension
Archives of Ophthal., vol.119, March 2001: 334- 336.
Although less likely to be affected by scleral rigidity applanation tension can be affected by corneal thickness.
Central corneal thickness > 0.520mm causes true intraoculation pressure to be overestimated while using the technique of applanation tonometry.
This increased corneal thickness may modify the risk for progression to glaucoma in patients with ocular hypertension.
Khalid F Tabbara (Dept. of Ophthal, King Saud Univ, Riyadh Saudi Arabia)
Tear Tryptase in Vernal Keratoconjunctivitis
Arch.Ophthal. Vol.119, March 2001, 338-342
A total of 20 patients, 7 years or older, with vernal keratoconjunctivitis (VKC) were studied. Tear samples for tryptase determination were collected before and 2 weeks after treatment with 4% disodium cromoglycate eye-drops and 0.1% fluorometholone eye-drops.
Control tear samples were collected from 20 normal control patients for tryptase determination.
It was found that patients with severe VKC had high levels of tryptase in tears. Following treatment, the level of tryptase in tears decreased significantly.
C K Patel, R Hanson et al (Oxford Eye Hospital, Radcliffe Infirmary)
Late Dislocation of a LASIK Flap Caused by a Fingernail
Arch Ophthalmol, vol.119, March 2001, pg.447-450
This is a case report of a 28 yr.old white lady who underwent uncomplicated bilateral LASIK. Ten months following surgery, her fingernail brushed the left eye while she was removing a sweater. This resulted in painful displacement of the corneal cap.
After repositioning the cap (under topical and sub-Tenon anaesthesia) it was found that the cap had everted, the lower edge of the nasal hinge had torn, it had twisted about the original hinge and one of its edges had folded over.
The stromal bed and cap were debrided and Three 10-0 nylon sutures were used to secure the cap. Five days later debris was detected between the cap and corneal stroma, suggestive of epithelial in growth.
Forty-three days postoperatively, irregular astigmatism reduced unaided visual acuity to 20/200. This later recovered to 20/40 following removal of a small central area of corneal stroma, scraping of the residual cap area and application of a bandage lens. The patient is being managed conservatively. The authors make the following interesting comments:
Recent reviews of Lasik state that cap dislocation occurs in 0.7% to 5.8% cases.
Debridement of edematous corneal epithelium during vitrectomy has resulted in iatrogenic cap dislocation.
Corneal integrity is never fully restored after creation of a LASIK flap. Flap dislocation as a potential delayed complication should be discussed as part of informed consent prior to surgery.
Lasik should be contraindicated in patients with a high risk of sustaining glancing corneal injuries, as in rugby players.
Ying Qian, Iva Dekaris et al. (Schepens Eye Research Inst, Dept. of Ophthalmology, Howard Medical School Boston, Mass
Topical Soluble Tumor Necrosis Factor Receptor Type I Suppresses Ocular Chemokine Gene Expression and Rejection of Allogeneic Corneal Transplants)
Arch of Ophthal, Dec.2000: 118, pp.1666-1671
This is a study of survival of murine orthotopic corneal transplants, following the use of topical soluble tumor necrosis factor receptor type 1 (sTNFR-1) and on ocular chemokine gene expression after corneal transplantation.
It was found that topical treatment with sTNFR-1 promotes the acceptance of allogeneic corneal grafts and inhibits gene expression 2 chemokines which are associated with graft rejection.
Thus, topical treatment with s-TNFR-1 would reduced corneal allograft rejection without the use of potentially toxic immunosuppressive drugs.
Joshua Ben-num (Tzriffin, Israel)
Photorefractive Keractectomy and Laser in situ Keratomileusis: A Word From the Devil’s Advocate.
Archives of Ophthalmol. Vol.118, Dec.2000, p.1706-1707.
At a time when there has been a significant improvement in the technology of treatment of refractive errors by laser in-situ keratomileusis (LASIK), this author has issued a very timely warning both to patients undergoing the procedure and to the people performing LASIK.
The procedure involves a laser beam at 193nm that evaporates part of the cornea, breaking cells and molecules to create the smooth corneal surface necessary for best optical results.
The creation of free radicals, is an inseparable part of the cornea reshaping process.
Both photorefractive keratectomy (PRK) and LASIK are known to cause keratocyte apoptosis in the corneae of laboratory animals and hence, though there is no short-term damage, long-term damage must be considered.
These procedures are also known to have caused biochemical and ultrastructural modifications in the lens, both of which are markers of cataractogenesis. The vitreous base, located just posterior to the lens may be affected by the same process that affects the cornea, anterior chamber and the lens. Free radicals damage the vitreous collagen, leading to vitreous liquefaction. They have also been shown to promote tumours.
PRK might initiate a cascade of events leading to slowly developing abnormalities of the cornea, lens, vitreous retina and choroid.
On one hand there is a marked increase in the popularity of LASIK promulgated by massive advertisement. Hence there is an urgent need for intensive research into the potential threats to ocular function caused by LASIK which may occur in patients decades after the initial procedure, slowly but almost surely.
Noriko Koizumi, T Inatomi, et al (Kyoto Japan)
Cultivated Corneal Epithelial Transplantation for Ocular Surface Reconstruction in Acute Phase of Stevens-Johnson Syndrome.
Arch Opthalmol, vol.119, Feb.2001,pg.298-300
In the acute phase of Stevens-Johnson Syndrome (SJS) (erythema multiform), patients may develop bilateral blindness due to a lack of corneal stem cells, corneal scarring and subconjunctival fibrosis.
Prognosis of keratoplasty in the acute phase is poor because of the difficulty of overcoming the severe inflammatory reaction and allograft rejection.
Recently, attention has focused on cultivated corneal epithelial transplantation as a new approach for ocular surface reconstruction in limbal deficient disorders.
The authors have successfully established a surgical system for cultivated corneal limbal epithelium transplantation in rabbits,using amniotic membrane as a carrier.
They report two cases (32 yr and 21-yrold men) who had had SJS for 3 months. They used cultivated allocorneal epithelial transplantation to cover the ocular surfaces with clear epithelium.
The inflammatory reaction subsided and the authors found this method as an effective ocular surface reconstruction technique for acute phase SJS.
GW Zaidman, A Billingsley (Westchester County Med Ctr, Valhalla, NY) Corneal
Impression Test for the Diagnosis of Acute Rabies Encephalitis.
Ophthalmology, 105: 249-251, 1998.
This is a case report of a 13 yr. old girl who was admitted with a diagnosis of acute encephalitis of unknown origin. After 72 hours (during which other investigations were inconclusive of the diagnosis), a corneal impression test was performed. Within 24 hrs, the CIT was reported positive for rabies antigen.
The corneal impression test (CIT) should help in the early diagnosis of rabies.
WA Lyle, GJC Jin (Eye Inst of Utah, Salt Lake City)
Hyperopic Automated Lamellar Keratoplasty: Complications and Visual Results.
Arch Ophthalmol 116:425-428, 1998.
The use of hyperopic automatted lamellar keratoplasty should be discouraged because of its long-term instability and high incidence of iatrogenic keratoconus especially true for consecutive hyeropia after radial keratotomy.
RJ Smith, RK Maloney (Jules Stein Eye Inst, Los Angeles; Univ of California, Los Angeles)
Diffuse Lamellar Keratitis: A New Syndrome in Lamellar Refractive Surgery.
Ophthalmology 105: 1721-1726, 1998.
After lamellar refractive surgery, infectious keratitis can occur, which can be confused with the self-limiting syndrome, diffuse lamellar keratitis.
Noninfectious diffuse lamellar keratitis (also called – Sands of the Sahara syndrome) is a syndrome of unknown origin following lamellar refractive surgery. The condition begins 2 to 6 days after surgery and resolves within 2 weeks – it may be associated with pain or photophobia. The treatment of choice is an increase in topical steroids and close follow-up.
Beck RW, for the Herpetic Eye Disease Study Group (Jaeb Ctr for Health Research, Tampa, Fla)
Acyclovir for the Prevention of recurrent Herpes Simplex Virus Eye Disease.
N Engl J Med 339: 300-306, 1998.
One year of treatment with oral acyclovir after the resolution of ocular HSV disease, decreases the rate of recurrent ocular HSV disease and orofacial HSV disease. Such treatment is especially important for patients with a history of HSV stromal keratitis as it can prevent recurrent episodes and visual loss.
Cornea Dry Eye
ME Sterm. RW Beuerman, RI Fox, et al (Allergan, Irvine, Calif; LSU Eye Ctr, New Orleans, La; Scripps Research Found, La Jolla, Calif; et al )
The Pathology of Dry Eye: The Interaction Between the Ocular Surface and Lacrimal Glands.
Cornea 17:584-589, 1998.
Dry eye symptoms may result from systemic auto-immune diseases or may occur locally because of reduction in systemic androgen support to the lacrimal gland. This often occurs in menopausal women. Sex hormones significantly affect lacrimal gland function.
Androgens exert essential, specific effects on maintenance of normal lacrimal gland function and suppress inflammation.
When systemic androgen levels drop below threshold support levels, proinflammatory cytokine secretion interferes with the tearing reflex. Atrophic changes in the glandular tissue promote antigen presentation at the surface of the acinar cells. Lymphocytic infiltration of the gland increases.
Topical ophthalmic cyclosporine-A and steroids can improve a dry-eye by eliminating conjunctival and lacrimal gland lymphocytic infiltrates. Androgens, both systemic and topical, may help.
U Rehany, S Rumelt (Western Galilee-Nahariya Med Ctr, Israel):
Ocular Trauma Following Penetrating Keratoplasty: Incidence, Outcome, and Postoperative Recommendations.
Arch Ophthalmol 116:1282-1286, 1998
The surgical wound created by penetrating keratoplasty (PK) increases vulnerability to contusive trauma. The incidence, causative factors, management and visual outcome of ocular trauma after PK were documented.
In view of the long-term vulnerability of the graft wound, patients should wear protective eyewear, and they should be instructed to avoid strenuous activity and high-risk environment.
GS Schwartz, EJ Holland (Associated Eye Care, Stillwater, Minn; Univ of Minnesota, Minneapolis).
Iatrogenic Limbal Stem Cell Deficiency.
Cornea 17: 31-37, 1998.
Deficiencies in the stem cells (SCs) that renew the corneal epithelium can lead to scarring, ulceration and loss of vision.
A group of 14 eyes in 12 patients with SC deficiency without known cause was reviewed. All patients were affected at sites of prior limbal surgical incision. External disease and extended topical medication make these cells more easily damaged.
Removing the abnormal corneal epithelium to allow re-epithelialization from the normal corneal epithelium rather than from the abnormal limbal SC area, may hasten resolution of this problem.
MJF Orhdahl, PP Fagerholm (St Erik Eye Hosp, Stockholm; Karolinska Inst, Stockholm)
Phototherapeutic Keratectomy for Map-Dot-Fingerprint Corneal Dystrophy.
Cornea 17:595-599, 1998.
Map-dot-fingerprint (MDF) dystrophy is the commonest corneal dystrophy causing transient or permanent reduction in visual acuity, sometimes combined with ghost images or subjective monocular diplopia. The latter symptoms result from irregular astigmatism and abnormal tear break-up.
Excimer laser photoablation appears to be effective, safe and stable in eyes with MDF dystrophy.
R H Kennedy, N Hogan, et al (Menlo Park, California)
Eye Banking and Screening for Creutzfeldt – Jakob Disease
Arch.Ophth. Vol.119, May 2001, p.721-26
From 45,000 cornea donors in the US each year, only 1.3 might be expected to have CJD. Most of the estimated risk is due to preclinical (asymptomatic) disease.
Screening for symptoms of CJD would have minimal impact on safety, but donor supply would be reduced.
Toshiko Matsuo (Okayama Univ.Med School, Japan)
Trehalose protects corneal epithelial cells from death by drying.
Br. J Ophthal, May 2001, 85 p.610-612
Trehalose at 50,100 and 200 mM protected corneal epithelial cells in culture from death by desiccation.
The author postulates that trehalose could be used as a potential new eye drop for dry eye syndrome.
F Schaefer, O Bruttin et al (Jules Gonin Eye Hosp., Univ. of Lausanne, Switzerland)
Bacterial keratitis: a prospective clinical and microbiological study
Br J Opthalmology: 2001; 85. 842-847
Eighty-five consecutive patients with bacterial keratitis (mean age 44.3 years) were enrolled between March 1 1997 and November 30 1998 i.e. 21 months.
The following risk factors were identified. Contact lens wear (36%), blepharitis (21%), trauma (20%), xerophthalmia (15%), keratopathies (8%), and eyelid abnormalities (6%).
The most commonly isolated bacteria were Staphylococcus epidermidis 40%, Staphylococcus aureus 22%, Streptococcus pneumoniae 8%, other Streptococcus species 5%, Pseudomonas 9%, Moraxella and Serratia marcescens 5% each; Bacillus Corynebacterium, Alcaligenes xyloxidans, Morganella morganii, and Haemophilus influenza 1% each.
1-15% of strains were resistant to fluoroquinolones, 13-22% to aminoglycosides, 37% to cefazolin, 18% to chloramphenicol, 54% to polymyxin B, 51% to fusidic acid, and 45% to bacitracin.
S. Tyring, R Engst, et al (Collaborative Famciclovir Ophthalmic Zoster Research Group)
Famciclovir for ophthalmic zoster: a randomized aciclovir controlled study.
Br.J.Ophthal, May 2001; 85: 576-581.
Famciclovir 500mg three times daily was well tolerated and demonstrated efficacy similar to aciclovir 800mg five times daily.
Apart from a more convenient dose regimen, this study found no significant advantage of famciclovir over acyclovir.
P-Y Lin, C-C Wu, et al (National Yang Ming University, Dept. of Ophthalmology, Taipei Veterans General Hospital, Taiwan, ROC)
Combined phototherapeutic keratectomy and therapeutic contact lens for recurrent erosions in bullous keratopathy
B.J.O. Aug. 2001; 85: 908-911
Excimer laser phototherapeutic keratectomy (PTK) was performed in 8 eyes with painful recurrent corneal erosions (RCE) secondary to bullous keratopathy (BK), where no visual benefit was expected, if penetrating keratoplasty were to be done. After PTK, therapeutic contact lenses were applied for 3 months.
All patients experienced relief of pain after the epithelium healed. No infection or other complications were seen.
The authors conclude that PTK with deep ablation and adjunctive therapeutic contact lens is an easy and effective treatment for patients with bullous keratopathy who have poor visual potential.
Colin J, Cochener B, Savary G, et al (Brest Univ, France)
Correcting Keratoconus With Intracorneal Rings
J Cataract Refract Surg 26: 1117-1122, 2000
The use of intra stromal corneal rings (Intacs) may delay and avoid the need for penetrating keratoplasty (PKP) in patients with contact lens (CL) intolerance who have clear cornea keratoconus.
Intacs can change the corneal shape in patients with low myopia by effectively flattening the central cornea.
The intacs do not eliminate the keratoconus, but decrease the corneal abnormality to achieve acceptable visual acuity, thereby delaying or eliminating the need for PKP.
Jost Hillenkamp, Thomas Reinhard, et al (Department of Ophthalmology, The Rayne Institute, St Thomas’ Hospital, London)
Topical Treatment of Acute Adenoviral Keratoconjunctivitis With 0.2% Cidofovir and 1% Cyclosporine
A Controlled Clinical Pilot Study
Arch Ophthalmol., October 2001,Vol. 119(10) Pg. 1487-1491
This was a randomized, controlled, double-masked study conducted on 39 patients with acute adenoviral keratoconjunctivitis of recent onset.
Patients were divided into 4 groups (1) cidofovir qid, (2) cyclosporine qid, (3) cidofovir+cyclosporine qid, and (4) sodium chloride qid (control). The diagnosis was confirmed using adenoviral polymerase chain reaction from conjunctival swabs. Subjective improvement of local symptoms was accelerated in the cyclosporine group.
The authors conclude that the use of cidofovir, cyclosporine or both did not accelerate the improvement of clinical symptoms of acute adenoviral keratoconjunctivitis compared with the natural course of infection.
The effect of a higher concentration of topical cidofovir with and without cyclosporine requires further investigation in a larger group of patients.
Rosenthal P, Cotter JM, Baum J (Boston Found for Sight; Boston Eye Associates; Harvard Med School, Boston)
Treatment of Persistent Corneal Epithelial Defect With Extended Wear of a Fluid-Ventilated Gas-Permeable Scleral Contact Lens.
Am J Opthalmol 130: 33-41, 2000
Risk factors contributing to the development of persistent corneal epithelial defects (after corneal abrasion) are corneal hypoaesthesia, limbal stem cell deficiency and diabetes.
Eyelid patching extended wear of soft contact lenses, lubricants and tarsorrhaphy can be used to enhance reepithelialization.
The authors selected 13 patients who had persistent corneal epithelial defects and had failed to respond to previous treatments or had a large epithelial defect after penetrating keratoplasty.
All patients were managed with an extended-wear, gas-permeable scleral lens which were specially designed to prevent intrusion of large air-bubbles under the optic.
Healing occurred in 5 of 7 defects associated with Stevens-Johnson syndrome with most cases re-epithelializing within 7 days. Of 7 defects not related to Stevens-Johnson syndrome, 5 re-epithelialized within 36 hours to 36 days. 6 of 14 defects failed to heal with extended wear lens.
The key features promoting healing include an adequate oxygen supply, continuous aqueous interface and protection of the fragile epithelium. There is a significant risk of microbial keratitis.
Patients should be converted from extended-wear to daily-wear lenses as soon as possible after the epithelium has remained intact for at least 24 hours.
Beck RW, for the Herpetic Eye Disease Study Group (Jaeb Ctr for Health Research, Tampa, Fla; et al)
Oral Acyclovir for Herpes Simplex Virus Eye Disease: Effect on Prevention of Epithelial Keratitis and Stromal Keratitis.
Arch Ophthalmol 118: 1030-1036, 2000
In a randomized placebo-controlled trial, the authors found that treatment with oral acyclovir, 400mg twice daily for one year, reduced the risk of recurrence of ocular herpes simplex virus (HSV) disease by 45%.
Treatment reduces the risk of ocular surface recurrences such as blepharitis, conjunctivitis, and epithelial keratitis, as well as stromal keratitis and keratouveitis.
Though all patients at risk of recurrent ocular HSV can be treated with acyclovir, patients with a previous history of stromal keratitis should be specifically targeted.
Moss SE, Klein R, Klein BEK (Univ of Wisconsin, Madison)
Prevalence of and Risk Factors for Dry Eye Syndrome
Arch Ophthalmol 118: 1264-1268, 2000
3722 residents of Beaver Dam, Wisconsin, aged 48 to 91 years were included in this study, to analyze the prevalence of and risk factors for dry eye syndrome.
Overall prevalence of dry eye syndrome was 14.4%; 8.4% in patients < 60 years age and 19% in patients > 80 years age.
Prevalence in women was 16.7%; men – 11.4%.
Factors independently associated with dry eye syndrome were history of arthritis, past smoking, current smoking, caffeine use, thyroid disease, gout, total cholesterol to high density lipoprotein cholesterol ratio, diabetes, past or current multivitamin use.
Dry eye syndrome was unrelated to body mass, blood pressure, white blood cell count, hematocrit, osteoporosis stroke, cardiovascular disease, allergy, use of drying medications, alcohol consumption, time spent outdoors, maculopathy, central cataract or lens surgery.
The authors have identified new risk factors including cholesterol status, smoking and multivitamin use. The use of caffeine – a xanthine – may have a protective effect.
Bonini S, Lambiase A, et al (Univ of Rome; Natl Research Council, Rome; Associazione Fatebenefratelli per la Ricerca, Rome; et al)
Vernal Keratoconjunctivitis Revisited: A Case Series of 195 Patients With Long-term Followup.
Ophthalmology 107: 1157-1163, 2000.
The patients included in this study, showed a preponderance of males (3:1) with a mean age of 7 years at symptom onset.
Over 60% patients reported year round relapses. Nearly 25% patients reported no remission since symptom onset.
The most frequent clinical findings were conjunctival and episcleral hyperemia along with superficial punctate keratitis. Other findings were sticky mucous discharge, Horner-Trantas’ dots, corneal neovascularization and corneal shield ulcers.
Eosinophils were detected in 85% patients, in the epithelium of corneal scrapings.
High numbers of AAI-positive mast cells, activated eosinophils and lymphocytes were found in tarsal and bulbar conjunctival biopsy.
85% patients required a topical ophthalmic steroid at some time during their treatment. 31% reported no improvement and 3% said their condition had worsened. Patients with more severe papillae were more likely to have persistent or worsening symptoms.
Schwartz GS, Holland EJ (Univ. of Minnesota, Minneapolis, Associated Eye Care, Stillwater, Minn)
Oral Acyclovir for the Management of Herpes Simplex Virus Keratitis in Children
Ophthalmology 107: 278-282, 2000
This study included 7 children treated with oral acyclovir for Herpes Simplex virus (HSV) Keratitis for over a 10-yr period. In addition to oral acyclovir, 6 patients received topical antiviral medications. Two patients less than 1 yr age received 2 weeks of IV acyclovir prior to starting oral medication (because of high risk of disseminated disease).
The HSV Keratitis resolved within 10 days in all 7 patients. None had any loss of visual acuity. Oral acyclovir was well tolerated without adverse reactions.
The authors state that oral acyclovir clears visual axis quickly, hence reducing the risk of amblyopia. Oral acyclovir may be used for children to prevent active infectious epithelial keratitis, to prevent recurrences and to prevent infection in children receiving topical steroids for immune stromal keratitis.
Brodovsky SC, McCarty CA, Snibson G, et la (Univ of Melbourne, Australia)
Management of Alkali Burns: An 11-Year Retrospective Review
Ophthalmology 107: 1829-1835, 2000
This is one of the largest series reported, regarding treatment of alkali burns.
Records of 121 patients (admitted to a tertiary care center) from 1987 to 1998 were reviewed for :
a) time to corneal re-epithelialization,
b) final best corrected visual acuity
c) time to visual acuity
d) length of hospital stay
Complications include: limbal stem cell insufficiency and associated dry eye, persistent epithelial defects, infectious keratitis, stromalysis and perforation.
The prognosis is usually poor because of the saponification of cell membranes.
The authors divided corneal burns into 4 categories from mild to severe. They found that routine administration and intensive therapy with ascorbate and citrate are NOT required for patients with grade 1 or 2 mg.
The standard protocol (intensive topical steroids, ascorbate, citrate and antibiotics) tended to improve outcome for patients with grade 3 burns but had no effect on outcome for grade 4 burns.
Korb DR, (Korb Associates, Boston)
Survey of Preferred Tests for Diagnosis of the Tear Film and Dry Eye
Cornea 19: 483-486, 2000
36 optometrists and 41 ophthalmologists were sent a survey regarding diagnostic choices for assessment of tear film and dry eye.
There were responses from 34 optometrists and 34 ophthalmologists. Neither group identified any single test as their dominant first choice. The majority of respondents included the Schirmer test as one of their choices, yet few made it their first choice.
The choices listed reflect the diagnostic criteria of symptoms, interpalpebral surface damage, tear instability and tear hyperosmolarity.
Tsai RJ-F, Li L-M, Chen J-K (Chang Gung Univ, Taoyuan, Taiwan)
Reconstruction of Damaged Corneas by Transplantation of Autologous Limbal Epithelial Cells.
N Engl J Med 343: 86-93, 2000
The integrity of the normal ocular surface is maintained by
(1) Corneal, limbal and conjunctival cells
(2) Stable preocular films.
Limbal epithelial cells may be lost as a result of severe damage from :
a) chemical or thermal burns,
b) Stevens – Johnson Syndrome,
c) ocular cicatricial pemphigoid,
d) contact lenses,
e) severe microbial infection,
f) multiple surgical procedures,
Manifestations of limbal cell deficiency are
a) Corneal vascularization
b) Chronic inflammation of the cornea
c) Ingrowth of fibrous tissue
d) Corneal opacification
The authors postulate that transplantation of limbal epithelial cells of the contralateral cornea can be effective in restoring useful vision.
Transplantation of autologous limbal epithelial cells cultured on amniotic membrane was evaluated in 6 patients. Together with the sheet of limbal epithelial cells, the amniotic membrane was transplanted to the denuded corneal surface of the damaged eye after superficial keratectomy. There was finally rapid resurfacing in 2 to 4 days in all 6 eyes and visual acuity improved in 5 eyes.
There were no incidents of recurrent neo-vascularization or inflammation in the transplanted area (follow-up of 15 ± 2 months).
Stevenson D, and The Cyclosporin A Phase 2 Study Group (Mercy Hosp Professional Bldg, New Orleans, La; et al)
Efficacy and Safety of Cyclosporin A Ophthalmic Emulsion in the Treatment of Moderate-to-Severe Dry Eye Disease: A Dose-Ranging, Randomized Trial.
Ophthalmology 107: 967-974, 2000
Recent, population-based surveys have reported millions of people throughout the world affected by Kerato Conjunctivitis Sicca (KCS) or dry eye disease. As many as 17 to 25% of patients report symptoms of KCS.
Patients with uncontrolled KCS are more susceptible to endophthalmitis resulting from ocular infections. Chronic KCS results from an underlying cytokine and receptor mediated inflammatory process, which affects the lacrimal gland acini and ducts.
This leads to abnormalities in the tear film and disruption of the homeostasis of the ocular surface.
Topical treatment with cyclosporin A (0.05 to 0.1%) has been shown to reduce cell-mediated inflammatory responses in inflammatory ocular surface diseases.
In a study of 162 patients, 129 patients received cyclosporin A emulsion in various concentrations ranging from 0.05 to 0.4%, while 33 patients received vehicle only. A post treatment observation period of 4 weeks revealed that cyclosporin A emulsions were safe and effective (maximally 0.05 and 0.1%) in improving ocular manifestations of KCS.
Y Mashima, M Kawai, M Yamada (Dept. of Ophth, Keio Univ, Sch. Of Med. Tokyo, Japan).
Corneal electrolysis for recurrence of corneal stromal dystrophy after keratoplasty.
BJO, March 2002, 86(3), pg.273-75
The authors evaluated corneal electrolysis as a treatment for recurrent diffuse corneal opacities at the host graft interface of the corneal stroma or at the subepithelial region in two types of granular corneal dystrophy (GCD).
At surgery, the deep aspect of the graft was partially separated from host tissue to expose the deposits, leaving one third of the host graft junction intact. After everting the graft, electrolysis was applied directly to both surfaces of the host and the graft. Lamellar keratoplasty (LKP) or penetrating keratoplasty (PKP) are done for the treatment of GCD, Avellino corneal dystrophy (ACD) and the superficial variant of GCD. Phototherapeutic keratectomy (PTK) is currently used as a first line therapy in all 3 types.
However, recurrences of these dystrophies within the graft occur after several years following keratoplasty or PTK. As these recurrences are superficial, they are amenable to electrolytic removal.
The main advantage of corneal electrolysis before repeating PTK, is that it does not reduce corneal thickness.
K Hiti, J Walochnik, et al (Dept. of Ophth, Univ.of Graz, Austria)
Viability of Acanthamoeba after exposure to a multipurpose disinfecting contact lens solution and two hydrogen peroxide systems.
BJO, February 2002, 86(2), 144-146
Contact lens wear is the most prevalent risk factor for acanthamoeba keratitis.
This study tested the anti-acanthamoeba activity of 3 different contact lens storage solutions. Effects on trophozoites and cysts of three different Acanthamoeba species: A castellani, A hatchetti and A lenticulata, were tested.
It was found that the two step peroxide system: Titmus H2O2 is a very effective disinfectant contact lens solution, to avoid possible acanthamoeba infection of the eye.
H. Eleftheriadis, M Cheong, S Sandeman et al (Sussex Eye Hospital, Brighton UK)
Corneal Toxicity Secondary to inadvertent use of benzalkonium chloride preserved viscoelastic material in cataract surgery.
BJO March 2002, 86: 299-305
The long-term toxic effects of intraocular benzalkonium chloride (BAC) were studied in 19 operated patients, exposed to intraocular BAC preserved viscoelastic during cataract surgery.
The authors conclude that BAC is toxic to the corneal endothelium when used intraocularly, resulting in severe striate keratopathy. Though keratopathy clears in most cases, it leaves varying degrees of residual stromal thickening in all eyes. If penetrating keratoplasty is required, the results are excellent.
H Kaz Soong, Q Farjo, R F Meyer, A Sugar (Kellog Eye Centre, Univ of Michigan, Medical School)
Diamond burr superficial keratectomy for recurrent corneal erosion.
BJO, March 2002, 86(3), pg. 296-298
The authors reviewed 54 eyes (retrospectively) with recurrent corneal erosions, treated with diamond burr superficial keratectomy (DBSK).
DBSK was found to be effective and safe and a good alternative therapy to (1) needle stromal micropuncture, (ii) ND-Yag induced epithelial adhesion and (iii) Excimer laser surface ablation.
H.S. Dua, A J King, Annie Joseph (Univ. Hospital, Queen’s Medical Centre, Nottingham, UK)
A new classification of ocular surface burns.
BJO, 2001; 85: 1379-1383
Thermal and chemical burns represent potentially blinding ocular injuries.
Thermal burns results from (i) firework explosions (ii) steam (iii) boiling water (iv) molten metal (commonly aluminium).
Chemical burns may be from alkaline or acidic agents. Alkaline agents include (i)Ammonium hydroxide (fertilizer production) (ii) Sodium hydroxide (for cleaning drains and pipes) and (iii) calcium hydroxide (found in lime plaster and cement).
Alkaline agents have both hydrophilic and lipophilic properties and hence rapidly penetrate cell membranes and enter the anterior chamber.
The hydroxyl ion causes saponification of cell membranes, cell death and disruption of the extracellular matrix.
Acidic agents causing injury are sulphuric acid found in car batteries, sulphurous acid found in some bleaches, and hydrochloric acid (swimming pools).
Recovery of ocular surface burns depends upon :
(i) causative agent
(ii) Extent of damage to (a) corneal, (b) limbal and (c) conjunctival tissues at the time of injury.
Understanding and clinical application of the concept of limbal stem cells of the corneal epithelium and forniceal stem cells of the conjunctival epithelium has significantly improved the outcome of treatment.
Limbal based epithelial stem cells provide a steady supply of daughter cells which maintain a constant epithelial cell mass during normal epithelial cell turnover and during epithelial wound healing.
Conjunctival stem cells are located in the forniceal region and migrate away from the fornices to cover bulbar and tarsal conjunctiva.
New developments in the management of severe ocular surface burns include (i)autolimbal transplantation or (ii) allolimbal transplantation with or without amniotic membrane graft.
This is combined with systemic immuno suppression and topical instillation of autologous serum.
The authors have evolved a new classification ranging from grade I (very good) to grade VI (very poor prognosis), based on the following parameters.
(a) Clock-hours of limbal involvement
(b) Percentage of conjunctival involvement.
The presence of any surviving conjunctival epithelium, is a favourable prognostic indicator (when compared with eyes with total loss of corneal, limbal and conjunctival epithelium).
The authors stress the important concept of conjunctivalisation of the cornea which protects against progressive melting and perforation. The ensuing vascularisation promotes healing and facilitates repair, which provides an opportunity to perform restorative procedures later.
The new classification is based on the authors’ experience of 67 cases of ocular surface burns managed over several years (35 retrospective and 32 prospective).
In Grade II of this new classification (when < 3 clock hours of limbus are involved and < 30% adjacent conjunctiva is involved) a good prognosis may be expected with medical management.
(i)copious irrigation soon after injury
(ii) topical vitamin C drops,
(iii) topical citrate drops
(iv) Acetylcysteine drops.
(v) Judicious steroids and
As long as there is even one clock hour of limbal epithelium surviving, there is a chance to re-establish corneal epithelial cover, over at least the visual axis.
When attributing a grade, the extent of the limbal involvement takes precedence over the extent of conjunctival involvement.
M.C. Nishiwaki-Dantas, P E Correa Dantas et al (Ocular Emergency Service, Sao Paulo, Brazil).
Ipsilateral limbal translocation for treatment of partial limbal deficiency secondary to ocular alkali burn.
BJO, 2001; 85: 1031-1033
Alkali burns may result in damage to limbal stem cells which are fundamental in maintaining ocular surface integrity.
Manifestations of limbal deficiency are:
(i) Abnormal conjunctival-corneal healing with peripheral neovascularisation.
(ii) Chronic epithelial defect
(iii) Severe stromal inflammation.
Penetrating keratoplasty has a poor prognosis in these cases.
Ipsilateral limbal autografts were performed in 5 patients with partial limbal deficiency secondary to alkali burn.
All cases had regression of limbal deficiency. Visual acuity improved to a minimum of 20/60 to 20/20 without complications during follow-up ranging from 7 to 11 months.
A.C. Sobottka Ventura, M Bohnke ((Universitat Bern, Switzerland)
Pentoxifylline influences the autocrine function of organ cultured donor corneas and enhances endothelial cell survival.
BJO, 2001; 85: 1110-1114
Pentoxifylline has recognised effects on immune functions, particularly on cytokine production.
The authors have previously demonstrated that spiking of organ culture media with endotoxin elicited enhancement in the release of IL-6 and IL-8 from corneal tissue and these events coincided with degenerative changes in endothelial cells and actual cell loss.
Traces of donor derived endotoxin are found in up to 50% of corneal organ cultures and may trigger inflammatory responses in the host.
Twelve fellow pairs of donor corneas were cultured for 20 days, with change of medium on day 10. One of each pair was incubated in the absence, while the other in the presence of pentoxifylline (25 mg/ml).
Media samples were withdrawn at regular intervals during the course of incubation and screened for cytokines IL-6,IL-8 and prostaglandin E2.
Endothelial cell morphology and numerical density were assessed on days zero, ten and twenty.
It was found that adding pentoxifylline to culture media definitely led to improvement in endothelial cell survival and after day 10 to suppression of IL-6 and IL-8 secretion by corneal tissue.
Jurgen Bednarz, Vladmir Doubilei, et al (Hamburg, Germany)
Effect of three different media on serum free culture of donor corneas and isolated human corneal endothelial cells.
BJO, 2001; 85: 1416-20
Two specific endothelial cell media (F99 and Endothelial -SFM) were compared with the routinely used medium MEM for their use in serum free cultivation of human corneal endothelial cells (HCEC) and donor cornea.
After incubation in endothelial-SFM even under serum free conditions, corneae were found to be of higher quality with respect to endothelial cell survival, cell membrane integrity and keratocyte density.
D. Bohringer, T. Reinhard, et al (Eye Hospital of Heinrich-Heine-University and LIONS Cornea Bank North Rhine, Westphalia, Dusseldorf, Germany)
Influencing Factors on Chronic Endothelial Cell Loss Characterised in a Homogeneous Group of Patients
BJO, Jan.2002, 86(1): 35-38
177 patients after first normal risk keratoplasties for keratoconus were selected from the database of the author’s clinic.
Among 71 of them, at least 4 central endothelial cell density values were documented. From these patients, only those 53 without any intraocular procedures, without glaucoma and without graft rejection were studied.
It was found that increased postmortem time (i.e. long death to eye excision time interval), advanced donor age and storage time in organ culture exerted a significant negative effect on chronic endothelial cells loss.
J Plskova, L Kuffova, et al (Univ of Aberdeen, UK)
Evaluation of Corneal Graft Rejection in a Mouse Model
BJO, Jan.2002, 86(1): 108-113
In experimental models (and even clinically) corneal graft rejection presents as opacification and is the result of endothelial cell dysfunction or loss.
Recovery from opacification CAN occur suggesting,
(a) new endothelial cells can regenerate.
(b) sufficient numbers of original cells can regain function if opacification was due to temporary dysfunction.
Previous experimental studies of allograft rejection plus some new data are reviewed to support mechanism (b) above.
Though corneal opacity or oedema is a measure of endothelial dysfunction, it does not necessarily imply that endothelium has been lost and that graft rejection has occurred.
Corneal opacity is probably the most reliable, clinical parameter of the alloimmune inflammatory response in the experimental model.
Opacification is reversible and endothelium can recover (from transient opacification of some allografts).