The Advanced Glaucoma Intervention Study (AGIS): 5. Encapsulated bleb after initial trabeculectomy.

PURPOSE: To compare the incidence of encapsulated bleb after trabeculectomy in eyes with and without previous argon laser trabeculoplasty and to assess other risk factors for encapsulated bleb development. METHODS: After medical treatment failure, eyes enrolled in the Advanced Glaucoma Intervention Study (AGIS) were randomly assigned to sequences of interventions starting with either argon laser trabeculoplasty or trabeculectomy. In the present study we compared the clinical course for 1 year after trabeculectomy in 119 eyes with failed argon laser trabeculoplasty with that of 379 eyes without previous argon laser trabeculoplasty. Data on bleb encapsulation were collected at the time that the encapsulation was diagnosed, and 3 and 6 months later. RESULTS: Of multiple factors examined in the AGIS data for the risk of developing encapsulated bleb, only male gender and high school graduation without further formal education were statistically significant. Encapsulation occurred in 18.5% of eyes with previous argon laser trabeculoplasty failure and 14.5% of eyes without previous argon laser trabeculoplasty (unadjusted relative risk, 1.27; 95% confidence limits = 0.81, 2.00; P = .23). After adjusting for age, gender, educational achievement, prescribed systemic beta-blockers, diabetes, visual field score, and years since glaucoma diagnosis, this difference remains statistically not significant. Four weeks after trabeculectomy, mean intraocular pressure was 7.5 mm Hg higher in eyes with (22.5 mm Hg) than without (15.0 mm Hg) encapsulated bleb; at 1 year after trabeculectomy and the resumption of medical therapy when needed, this excess was reduced to 1.4 mm Hg. CONCLUSIONS: This study, as did two previous studies, found male gender to be a risk factor for bleb encapsulation. Four studies, including the present study, have reported a higher rate of encapsulation in eyes with previous argon laser trabeculoplasty; in two of the studies, one of which was the present study, the rate was not statistically significantly higher; in the other two studies the rate was significantly higher. The 4-week postoperative mean intraocular pressure was higher in eyes with than without encapsulated bleb; with the resumption of medical treatment the two means converged after 1 year.

Subconjunctival versus intrascleral mitomycin-C in trabeculectomy.

BACKGROUND AND OBJECTIVE: A randomized prospective comparison of sub-Tenon's administration of mitomycin-C (MMC) with intrascleral administration of MMC in trabeculectomy was performed to determine whether intrascleral application is superior to the standard sub-Tenon's application. PATIENTS AND METHODS: Twenty-four eyes of 23 patients were randomized to treatment with MMC (0.27 mg/ml for 5 minutes). The route of administration was subconjunctival in group A and intrascleral in group B. Preoperative and postoperative visual acuity (VA), intraocular pressure (IOP), number of medications, and complications were compared between the two groups. RESULTS: There was no statistically significant difference between the two groups preoperatively regarding VA, IOP, and number of medications. Postoperatively, IOP and number of medications required had decreased significantly in both groups. A significantly larger number of postoperative procedures were required in group B to control IOP (group A = 3, group B = 14, P = .002). CONCLUSION: Both methods of MMC application significantly decreased the IOP and the number of medicines required to control IOP after trabeculectomy. The intrascleral use of MMC resulted in the need for more surgery postoperatively (P = .002).

Four-week safety and efficacy study of dorzolamide, a novel, active topical carbonic anhydrase inhibitor.

OBJECTIVE: To investigate the activity and local and systemic safety of the topical carbonic anhydrase inhibitor, dorzolamide hydrochloride. DESIGN: Four-week, double-masked, randomized, placebo-controlled, parallel, three-center study. SETTING: Referral centers. PATIENTS: Forty-eight patients with bilateral open angle glaucoma or ocular hypertension and intraocular pressure (IOP) greater than 22 mm Hg entered the study. Two of 28 patients receiving dorzolamide and two of 20 patients receiving placebo were withdrawn due to adverse experiences. INTERVENTION: Dorzolamide (2%) or placebo to each eye three times daily for 4 weeks. MAIN OUTCOME MEASURES: Diurnal IOP curves; ophthalmologic evaluations including corneal ultrasound pachymetry and endothelial cell count; and systemic evaluations including vital signs, blood chemistries, complete blood cell counts, urinalysis, electrocardiogram, and drug and carbonic anhydrase activity levels in red blood cells. RESULTS: Mean IOP at morning trough (8 AM) decreased from 27.1 mm Hg at baseline to 23.5 mm Hg on day 29 with dorzolamide (-13.3%) compared with a decrease from 27.1 mm Hg to 26.4 mm Hg with placebo (-2.3%). Peak activity occurred 2 hours after administration, with IOP decreasing from 26.8 mm Hg at baseline to 21.8 mm Hg on day 29 with dorzolamide (-18.4%) vs 26.1 mm Hg to 25.5 (-2.4%) with placebo. Mean corneal thickness was slightly increased for the dorzolamide-treated group compared with the placebo-treated group (0.009 mm vs 0.001 mm, respectively, P < .05) and changes in endothelial cell counts were similar (-24 cells/mm2 vs -27 cells/mm2, respectively, P > .25). Mean carbonic anhydrase isoenzyme II activity in red blood cells decreased to 21% of baseline in dorzolamide-treated patients. There were no clinically significant differences in ocular or laboratory parameters between the dorzolamide and placebo groups. CONCLUSIONS: Dorzolamide demonstrated significant IOP lowering activity over 4 weeks. It was well tolerated and there were no clinically significant changes in ocular or systemic safety parameters.

Blood dyscrasias and carbonic anhydrase inhibitors.

Two new cases of aplastic anemia possibly associated with Neptazane (methazolamide) are reported. Several previous authors, as well as the manufacturer of Diamox (acetazolamide) and Neptazane, have recommended routine blood counts for patients on carbonic anhydrase inhibitors. Four surveys are presented of current practices with regard to blood monitoring. These include authors of case reports, 40 academic ophthalmologists, 81 ophthalmologists in private practice, and 66 glaucoma specialists. The vast majority does not routinely monitor blood counts of patients on carbonic anhydrase inhibitors. The value of routine blood monitoring is questionable both because of (1) the idiosyncratic, non-dose-related mechanism of the dyscrasias and (2) the variability of the timing of their onset and development. Regular observation and questioning of patients for symptoms are thought to be preferable. The importance of a thorough history when assigning an etiology to a dyscrasia is noted.

Additive effect of epinephrine to timolol therapy in primary open angle glaucoma.

Previous studies have suggested that the effect on intraocular pressure resulting from the combined use of timolol and epinephrine might be different when they are administered hours rather than minutes apart. Fourteen patients were randomly assigned to one of two treatment sequences in which 1% epinephrine borate was added either five minutes or three hours after 0.5% timolol maleate. Combined therapy was continued for two weeks, after which epinephrine administration was stopped for a two-week washout period. The patient groups were then crossed over to the other dosage interval. There was an initial enhancement of pressure reduction when epinephrine was added to timolol in both sequences. After crossover, epinephrine was significantly additive to timolol in reducing pressure only when administered three hours after timolol. This additive effect was still present after three months of combined therapy.