Optic Disc Hypoplasia Assessment in PAX6-Related Aniridia

Abstract

Background: This study aims to characterize optic disc hypoplasia in congenital aniridia using ultra-wide-field imaging (UWFI) and nonmydriatic retinal photography (NMRP). We also investigated the relation between optic disc hypoplasia and foveal hypoplasia. Methods: This is a retrospective case series of patients diagnosed with PAX6-related aniridia in a National Referral Center, who underwent UWFI, NMRP, and spectral-domain optical coherence tomography (SD-OCT). The disc diameter (DD) and the disc-to-fovea distance (DF) were measured. The DD:DF ratio was used to assess the relative size of the optic disc. The analyses were carried with respect to paired age- and sex-matched healthy controls. SD-OCT was used for foveal hypoplasia grading (from 1 to 4) and retinal nerve fiber layer (RNFL) analysis. Results: Mean manual DD:DF ratio was 0.33 (95% CI: 0.31–0.35) in aniridia patients versus 0.37 (95% CI: 0.36–0.39) in control patients (n = 20, P = 0.005) measured on NMRP and 0.32 (95% CI: 0.30–0.35) in aniridia patients versus 0.37 (95% CI: 0.37–0.39) in control patients (n = 26, P < 0.0001) when assessed on UWFI. Mean semiautomated DD:DF ratio measured on UWFI in aniridia patients was 0.31 (95% CI: 0.29–0.33) versus 0.37 (95% CI: 0.36–0.38) in control patients (P < 0.0001). Also, a negative correlation was found significant between the grade of foveal hypoplasia and the mean semiautomated DD:DF ratio (r = −0.52, 95% CI: −0.76 to −0.15, P = 0.0067). Finally, a significant negative correlation was found between the peripapillary temporal RNFL thickness and the grade of foveal hypoplasia (P = 0.0034). Conclusions: The DD:DF ratio is significantly reduced in PAX6-related aniridia patients and correlates with the severity of foveal hypoplasia. This ratio is a valuable tool for optic disc hypoplasia assessment in congenital aniridia, especially when provided semiautomatically by UWFI.