REBOUND OF MACULAR EDEMA WITH CONTINUED USE OF METHAZOLAMIDE IN PATIENTS WITH RETINITIS-PIGMENTOSA

Purpose: To assess the effect of methazolamide on chronic macular edem a in patients with retinitis pigmentosa in a double-masked, placebo-co ntrolled, crossover study. Three subjects who had an initial improveme nt in their macular edema as demonstrated on fluorescein angiography r eceived a continued course of methazolamide to assess its effect on ma cular edema. Methods: Seventeen subjects were enrolled in the initial study. On angiography, nine subjects demonstrated improvement in their macular edema with the use of methazolamide for 3 weeks; three of the se continued receiving the drug at a dosage of 50 mg twice daily for e ither an additional 6 (one subject) or 12 (two subjects) weeks. All su bjects were assessed at each visit with fluorescein angiog raphy and o n best corrected visual acuity, both undilated and dilated; a subjecti ve impression was also documented. Results: After 6 and 12 weeks of tr eatment, all three subjects experienced a rebound of angiographic macu lar edema to some extent. The visual acuity varied only slightly (up t o 7 letters) from both the baseline and most recent examinations after 6 and 12 weeks of treatment. Conclusion: Results from these few subje cts suggest that at least a partial rebound of macular edema seen angi ographically may occur with the continued use of methazolamide in pati ents with retinitis pigmentosa and chronic macular edema. Further stud y is required to determine if this rebound effect also occurs in treat ment of other ocular disorders with chronic macular edema.