EFFECT OF ORAL CARBONIC ANHYDRASE INHIBITOR ON CYSTOID MACULAR EDEMA ASSOCIATED WITH RETINITIS PIGMENTOSA: An OCT and OCT Angiography Study

PURPOSE: To investigate the factors associated with visual improvement in response to oral carbonic anhydrase inhibitors (CAIs) and the occurrence of microvascular changes in patients with retinitis pigmentosa–associated cystoid macular edema (RP-CME). METHODS: This retrospective cohort study included 59 eyes from 39 patients with RP-CME who underwent at least 3 months of oral CAI treatment. The eyes were divided into responding and nonresponding groups based on optical coherence tomography (OCT) criteria (resolution of cyst and reduction of foveal or parafoveal volume). All eyes were assessed before and after treatment using OCT and OCT angiography. RESULTS: Thirty-three eyes (55.9%) demonstrated a positive response to treatment, and 26 eyes (44.1%) did not. Compared with nonresponding eyes, responding eyes had a significantly higher frequency of multilayer CME than CME limited to the inner nuclear layer (P = 0.016). Subgroup analysis within the responding group revealed that improvements in visual acuity were more likely in eyes with fovea-involving CME and a higher baseline external limiting membrane and ellipsoid zone width. Microvascular parameters showed no significant changes after treatment. CONCLUSION: Eyes with CME extending to the outer nuclear layer or central fovea, and higher initial photoreceptor integrity may be prognostic factors associated with structural and functional improvements after carbonic anhydrase inhibitors treatment. Early treatment of multilayer CME with foveal involvement seems to be crucial in preventing irreversible photoreceptor damage.