Which of the following is a listed cause of optic nerve atrophy?

• A. Glaucoma
• B. PRA
• C. Optic neuritis
• D. Trauma

Answer: (B)

Optic nerve atrophy can result from retinal degeneration that feeds the nerve, causing retrograde (trans-synaptic) degeneration of the optic nerve fibers. Progressive Retinal Atrophy is a retinal disease that progressively destroys photoreceptors and other retinal cells. As the retina deteriorates, the reduced or abnormal input to the optic nerve leads to structural and functional degeneration of the nerve itself, resulting in optic nerve pallor and thinning characteristic of atrophy.

Other options are direct insults to the optic nerve—glaucoma damages the nerve through chronic pressure and neuropathy, optic neuritis injures the nerve via inflammation, and trauma can directly disrupt the nerve fibers. The listed cause is included because retinal disease like PRA can indirectly produce optic nerve atrophy through this retrograde degeneration mechanism.