Dexamethasone Implant Versus Topical Carbonic Anhydrase Inhibitors in Patients with Bilateral Retinitis Pigmentosa-Related Cystoid Macular Edema: A Prospective, Paired-Eye Pilot Study

Purpose: To compare within-subject efficacy and safety of intravitreal dexamethasone implant and topical carbonic anhydrase inhibitors in the treatment of retinitis pigmentosa-related cystoid macular edema. Methods: Patients with bilateral retinitis pigmentosa-related cystoid macular edema were treated with intravitreal dexamethasone implant in one eye and topical carbonic anhydrase inhibitors in the contralateral eye. The primary endpoint was a change in central macular thickness. Secondary endpoints were changes in best-corrected visual acuity and microperimetric central retinal sensitivity. Intraocular pressure and other ocular complications were evaluated for safety assessment. Results: Nine patients were recruited for this 12-month follow-up study. Central macular thickness was significantly lower in intravitreal dexamethasone implant-treated eyes than in topical carbonic anhydrase inhibitors-treated eyes at Months 1 and 7, whereas mean best-corrected visual acuity was better in eyes treated with topical carbonic anhydrase inhibitors at Month 12 (borderline significant P = 0.0510). There was no difference in microperimetric sensitivity between the two treatments. Three patients developed ocular hypertension after intravitreal dexamethasone implant. Intravitreal dexamethasone implant showed an effect on the contralateral eye in five of nine patients. Conclusion: Intravitreal dexamethasone implant was more effective than topical carbonic anhydrase inhibitors in reducing retinitis pigmentosa-related cystoid macular edema 1 month after treatment. Corticosteroids can play a key role in the management of retinitis pigmentosa-related cystoid macular edema; however, their routes, timing, and modes of administration should be further explored.