This refers to irreversible degeneration of the optic disc which develops remarkable pallor with reduction in number of capillaries below 7 against the normal 10 or more,
and the loss of substance of nerve head.
primary optic atrophy denotes occurrence of atrophy without previous opthalmoscopic evidence of papilledema/papillitis. It follows involvement of neurons proximal to the disk. Disk margins are well defined.
Secondary optic atrophy denotes occurrence of atrophy with previous evidence of papilledema/papillitis. It involves the choked disk. Disk margins are poorly defined.
Etiologic factors include intracranial tumors and traumatic, infalmmatory, vascular, and degenerative disorders. At times, progressive optic atrophy is hereditary.