Rebound of macular edema with continued use of methazolamide in patients with retinitis pigmentosa
G. A. Fishman, A. M. Glenn and L. D. Gilbert
Department of Ophthalmology and Visual Sciences, College of Medicine, University of Illinois at Chicago.
PURPOSE: To assess the effect of methazolamide on chronic macular edema in
patients with retinitis pigmentosa in a double-masked, placebo-controlled,
crossover study. Three subjects who had an initial improvement in their
macular edema as demonstrated on fluorescein angiography received a
continued course of methazolamide to assess its effect on macular 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 these continued
receiving the drug at a dosage of 50 mg twice daily for either an
additional 6 (one subject) or 12 (two subjects) weeks. All subjects were
assessed at each visit with fluorescein angiography and on best corrected
visual acuity, both undilated and dilated; a subjective impression was also
documented. RESULTS: After 6 and 12 weeks of treatment, all three subjects
experienced a rebound of angiographic macular edema to some extent. The
visual acuity varied only slightly (up to 7 letters) from both the baseline
and most recent examinations after 6 and 12 weeks of treatment. CONCLUSION:
Results from these few subjects suggest that at least a partial rebound of
macular edema seen angiographically may occur with the continued use of
methazolamide in patients with retinitis pigmentosa and chronic macular
edema. Further study is required to determine if this rebound effect also
occurs in treatment of other ocular disorders with chronic macular edema.
