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 (IVDI) and topical carbonic anhydrase inhibitors (CAI) in the treatment of retinitis pigmentosa (RP)-related cystoid macular edema (CME). Methods: Patients with bilateral RP-related CME were treated with IVDI in one eye and topical CAIs in the contralateral eye. The primary endpoint was a change in central macular thickness (CMT). Secondary endpoints were changes in BCVA and microperimetric central retinal sensitivity. IOP and other ocular complications were evaluated for safety assessment. Results: Nine patients were recruited for this 12-month follow-up study. CMT was significantly lower in IVDI- than in topical CAI-treated eyes at Months 1 and 7, while mean BCVA was better in eyes treated with topical CAIs 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 IVDI. IVDI showed an effect on the contralateral eye in 5/9 patients. Conclusion: IVDI was more effective than topical CAIs in reducing RP-related CME one month after treatment. Corticosteroids can play a key role in the management of RP-related CME, however their routes, timing and modes of administration should be further explored.