Reduction in corneal haze and apoptosis by amniotic membrane matrix in excimer laser photoablation in rabbits.

PURPOSE: To determine whether preserved human amniotic membrane can reduce corneal haze and keratocyte apoptosis induced by excimer laser photoablation in rabbit corneas. METHODS: Excimer photoablation was performed bilaterally in 30 rabbits with a 6.0 mm ablation zone and 120 microm depth using the VISX Star laser with the phototherapeutic keratectomy (PTK) mode. One eye was randomly covered by preserved human amniotic membrane secured with 4 interrupted 10-0 nylon sutures, and the other eye served as the control. The amniotic membranes were removed at 1 week, and corneal haze was graded with slitlamp biomicroscopy by 3 masked corneal specialists biweekly for the ensuing 12 weeks until the rabbits were killed. Another 18 rabbits were divided into 4 subgroups and received PTK alone, PTK with membrane, PTK with sham sutures, or PTK with tarsorrhaphy. All eyes were studied histologically, and 3 eyes in each group were studied by in situ terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling assay at 1, 3, and 7 days and 12 weeks, respectively. RESULTS: A consistent grading of differences in corneal haze scoring between the control corneas and the amniotic-membrane-covered corneas was noted among the 3 masked observers. Organized reticular post-PTK corneal haze peaked at 7 weeks in both groups, and the corneal haze score in the amniotic-membrane-covered group was significantly less than in the control group from 7 to 12 weeks (all P < .001). Compared to the control corneas, the amniotic-membrane-covered corneas had less inflammatory response at 1 and 3 days, less keratocyte apoptosis in the ablated anterior corneal stroma at 1, 3, and 7 days (P < .001), and less stromal fibroblast cellularity and epithelial hyperplasia at 12 weeks. CONCLUSIONS: Amniotic membrane matrix introduced at an early stage of the corneal wound healing process effectively reduced corneal haze induced by excimer laser photoablation in rabbits. Studies linking suppression of apoptosis in the acute wound-healing process with reduction of subsequent corneal scarring may have useful clinical applications.

Acanthamoeba keratitis in New Zealand, including two cases with in vivo resistance to polyhexamethylene biguanide.

BACKGROUND: Acanthamoeba keratitis is an uncommon corneal infection that can run a protracted course with, at times, serious visual results. Eighty-five per cent of cases occur in soft contact lens wearers. The first New Zealand case occurred in 1990 and only seven cases have been identified in New Zealand to the end of 1996. METHODS: We surveyed the ophthalmologists looking after these seven cases of acanthamoeba keratitis as to time to diagnosis, treatment and outcome. RESULTS: New Zealand has a low incidence of this disease. All cases were soft contact lens wearers with defective care in every instance. After an initial two late-diagnosed cases, the time to diagnosis for four of the five other cases has been within 2 weeks. Medical treatment has varied over this series, but since the introduction of the cationic antiseptics polyhexamethylene biguanide (PHMB) and chlorhexidine in 1992, the last five cases were all treated with PHMB. One case diagnosed within 2 weeks ran a devastating course, despite intensive PHMB, and a second case remained culture positive after 1 year of PHMB and the late addition of chlorhexidine. Debridement, 0.1% PHMB and hexamidine eventually settled this eye. CONCLUSIONS: For treatment PHMB, hexamidine rather than propamidine and surgical debridement are favoured. While all Acanthamoeba isolates show good in vitro sensitivity to PHMB, the in vivo response is not always proportionate. A bacterial endosymbiont may have been a factor in the favourable outcome of one protracted case.

A controlled clinical trial of dorzolamide: a single-centre subset of a multicentre study.

PURPOSE: To assess the safety and intraocular pressure (IOP)-lowering activity of 2% dorzolamide (topical carbonic anhydrase inhibitor), compared to 0.5% timolol and 0.5% betaxolol eyedrops. METHODS: A parallel, masked, randomised one-year clinical trial was conducted in 16 patients with open-angle glaucoma or ocular hypertension, being a subset of a multicentre study which enrolled 523 subjects. Patients had IOP > 22 mmHg in one eye at baseline following washout of ocular hypotensive medications and were then randomised in a 3:1:1 ratio to receive 2% dorzolamide thrice daily, 0.5% timolol twice daily or 0.5% betaxolol twice daily respectively. IOP was measured at Hour 2 (morning peak), Hour 5 and Hour 8 (afternoon trough for dorzolamide) at baseline, Weeks 2 and 4 and Months 2, 3, 6, 9 and 12. RESULTS: Topical dorzolamide 2% solution was well tolerated and safe. Mean IOP for dorzolamide at Hour 2 was 29.1 mmHg at baseline and 20.8 mmHg on treatment at one year, a 28.5% change. Mean IOP for dorzolamide at Hour 8 was 24.5 mmHg at baseline and 20.2 mmHg on treatment at one year, a 17.6% change. Comparable percent changes for timolol and betaxolol were 43.2/25.7 mmHg at Hour 2 and 21.9/13.5 mmHg at Hour 8 respectively. CONCLUSIONS: Dozolamide 2% given thrice daily was well tolerated and safe, with a clinically significant effect on IOP comparable to betaxolol 0.5% twice daily, but not as great as timolol 0.5% twice daily.

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.

Acanthamoeba keratitis: a sobering case and a promising new treatment.

This case report describing Acanthamoeba keratitis in a 41-year-old male disposable contact lens wearer, adds some sobering and some encouraging information for the future management of this infection. Initial treatment with topical propamidine isethionate (Brolene) and polymyxin B/neomycin/gramicidin (Neosporin) led to an unsatisfactory clinical response. Topical miconazole 1%, prednisolone acetate 0.12% and oral itraconazole were then added to his treatment. This was later discontinued on noticing ipsilateral toxic cataract formation and an unresponsive pupil. The above medications were replaced with topical polyhexamethylene biguanide (PHMB) 0.02%, which we had shown to have superior in-vitro amoebicidal activity when compared to the other antiamoebic agents used in this case. Withdrawal of the multitreatment schedule and commencement of PHMB was associated with resolution of his keratitis, healing of a large epithelial defect and settling of severe conjunctivitis. The identical Acanthamoeba strain was isolated from the patient's contact lens storage case and cornea, possibly implicating the contaminated contact lens case in the aetiology of his keratitis. This is the first Australasian experience using PHMB to treat Acanthamoeba keratitis. It appears to be a promising new treatment for this infection.

Fusidic acid prophylaxis before cataract surgery: patient self-administration.

In a placebo-controlled, randomised, double-blind clinical trial, the authors evaluated the efficacy of patient-administered 1% fusidic acid viscous eye drops in clearing the commonest organisms causing pseudophakic endophthalmitis (Staphylococcus epidermidis and aureus) from the lids and conjunctivae of 79 patients before cataract surgery. The treatment group self-administered fusidic acid viscous eye drops four times daily for seven days before surgery; the placebo group received inert ophthalmic drops. Fellow eyes of both groups remained untreated as a natural control. Lower fornix and lid margin cultures were taken from both eyes before and after treatment. Before treatment, there was no statistical difference in organism counts between the groups. After treatment, eyes receiving fusidic acid were more likely to be free of clinically relevant Staphylococcus spp. than all pre-treatment eyes (for lids, P << 0.001; conjunctivae, P = 0.02). A highly significant (P < 0.001) number of lid margins were rendered 'clinically clean' (i.e., 0-49 organisms/swab) by fusidic acid when compared with untreated eyes. Treatment also effectively (P < 0.05) reduced the numbers of bacteria isolated from conjunctivae. This study indicates that there is a highly significant reduction of Staphylococcus spp. (P << 0.001), non-Staphylococcus spp. (P << 0.001) and attainment of sterile eyes (P << 0.001) at operation gained by patient self-administration of 1% fusidic acid four times daily for seven days before surgery.

A similar ribosomal protein S6 kinase activity is found in insulin-treated 3T3-L1 cells and chick embryo fibroblasts transformed by Rous sarcoma virus.

Insulin and transformation by Rous sarcoma virus stimulate the phosphorylation of ribosomal protein S6. Soluble fractions containing activated S6 protein kinase from insulin-treated cells and from transformed chick embryo fibroblasts were compared. Based upon several characteristics notably elution from DEAE-cellulose and sedimentation in glycerol gradients, these two S6 protein kinase activities appear to be similar enzymes. Thus insulin and retroviral transformation may activate the same enzyme to regulate the phosphorylation state of S6.