Gray Optic Disc Crescent: Evaluation of Anatomical Correlate by Spectral Domain Optical Coherence Tomography

Abstract Purpose To test the hypothesis that the anatomical correlate of the gray optic disc crescent is pigmentation of externally oblique border tissue of Elschnig. Design Observational cross-sectional study. Participants African American adult males with or without clinically apparent gray optic disc crescents. Methods McNemar's test for paired data and kappa statistic with 95% confidence intervals were used to examine the relationships between eyes with or without gray optic disc crescents and corresponding spectral domain-optical coherence tomography (SD-OCT) images with Enhanced Depth Imaging (EDI). Main Outcome Measures Correlation between clinical gray optic disc crescents and hyperreflectivity of externally oblique border tissue of Elschnig by SD-OCT with EDI. Results Twenty-five eyes had clinically apparent gray optic disc crescents, of which SD-OCT with EDI revealed hyperreflectivity (interpreted as increased pigmentation) of externally oblique (obtuse angle) border tissue of Elschnig in 22 eyes, i.e., extending into Bruch's membrane opening and presumably visible by funduscopy. Thirty-two eyes from matched participants had no apparent gray optic disc crescent, of which SD-OCT with EDI revealed hyperreflectivity of the border tissue of Elschnig in 23 eyes, but with a non-oblique (right angle) or internal (acute angle) angle, which would presumably obstruct funduscopic visualization. Conclusions Observations by SD-OCT with EDI suggest that the anatomical correlate of the gray optic disc crescent is pigmentation of externally oblique border tissue of Elschnig.