Outer retinal tubulation in retinal dystrophies

Background/Purpose: To evaluate the occurrence and characteristics of outer retinal tubulation (ORT) in an Indian population with retinal dystrophies. Methods: In this retrospective study, 309 eyes of 157 patients with retinal dystrophies including retinitis pigmentosa (RP, 183 eyes), Stargardt disease (STGD, 93 eyes) and Best disease (33 eyes) were reviewed. The demographic details, clinical data including visual acuity, treatment history and good quality spectral domain optical coherence tomography (SD-OCT) scans were collected. The characteristics of ORT including location, number, type, associated intraretinal fluid, disruption of outer retina and presence of other lesions were recorded. Results: ORT was detected in 12 eyes of 8 patients (unilateral in 4 eyes). Their mean age was 42.5 ± 13.89 yrs. (range, 21-60 yrs.), the mean baseline best corrected visual acuity was 0.425 ± 0.7 LogMAR (Snellen equivalent 20/53) and the median follow up was 6 months. The frequency of ORT were; 6 out of 183 (3%) eyes in RP, 2 out of 93 (2%) eyes in STGD, and 4 out of 33 (12%) eyes with Best disease and this difference in frequency was found to be statistically significant (χ² = 6.93, p = 0.03). The average number of ORT in each eye was 2.75 ± 2.0 and the mean height of ORT was 40.8 ± 15.4 mm. Three eyes had co-existing choroidal neovascularization. All eyes had tubular structures except one that had the branching type. The ORT in 2 eyes of one patient with Best disease who had 3 years follow up data was found to be stable over the entire period. Conclusion: ORTs are present in patients with RP, STGD and Best disease with a higher frequency in Best disease.