congenital scleral crescent

crescent, congenital scleral 

A white semilunar patch of sclera seen adjacent to the optic disc due to the fact that the choroid and retinal pigment epithelium do not extend to the optic disc. This condition is present at birth, unlike myopic crescent, and is often associated with defective vision and tilted disc or situs inversus of the disc. Syn. Fuch's coloboma (if located at the lower edge of the disc). See situs inversus disc; tilted disc.
Full browser ?