Evaluation of optic nerve head configurations of superior segmental optic hypoplasia by spectral-domain optical coherence tomography.

Abstract

To characterise the optic nerve head (ONH) configurations of superior segmental optic hypoplasia (SSOH) using a spectral-domain optical coherence tomography (SD-OCT). Horizontal cross-sectional images of the ONH were obtained by a SD-OCT in 20 eyes of 14 patients with clinically typical SSOH and 20 age- and refraction-matched normal eyes. Extension of retinal pigment epithelium (RPE) over the disc margin was observed in 20 eyes (100%) with SSOH and eight (40%) control eyes (p<0.001). The maximum length of the overhanging RPE measured at the nasal disc margin was significantly longer in eyes with SSOH than in controls (295.9+/-112.6 vs 24.3+/-33.9 microm; p<0.0001). In eyes with SSOH, the retinal nerve fibre layer (RNFL) was significantly thinner in the temporal-superior to nasal sectors (p<0.01). The extension of RPE over the nasal disc margin was more common and longer in eyes with SSOH than in normal eyes, suggesting that the SD-OCT findings might facilitate the diagnosis of SSOH. Substantial thinning of the RNFL was present in wider areas than previously expected in SSOH.