To investigate the characteristics of the gray optic disc crescent and associated factors.

We retrospectively reviewed stereo fundus photographs of 590 glaucoma patients and 273 non-glaucoma patients. An experienced investigator evaluated the presence or absence of the gray crescent (a crescent-shaped, slate-gray pigmentation on the periphery of the neuroretinal rim) which is entirely inside the scleral crescent. Correlations with age, gender, refractive error, disc diameters, and the presence of glaucoma or peripapillary atrophy were also analyzed.

Out of 863 patients, the gray crescent was observed in 166 patients and was found in 19.0% of glaucoma patients and 19.8% of non-glaucoma patients. The gray crescent was most often located temporally (30.1%) and most frequently occurred within only 1 quadrant (63.9%). The prevalence of the gray crescent was not correlated with refractive error ( p = 0.61) or the occurrence of glaucomatous optic neuropathy ( p = 0.25), but was significantly related to peripapillary atrophy ( p < 0.001) and the horizontal diameter of the optic disc ( p = 0.001).

The gray optic disc crescent is a common finding within a glaucomatous or non-glaucomatous eye and factors significantly related to occurrence of the gray crescent include peripapillary atrophy and the horizontal diameter of the optic disc. Patients with gray crescent require special attention when the optic disc is examined.