Optical coherence tomography (OCT) features of cystoid spaces in choroideremia (CHM)

To investigate the prevalence and features of cystoid spaces (CS) in patients with confirmed genetic diagnosis of choroideremia (CHM) using swept source optical coherence tomography (OCT). We retrospectively reviewed CHM patients examined at the Regional Reference Center for Hereditary Retinal Degenerations at the Eye Clinic in Florence. We took into consideration genetically confirmed CHM patients with ophthalmological and swept source optical coherence tomography (OCT) examinations. The presence/absence and location of cystoid spaces in the retina of each eye were reported. A total of 42 eyes of 21 CHM patients were included in our series. The average age of the patients was 36.5 ± 20.1 (range, 13–73 years). The average best-corrected visual acuity (BCVA) for all patients was 0.63 ± 1.00 logMar (range, 0–2,80). CS were present in 15 eyes of eight patients (8/21, 38%). In all cases, CS were located in inner nuclear layer (INL); in five eyes of three patients, CS were detected also in ganglion cell layer (GCL). CS appeared as microcistoyd abnormalities and were detected in retinal areas characterized by retinal pigment epithelium (RPE) and outer retinal layers atrophy at the transition zone. Cystoid spaces in choroideremia showed peculiar features; they are clusters of small-size extrafoveal degenerative cysts mainly located in inner nuclear layer at the transition zone where outer retinal layers and RPE are severely damaged.