In optic atrophy pallor of the optic disc is an index of

OPTIC ATROPHY It refers to degeneration of the optic nerve, which occurs as an end result of any pathologic process that damages axons in the anterior visual system, i.e. from retinal ganglion cells to the lateral geniculate body. Clinical features of optic atrophy : 1. Loss of vision, may be of sudden or gradual onset (depending upon the cause of optic atrophy) and paial or total (depending upon the degree of atrophy). 2. Pupil is semi dilated and direct light reflex is very sluggish or absent. Swinging flash light test depicts Marcus Gunn pupil. 3. Visual field loss will vary with the distribution of the fibres that have been damaged. In general the field loss is peripheral in systemic infections, central in focal optic neuritis and eccentric when the nerve or tracts are compressed. ophthalmoscopic features of optic atrophy in general are: pallor of the disc and decrease in the number of small blood vessels (Kastenbaum index). The pallor is not due to atrophy of the nerve fibres but to loss of vasculature. Ref:- A K KHURANA; pg num:-301,302