The prevalence of cystoid macular oedema in retinitis pigmentosa patients determined by optical coherence tomography

Aims: To determine the prevalence of cystoid macular oedema (CMO) in retinitis pigmentosa (RP) patients of various genetic subtypes using optical coherence tomography (OCT). Methods: We performed a complete ocular examination on 124 RP patients including best corrected visual acuity, intraocular pressure measurement, anterior segment and a detailed fundus exam. OCT images were then acquired using two different units. The presence of hypo-reflective lacunae was used to diagnose CMO. Results: Of the 124 patients, 47 showed CMO in at least one eye (38%), while 34 showed CMO in both eyes (27%). The prevalence of CMO in at least one eye for autosomal dominant (AD) patients was 52%, for autosomal recessive (AR) 39%, isolated 39%, Usher II 35% and none in the X linked recessive (XL) group. Using a chi-square analysis, no statistical significant difference was found for the prevalence of "bilateral CMO'' (p = 0.60) or "CMO in at least one eye'' (p = 0.59) among the AD, AR, isolated and Usher II genetic subtypes. Conclusion: Because of its notable prevalence, it would seem prudent to screen RP patients by OCT for the possible presence of CMO, to identify those amenable to treatment and also for future treatment trials when monitoring visual acuity.