Lamina cribrosa is absent in -: (A) Morning glory syndrome, (B) Nanophthalmia, (C) Colobama of retina, (D) Optic nerve agenesis
Answer is A. The nerve fibers forming the optic nerve exit the eye posteriorly through a hole in the sclera that is occupied by a mesh-like structure called the lamina cribrosa. It is formed by a multilayered network of collagen fibers that inse into the scleral canal wall. It is absent in morning glory syndrome. Ref khurana 6/e