Aim To evaluate the therapeutic effect of continuous treatment with topical dorzolamide (a carbonic anhydrase inhibitor) for cystoid macular oedema (CME) associated with retinitis pigmentosa (RP).

Methods 18 eyes in 10 patients with CME secondary to RP were included. Baseline visual acuity, visual field and optical coherence tomography (OCT) measurements were obtained for all patients. All patients used 1% dorzolamide three times daily in each affected eye. Patients underwent follow-up examinations at 1, 3, 6, 12 and 18 months after treatment. The response to treatment was monitored by the Humphrey field analyser (HFA: the central 10-2 program); in addition, foveal thickness was measured by OCT. Evaluation of ‘macular sensitivity’ was calculated by HFA as the average of 12 central points.

Results The ‘macular sensitivity’ in 10 eyes in which CME was almost completely resolved was significantly improved (p<0.05). In eight of the nine eyes in which CME was almost completely resolved within 6 months, the therapeutic efficacy persisted through 18 months. Five eyes which were almost completely resolved or showed an initial response within 6 months experienced recurrence of CME.

Conclusions The prolonged (longer than 1 year) use of topical dorzolamide is effective for the treatment of CME in patients with RP. Therefore, we propose topical dorzolamide treatment as a first choice.