To determine the prevalence of cystoid macular oedema (CME) by optical coherence tomography (OCT) in retinitis pigmentosa (RP) patients with no evidence of cystic macular lesions on fundus examination. We included 63 RP patients with no evidence of cystic-appearing macular changes on fundus examination. All patients underwent a complete ocular examination including best-corrected visual acuity using an ETDRS (Early Treatment Diabetic Retinopathy Study) chart, intraocular pressure measurement, anterior segment examination, and a detailed fundus examination. On 50 of the 63 patients, Fourier-domain OCT was performed using the radial slicer protocol. An additional 13 of the 63 patients were scanned using the macular thickness protocol on a time-domain OCT unit. The diagnosis of CME was defined by the presence of hyporeflective lacunae with well-defined boundaries on at least two of the scans. The mean age of patients included in the study was 36 years (range 9-71 years). Out of the 63 patients examined, 20 showed CME in at least one eye (32%), whereas 11 patients showed CME in both eyes (18%). Our findings demonstrate that a substantial number of RP patients with CME, as determined by OCT, may not show cystic changes by direct ophthalmoscopy or contact lens biomicroscopy. Knowledge of the high frequency for CME in such patients can serve to identify those who may be amenable to current or future treatment strategies of their macular oedema and can potentially impact on future therapeutic trials where visual acuity is used as an outcome measure.
