Description
Optic nerve head is an area of opening within the scleral canal; pigmentary changes at the margins and around the disc encompass a few important differential diagnoses. Optic nerve head grey crescent is one such clinical entity where it is characterised by bilateral greyish pigmentation of the temporal neuroretinal rims. The appearance is due to an internal extension of Bruch's layer into the peripapillary scleral canal. It was first noted by Shields in 1980 in African-American patients. The pigmentation mainly lies within the optic nerve head; in contrast, the alpha and beta zone lies outside the optic nerve head. The beta zone of peripapillary region is mainly an atrophy of the choroid and retinal layers for a varying degree with underlying visible sclera, whereas the crescent area is an area of encroachment of the peripapillary layers onto the disc. The clinical implication of this clinical entity is...
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