Topical intrastromal steroid during laser in situ keratomileusis to retard interface keratitis

PURPOSE

To evaluate the effect of an intraoperative topical intrastromal steroid on the incidence and severity of nonspecific diffuse intralamellar keratitis (NSDIK).

SETTING

T.L.C. The Laser Center, Brea, California, USA.

METHODS

This prospective study included 2 cohort groups, each consisting of 105 consecutive eyes treated with laser in situ keratomileusis (LASIK) for myopia and astigmatism. Group A received the standard LASIK medication protocol and Group B, an additional drop of prednisolone sodium phosphate 1% solution on the undersurface of the cap immediately after it was reflected, prior to initiating the laser treatment. After the laser treatment was completed, the flap was repositioned; 1 minute after the steroid application, the interface was irrigated. All patients were examined postoperatively and placed in 1 of 4 categories: no interface keratitis, grade 1 (mild), grade 2 (moderate with decreased vision), or grade 3 (severe with decreased vision).

RESULTS

The incidence of NSDIK in Group A was 17.1% (18 eyes); 14 eyes (78.0%) were grade 1 and 4 (22.0%), grade 2. The incidence in Group B was 6.7% (7 eyes); all eyes were grade 1. Topical intrastromal steroid application significantly reduced the incidence and severity of NSDIK (P < .01).

CONCLUSION

We propose that intraoperative intrastromal steroid application is a safe and effective way to reduce the incidence and severity of NSDIK.

Balanced orbital decompression for Graves' ophthalmopathy

OBJECTIVE/HYPOTHESIS

Surgical management of Graves' ophthalmopathy is an alternative to medical therapy with corticosteroids or external beam radiotherapy. Orbital decompression has commonly been performed via a transantral approach to the medial orbital wall and floor. Although an endoscopic approach to these walls has been described, a balanced approach (incorporating a lateral decompression by an ophthalmology team) is desirable.

STUDY DESIGN

Retrospective review.

METHODS

Endoscopic medial decompression and extended lateral decompression were accomplished in 18 orbits (11 patients); inferior decompression was performed in 11 of these. Five additional procedures were performed.

RESULTS

Exophthalmos improved by a mean of 4.6 mm. All patients who underwent decompression for vision loss had improved vision after surgery. Exposure keratitis improved in six of six orbits. Two of five patients undergoing orbital decompression for vision loss developed postoperative diplopia, which was successfully treated with strabismus surgery or prism glasses. There were no other significant complications.

CONCLUSIONS

The endoscopic approach to the medial orbital wall is an important component of balanced orbital decompression for patients with Graves' ophthalmopathy. Balancing the decompression and preserving the medial orbital strut between the ethmoid cavity and the orbital floor may minimize the risk of diplopia.

Inhibition of corneal inflammation by the topical use of Ras farnesyltransferase inhibitors: selective inhibition of macrophage localization

PURPOSE

Ras farnesyltransferase inhibitors are known to block the membrane translocalization of oncogenic Ras protein. They inhibit the cytoplasmic mitogen-activated protein kinase signaling cascade related to Ras protein. Thus far, Ras farnesyltransferase inhibitors have been exclusively regarded with the anticancer drugs. The object of this study was to elucidate the role of Ras farnesyltransferase inhibitors on the corneal opacity induced by an inflammatory stimulus.

METHODS

We used a cauterization-induced corneal inflammation model. The central corneas of BALB/c mice were cauterized with silver nitrate (1 mm in diameter). Ras farnesyltransferase inhibitors, either manumycin or gliotoxin eye drops (each drug dissolved in balanced salt solution [BSS] at concentrations of 1 mM), were topically delivered to the cauterized cornea every 8 hours; BSS eye drops were used as a control. Clinical signs such as corneal edema, opacity, and corneal neovascularization, which are major causes of visual disturbance, were then examined 96 hours after the cauterization. The corneal edema and opacity were clinically scored under a stereoscopic microscope. The corneal neovascularization was evaluated by the length of the blood vessels from the limbus and the sum of extension central angle of vascularized limbus. Furthermore, the corneas were examined histologically, and the phenotypes of the cornea-infiltrating cells were analyzed by flow cytometry.

RESULTS

The control corneas showed prominent edema, neovascularization, and opacity. Histologic analysis revealed corneal epithelial and endothelial cell loss and a large amount of inflammatory cell infiltration into the corneal stroma. Flow cytometric analysis revealed that most of the infiltrating cells were neutrophils and macrophages. In contrast, the degree of corneal edema, neovascularization, and opacity was significantly less in the manumycin- or gliotoxin-treated corneas than in the control corneas. Histologically, the manumycin- and gliotoxin-treated corneas showed minimum edema and good epithelialization. Flow cytometric analysis showed corneal infiltration of macrophages to be selectively and clearly inhibited. Neither manumycin nor gliotoxin produced any side effects in the noncauterized normal cornea either clinically or histologically.

CONCLUSIONS

Ras proteins play an important role in cauterization-induced corneal inflammation and the opacity it induces. Ras farnesyltransferase inhibitors thus have a great potential for improving the treatment of corneal opacity induced by a corneal inflammatory stimulus.

Hydroa vacciniforme with ocular involvement

A 7-year-old Thai boy had several episodes of hydroa vacciniforme which were accompanied by an anterior uveitis with corneal clouding and stellate keratic precipitates. Wearing sunglasses prevented additional eye symptoms despite recurrence of the skin lesions. Repetitive UVA phototesting reproduced the typical skin lesions with fever and malaise. No reproduction of skin lesions was revealed by repetitive UVB phototesting. One should be aware of eye involvement in hydroa vacciniforme, and those who experience the eye involvement should be advised to wear protective sunglasses.

Lecithin-bound superoxide dismutase in the prevention of neutrophil-induced damage of corneal tissue

PURPOSE

To evaluate the effects of a lipophilic analog of superoxide dismutase (SOD) in the prevention of polymorphonuclear leukocyte (PMN)-induced damage to corneal epithelial cells in vitro and in bacterial corneal ulcers in vivo.

METHODS

Immortalized human corneal epithelial cells (T-HCEC) were cocultured with human PMNs activated with N-formyl-methionyl-leucyl-phenylalanine for 18 hours, after which lactate dehydrogenase (LDH) activity of the supernatant was measured as a marker of cellular damage. The inhibitory effects of lecithin-bound SOD (PC-SOD) and unmodified SOD, as well as PMNs pretreated with anti-CD 18 monoclonal antibody, were compared with untreated control. The retention of each drug on the ocular surface of healthy volunteers was measured by flow cytometry using brush cytology samples. The protective effects of a 0.1% solution of PC-SOD on Pseudomonas aeruginosa corneal infection in guinea pigs were assessed by inflammatory grading scores and histology.

RESULTS

Both PC-SOD and SOD effectively suppressed PMN-induced LDH release in T-HCEC in a dose-dependent manner. LDH release was also attenuated when PMNs were pretreated with anti-CD 18 antibodies, suggesting that adhesion molecules were involved in the process. Brush cytology of conjunctival samples showed that PC-SOD was retained longer on the ocular surface compared with unmodified SOD. PC-SOD significantly prevented excessive tissue damage by infiltrating PMNs in P. aeruginosa corneal infection, whereas in control eyes, perforation of the cornea occurred by 6 days.

CONCLUSIONS

PC-SOD was effective in attenuating PMN-related tissue damage to corneal tissue both in vitro and in P. aeruginosa infection in guinea pigs.

Contact lens associated bacterial keratitis: past, present, and future

PURPOSE

This paper reviews the medical history of the pathogenesis of contact lens related bacterial keratitis and its relationship to the development of successive generations of soft contact lenses.

METHODS

The Methods section presents a literature review and the author's personal experience.

RESULTS

Bacterial corneal infections have been a significant complication limiting the overall success of soft contact lenses for visual correction. Experience with different types of lenses has pointed to specific causes for the frequency of infection. However, there has been a general understanding that the health of the patient's epithelium, the patient's lens care practices, and the hypoxic effects of overnight wear each significantly contribute to the development of corneal infection.

CONCLUSIONS

A complete understanding of the pathogenesis of contact lens associated bacterial infection would allow the development of strategies to prevent infectious complications of lens wear. Progress appears to have been made with a trend toward fewer and less severe infections. As the possibility of a reasonably priced daily wear disposable lens with better oxygen transmissibility and surface modifications to limit deposits and bacterial adherence evolves, safer lenses will continue to be developed.

Bacterial keratitis in the critically ill

BACKGROUND

In the 4 year period (1988-91 there were nine cases of bacterial keratitis in five critically ill patients on an intensive care unit ('unit A'), all except one due to Pseudomonas aeruginosa. Many of these patients had serious ocular complications requiring surgery and all surviving patients were left with significant visual deficits. One further case of keratitis due to P aeruginosa occurred on unit A in April 1993. The problem of keratitis in ventilated patients is not unique to this unit as a further four cases in three patients from additional units in this area have been treated.

METHODS

Predisposing factors in unit A were established through subsequent investigations. It was found, in particular, that all the ocular infections were preceded by colonisation of the respiratory tract with the pathogenic organism. Recommendations concerning eye care and tracheal suctioning were adopted by unit A in 1991.

RESULTS

In the subsequent 4 years (1991-5), the frequency of isolation of pseudomonas from the respiratory tract per patient treated in unit A remained relatively high at 3.8% (153/4032). However, the conjunctival pseudomonas isolation rate has decreased significantly (p < 0.001) from 0.8% (19/2430) to 0.05% (2/4032).

CONCLUSIONS

Ventilated patients may be at risk from inoculation of pathogens into the eyes. The principal risk factor for bacterial keratitis in this series was corneal exposure secondary to conjunctival chemosis or lid damage. The adoption of simple preventative measures on unit A had a significant impact on the incidence of eye infections due to pseudomonas, despite the high proportion of patients whose respiratory tracts were colonised with the same organism. There is a need for additional research into the most effective method of eye care for ventilated patients in order to reduce the frequency of this avoidable condition.

Contact lens care using chlorhexidine acetate with ethyl-6-O-decanoyl-glucoside: a comparative clinical and bacteriological study

PURPOSE

We compared Ethyl-6-O-decanoyl-glucoside 0.005% (EDG) combined with 0.00025% chlorhexidine acetate (EDGC) to a commercial polyaminpropylbiguanide (PAPB).

METHODS

Fifty-nine subjects wearing both ionic and non-ionic contact lenses for 8-16 hours daily used either EDGC or PAPB as a cleaning and disinfectant agent. Neither mechanical nor separate cleaning agents were employed. The study period was for 8 weeks. The following symptoms were compared for each solution: blurred vision, dryness, foreign body sensation, redness, and dirty lenses. The following signs were also compared for each solution: conjunctival hyperemia, papillary hypertrophy, corneal deposits, purulence, limbal vascularization, subepithelial scarring, visual acuity, bulbar hyperemia, and tear breakup time.

RESULTS

After 8 weeks, 52% of the subjects in the EDGC group showed no evidence of corneal or conjunctival abnormalities. In contrast, only 19% of the subjects in the PAPB group showed no abnormalities of the conjunctiva or cornea (P = 0.012). After 8 weeks, 25% of the EDGC group showed evidence of papillary hypertrophy, whereas 50% of the PAPB group showed similar findings (P = 0.007). In addition, after 8 weeks of wear, 21% of the subjects using EDGC had positive conjunctival cultures, whereas the rate of positive cultures in the PAPB group was 50% (P = 0.035). At the conclusion of the study, the protein contents of the lenses were 131 micrograms +/- 48 micrograms (N = 29) in the EDGC group and 185 micrograms +/- 65 micrograms (N = 26) in the PAPB group (P = 0.001).

CONCLUSION

Subjects using EDGC had fewer pathological findings than subjects using PAPB as their cleaning and disinfecting agent. The mechanism by which EDGC reduced the rate of papillary hypertrophy needs further investigation.

[Contact lenses. 2: Contact lens associated infections]

Contact lens wearers, especially those who wear soft or extended wear contact lenses, are at increased risk of suffering from keratitis. Among the causes of corneal infections, an inadequate hygiene or overextended wear play an important role. An insufficient cleaning and disinfection leads to contamination with pathological germs. Sites of entry for these germs are corneal microlesions, caused by the setting and removal of contact lenses, and epithelial defects, as a result of the wearing of old or defective contact lenses. Primary eye diseases of patients who wear contact lenses can be altered by their wearing, and vice-versa. Even more, miscellaneous infections may lead to infectious corneal ulcerations. Having an adequate hygiene, a proper patient orientation during the medical visit, and a regular control are therefore of great importance for the reduction in the frequency of such infections by patients who wear contact lenses.

A controlled trial of oral acyclovir for the prevention of stromal keratitis or iritis in patients with herpes simplex virus epithelial keratitis. The Epithelial Keratitis Trial. The Herpetic Eye Disease Study Group

OBJECTIVE

To evaluate the efficacy of oral acyclovir in preventing stromal keratitis or iritis in patients with epithelial keratitis caused by herpes simplex virus (HSV).

METHODS

Patients with HSV epithelial keratitis of 1-week or less duration were treated with topical trifluridine and were randomly assigned to receive a 3-week course of oral acyclovir, 400 mg 5 times a day (hereafter referred to as the acyclovir group), or placebo (hereafter referred to as the placebo group). The development of HSV stromal keratitis or iritis was assessed during 12 months of follow-up.

RESULTS

Stromal keratitis or iritis developed in 17 (11%) of the 153 patients in the acyclovir group and in 14 (10%) of the 134 patients in the placebo group. Compared with the placebo group, the adjusted rate ratio for the development of stromal keratitis or iritis in the acyclovir group was 1.16 (95% confidence interval, 0.56-2.43). The development of stromal keratitis or iritis was more frequent in patients with a history of HSV stromal keratitis or iritis than in those without such a history (23% vs 9%; P = .01).

CONCLUSIONS

For patients with HSV epithelial keratitis treated with topical trifluridine, no apparent benefit of a 3-week course of oral acyclovir in preventing HSV stromal keratitis or iritis was seen during the subsequent year. The 1-year rate of development of stromal keratitis or iritis was lower than previously reported in the literature, except in patients with a history of HSV stromal keratitis or iritis.

Prophylactic and therapeutic efficacy of immunoglobulin G antibodies to Pseudomonas aeruginosa lipopolysaccharide against murine experimental corneal infection

PURPOSE

To evaluate the efficacy of lipopolysaccharide (LPS)-specific antibodies administered prophylactically or therapeutically to protect against corneal challenge with Pseudomonas aeruginosa.

METHODS

The prophylactic efficacy of active immunization with purified P. aeruginosa LPS was evaluated in a murine corneal-scratch model of P. aeruginosa keratitis. The same model was used to evaluate both the prophylactic and the therapeutic efficacy of systemic passive transfer of variable region-identical, isotype-switched, LPS-specific, murine immunoglobulin M (IgM) and immunoglobulin G (IgG) monoclonal antibodies (mAbs). The mAbs were injected intraperitoneally at various times either before or after corneal challenge and the corneal response was monitored macroscopically. In addition, immune rabbit sera were used to evaluate the efficacy of treatment.

RESULTS

Active immunization with homologous, but not heterologous, LPS before challenge reduced the severity of corneal disease and protected challenged mice against permanent corneal damage. Passive transfer of the LPS-specific IgM mAb 1F6 before challenge did not prevent corneal damage at any dose tested and had no effect on the course of disease. However, results of dose-response studies of the passive transfer of a variable region-identical IgG2b mAb, 2H3, before challenge indicated a 50% protective dose of 11.8 micrograms. When mAb 2H3 was administered at a dose of 50 micrograms before challenge and the challenge inoculum was increased, all mice were protected from corneal damage up to a challenge inoculum of 2.2 x 10(8) CFU/eye. When given 2 or 4 hours after corneal challenge with P. aeruginosa strain 6294 (which invades corneal epithelial cells during infection) but not when given at 8 or 24 hours, 50 micrograms of mAb 2H3 conferred significant protection (P < 0.05). The maximal interval after challenge during which this antibody could be administered and still protect 50% of mice was calculated by probit analysis to be 9.4 hours. Administration of homologous LPS-specific rabbit antiserum to mice at various times after challenge with P. aeruginosa strain 6206 (which is cytotoxic to corneal epithelial cells and does not remain in these cells during infection) resulted in significant protection when administered 4 or 8 hours after infection. Although probit analysis could not be performed with the available data, 50% of mice were completely protected when the antiserum was given up to 24 hours after challenge.

CONCLUSIONS

In an experimental model of P. aeruginosa keratitis, systematically delivered IgG antibodies directed against the O-side-chain antigens of P. aeruginosa, LPS conferred protection against severe corneal damage when administered both prophylactically and therapeutically.

[Contact lenses. Infections and hygiene]

BACKGROUND

Contact lens wearers are subject to increased risk of infection, and an attempt was made to determine which factors cause the overproportional risk of infection?

PATIENTS

The aim of this paper is to explain with appropriate bibliographic support why people who wear contact lenses are at risk of infection.

RESULTS

The relative risk of keratitis is a function of the lens material and the wearing time of the contact lenses. Extended wear of hydrogel lenses is associated with an overproportional risk of infection. According to the literature, the frequency of complications in contact lens wearers generally is the result of poor hygiene in 66% of the cases. The general lack of hygiene among contact lens wearers must, therefore, be regarded as one cause among pathophysiological mechanisms of the eye. The microbial spectrum favors gram-negative bacteria living in a wet environment such as Pseudomonas, Serratia and parasites like Acanthamoeba.

CONCLUSION

The specific spectrum of pathogens and new problem organisms not only challenge the fitter but also the manufacturers to adapt hygiene (sanitary) measures and products to the new development. Disposable contact lens systems are the first step, but they do not solve all the problems of contact lens wearers. Therefore, the importance of contact lens hygiene must be especially emphasized when the ophthalmologist is giving instructions to the patient. On the other hand, hygiene should also not be neglected by the contact lens fitters since it is part of the whole problem.

Heme oxygenase induction with attenuation of experimentally induced corneal inflammation

Heme oxygenase (HO), by catabolizing heme to bile pigments, down-regulates cellular levels of heme and hemeproteins; certain of the latter, i.e. cytochrome P450s, generate pro-inflammatory products from endogenous substrates. Two HO isozymes, the products of distinct genes, have been described; HO-1 is the inducible one, whereas HO-2 is believed to be constitutively expressed. We studied the inducing effects of several metal compounds [CoCl2, SnCl2, ZnCl2, heme, and cobalt protoporphyrin (CoPP)] on HO-1 mRNA content and enzyme activity in cultures of rabbit corneal epithelial (RCE) cells; these metal compounds are known to induce HO in other tissues. Additionally, we studied HO-1 expression in an experimental model of ocular inflammation produced in rabbit corneas by extended contact lens wear, and the relation of HO expression to the induced inflammatory process. SnCl2 added to RCE cells in vitro produced marked time- and concentration-dependent increases in HO-1 mRNA and HO-1 enzyme activity; CoCl2, ZnCl2, and CoPP were inducers of HO as well, though to a lesser degree than SnCl2. Corneas treated for 6 days with contact lenses impregnated with SnCl2 displayed substantially less corneal inflammation, swelling, and new vessel invasion than did controls; attenuation of ocular inflammation was paralleled by SnCl2-induced increases in HO mRNA and HO activity in corneal epithelial cells from treated eyes. It is suggested that amelioration of the inflammatory response produced by extended contact lens wear is due, in part, to the induction of high levels of HO-1 activity by SnCl2, which results in diminished production of pro-inflammatory mediators generated through heme-dependent metabolic processes. Regulation of HO activity in this manner may have clinical applications.

Secretory IgA inhibits Pseudomonas aeruginosa binding to cornea and protects against keratitis

PURPOSE

To determine whether secretory IgA (SIgA) antibody inhibits Pseudomonas aeruginosa binding to cornea in vitro and if boosting SIgA antibody in tears using heat-killed P. aeruginosa as an immunizing antigen is protective in vivo in experimentally induced bacterial keratitis in the mouse.

METHODS

SIgA, immunoglobulin-G, immunoglobulin-M, and an undiluted crude human milk preparation were tested in vitro for their ability to inhibit P. aeruginosa binding to the scarified corneas of adult (6 weeks to 6 months of age) mice by topical application of each before similar delivery of the bacterial inoculum. Scanning electron microscopy (scanning EM) was used to quantitate bacterial adherence. In vivo mice were immunized topically with heat-killed P. aeruginosa or sham immunized by application of a similar volume of phosphate-buffered saline (PBS). Tears were collected from both groups of mice and levels of immunoglobulins (Igs) measured by enzyme-linked immunosorbent assay (ELISA). After the second immunization, the same two groups were challenged ocularly with 5.0 x 10(7) colony forming units P. aeruginosa and the response to infection graded.

RESULTS

In vitro, after a 30-minute preincubation with Igs, SIgA (250 micrograms/ml) significantly decreased P. aeruginosa binding to cornea in vitro when compared to the number of bacteria bound in PBS control specimens, and binding reduction was concentration dependent. In vivo, 15 days after a second ocular topical immunization, tear SIgA was elevated significantly and was specific for P. aeruginosa when measured by ELISA. In vivo, corneal disease response grades in the heat-killed antigen immunized mice also were significantly less severe when compared to sham-immunized mice.

CONCLUSIONS

SIgA significantly inhibits binding of P. aeruginosa to the wounded mouse cornea in vitro, and inhibition is concentration dependent. In vivo, specific antipseudomonal SIgA in mouse tears can be elicited by topical ocular immunization with heat-killed P. aeruginosa, and a significant number of immunized animals with elevated levels of SIgA in their tears exhibited less severe ocular disease after bacterial challenge.

[Cornea protection in ptosis induced by botulinum injection]

Two patients, men aged 82 and 53 years, with weakness of the facial muscles after surgery in the posterior fossa had keratitis caused by the inability to blink and to close the eye. Botulinum toxin type A was injected into the levator palpebrae superioris muscle under electromyographic control. A selective, reversible paralysis of this muscle was induced without weakness of the anatomically related rectus superior muscle. This botulinum toxin-induced protective ptosis appeared to be effective and safe in the treatment and prevention of keratitis in patients with a temporary weakness of the facial muscles.

Moisture chamber versus lubrication for the prevention of corneal epithelial breakdown

BACKGROUND

Patients who are comatose or semicomatose are at risk of corneal dryness and ulceration.

OBJECTIVE

To compare and evaluate the effectiveness of two treatments used for the prevention of corneal epithelial breakdown in critically ill patients.

METHODS

A randomized clinical trial was used. The sample consisted of critically ill patients (age, 15-84 years) with a limited or absent blink reflex in a 14-bed general intensive care unit in a large metropolitan teaching hospital. Ninety-six eligible patients were studied; of these, 36 were excluded and data from the remaining 60 patients were analyzed. Patients were randomized to receive methylcellulose lubricating drops every 2 hours (n = 30) or to have their eyes covered with a polyethylene film to create a moisture chamber (n = 30). The patients' corneas were tested daily for epithelial breakdown using fluorescein drops. Patients were studied for a minimum of 48 hours and a maximum of 1 week.

RESULTS

Eight of the 30 patients in the lubricating drop group had positive fluorescein staining, compared with one in the moisture chamber group.

CONCLUSION

Our results suggest that a moisture chamber is more effective than lubricating drops in preventing corneal epithelial breakdown in critically ill patients with limited or absent blink reflex.

Irritation of the anterior segment of the eye by ultraviolet radiation: influence of nerve blockade and calcium antagonists

The aim of this investigation was to determine the influence on anterior segment inflammation elicited by UV radiation, of ocular denervation and pharmacological blockade of sensory nerve fibers with capsaicin, tetrodotoxin and calcium antagonists. Both eyes of pigmented rabbits were exposed for 5 min to UV radiation (254 nm); 24 h later, inflammatory signs were evaluated by biomicroscopy of the corneal epithelium, the stroma and the endothelium and scored from 0 to 4. Conjunctival vasodilation and miosis were also assessed. Two weeks before UV exposure, a group of rabbits received a retrobulbar injection of ethanol or of 1% capsaicin. Intact, capsaicin-treated and alcohol-denervated animals were treated topically, prior to UV exposure, with tetrodotoxin (0.78 mM) and the calcium antagonists diltiazem (1-28 mM) and nifedipine (10 mM). UV radiation produced at 24 h signs of corneal irritation, conjunctival hyperemia, miosis and elevated protein content of the aqueous humor. Retrobulbar injection of 99% alcohol or 1% capsaicin did not diminish significantly the inflammation of tissues directly exposed to UV radiation, although extension of inflammatory signs to unaffected areas was prevented. Pre-treatment of normal and denervated eyes with diltiazem attenuated UV-induced eye irritation signs at concentrations of 10 mM or over. The effect was less pronounced with tetrodotoxin and was not obtained with nifedipine. These findings suggest that the contribution of a neurogenic mechanism to anterior segment inflammation induced by UV exposure is modest. They also show that high concentrations of diltiazem, but not of nifedipine, effectively reduced inflammation of the anterior segment of the eye evoked by UV radiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninfectious inflammatory response to gold weight eyelid implants

We describe three patients with noninfectious inflammatory reactions to gold weight eyelid implants, a complication not previously reported. Eyelid edema and erythema developed gradually in each patient, and maximal inflammation that prompted treatment was present at 12, 3, and 5 weeks, respectively, after surgery in the three patients. Management involved removal of the implant in the first patient, oral corticosteroids followed by replacement of the implant by a platinum weight in the second patient, and a local corticosteroid injection with retention of the implant in the third. Histopathological features included a thick eosinophilic coagulum at the tissue-gold interface and an intense, predominantly lymphocytic infiltrate in the collagenous capsule that surrounded the implants. Gold weight eyelid implants can elicit a gradually progressive inflammatory response. In at least some cases, local corticosteroid injection may suppress the inflammation and permit retention of the implant.

Do Topical Corticosteroids Have a Role Following Excimer Laser Photorefractive Keratectomy?

The article reviews the evidence for and against the use of topical corticosteroids following PRK. Two significant problems after PRK are the development of corneal haze and unpredictability of the refractive outcome. These arise from changes in the anterior stroma, the deposition of new subepithelial tissue, and individual variations in the wound healing response. In rabbits, corticosteroids reduced corneal haze by limiting the synthesis of subepithelial collagen. However, in humans, controlled trials showed that corticosteroids had no lasting effect on either haze or regression, and were associated with an unacceptably high incidence of unwanted effects. The difference between species probably related to the relative absence of collagen and predominance of glycosaminoglycans during corneal wound healing in humans. Some human studies have shown rapid changes in refraction occurring within days of stopping or restarting corticosteroids. This suggests that their transient hyperopic effect is probably mediated by changes in the hydration of the tissue. Therefore, the role of corticosteroids in PRK is very limited. There is no justification for their routine use after PRK for low or moderate myopia. If corticosteroids have a role in improving haze or refractive outcome in selected patients, a means for their early identification must be found.

Acanthamoeba, bacterial, and fungal contamination of contact lens storage cases

BACKGROUND

Microbial corneal infection is the most serious complication of contact lens wear. Contact lens cases are a recognised potential source of pathogens associated with corneal ulcers.

METHODS

This survey established the incidence of protozoal, bacterial, and fungal contact lens case contamination in 101 asymptomatic daily wear cosmetic contact lens wearers from a domiciliary contact lens practice.

RESULTS

Eighty two (81%) contact lens cases were found to be contaminated, with 19 (19%) sterile. Of all contact lens cases, 78 (77%) grew bacteria, 24 (24%) fungi, and 20 (20%) protozoa. Acanthamoeba spp were isolated from eight (8%) contact lens cases. Fifty six (55%) contact lens cases yielded mixed bacterial contamination. This is the first contact lens case survey in which hydrogen peroxide disinfection was the major method of contact lens disinfection (75% of subjects) and no home made saline was used. All the contaminating organisms were shown to possess the enzyme catalase that breaks down hydrogen peroxide to oxygen and water. The polymicrobial nature of the biofilms found in many contact lens cases is illustrated electron micrographically.

CONCLUSION

Based on data from this and previous studies, the authors conclude with recommendations for contact lens wearers: (1) regular scrubbing of contact lens case interior to disrupt biofilms; (2) exposure of contact lens case to very hot water (> or = 70 degrees C) will kill Acanthamoeba contaminants; (3) allow contact lens case to air dry between uses; (4) if hydrogen peroxide disinfection is preferred, use a two step system; (5) replace contact lens case regularly.

A closed eye contact lens model of corneal inflammation. Part 2: Inhibition of cytochrome P450 arachidonic acid metabolism alleviates inflammatory sequelae

PURPOSE

The authors have previously shown a marked increase in corneal epithelial arachidonic acid metabolism to 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE) in a model of closed eye-contact lens wear. Their formation was predominantly cytochrome P450-dependent and significantly correlated with inflammatory score and corneal thickness. In the current study, the authors used stannous chloride to inhibit the epithelial cytochrome P450-dependent synthesis of 12-HETE and 12-HETrE to assess the role of these eicosanoids as mediators of the inflammatory response to contact lens wear in the closed eye.

METHODS

Hydrogel contact lenses were soaked in stannous chloride (100 micrograms/ml) or vehicle and fitted to the rabbit eye in stacked fashion (two lenses/eye), followed by a silk suture tarsorrhaphy of approximately 90%. Eyes were analyzed over a 7-day period for inflammatory responses through slit lamp biomicroscopy, subjective inflammatory scoring, ultrasonic pachymetry, and corneal epithelial [1-14C]-arachidonic acid metabolism.

RESULTS

Closed eye-hydrogel contact lens wear resulted in a progressive anterior surface inflammatory response. Coinciding with these events was a time-dependent increase in corneal thickness and 12-HETE and 12-HETrE production rates by corneal epithelial homogenates. Treatment of the lenses with stannous chloride (100 micrograms/ml) significantly attenuated by day 7 the inflammatory score (56% decrease), corneal thickness (17% decrease), and 12-HETE and 12-HETrE synthesis (77% and 71% decrease, respectively).

CONCLUSIONS

This study further substantiates the involvement of cytochrome P450, through the synthesis of 12-HETE and 12-HETrE, in the inflammatory response associated with hydrogel contact lens wear in the closed eye. Thus, inhibition of cytochrome P450, with subsequent decreases in 12-HETE and 12-HETrE, may attenuate the pathophysiologic response to contact lens wear in the closed eye.