Efficacy and prognostic factors of response to carbonic anhydrase inhibitors in management of cystoid macular edema in retinitis pigmentosa

Abstract

Purpose: To determine the efficacy and prognostic factors associated with carbonic anhydrase inhibitors (CAI) in the treatment of cystoid macular edema (CME) in retinitis pigmentosa (RP).

Methods: This was a cohort study of 81 subjects who were assessed before and after treatment. Spectral-domain optical coherence tomography (SD-OCT) was used to quantify CME. A reduction of at least 11% in central subfield (CSF) thickness was defined as objective evidence of response.

Results: In the 125 eyes that received topical dorzolamide, 40.0% demonstrated a response to treatment with a mean reduction in OCT CSF thickness of 105 μm (95% confidence interval [CI]: 82, 128). Mean starting visual acuity (VA) increased from 6/15 to 6/12 after a median time on treatment of 3.0 months. In patients prescribed oral acetazolamide, 28.1% of eyes (41.2% of patients) showed improvement in mean OCT CSF thickness of 115 μm (95% CI: 52, 177) over a median treatment interval of 4.0 months. Visual acuity improved from 6/15 to 6/12. Eyes that responded to topical dorzolamide were more likely to have autosomal recessive than autosomal dominant RP (44.6% vs. 23.3%, P = 0.02), and a higher mean baseline OCT CSF than eyes that did not respond (P = 0.02).

Conclusions: We report that 40.0% of eyes (53.1% of patients) showed an objective improvement in CME after treatment with topical dorzolamide and 28.1% of eyes (41.2% of patients) after treatment with oral acetazolamide. Autosomal recessive RP and greater initial central retinal thickness predicted response to treatment with topical dorzolamide.

Keywords: acetazolamide; cystoid macular edema; dorzolamide; retinitis pigmentosa.