Where is the optic nerve head located and what is histologically notable there?

• A. At the macula; high cone density.
• B. At the optic disc; absence of photoreceptors and convergence of ganglion cell axons; lamina cribrosa present.
• C. At the fovea; thick photoreceptor layer.
• D. At the optic disc; prominent photoreceptor layer and no lamina cribrosa.

Answer: (C)

The optic nerve head is the spot where retinal ganglion cell axons exit the retina to form the optic nerve, located at the optic disc. Histologically, this region is characterized by the absence of photoreceptors because the retina ends there and the neural elements converge to channel into the optic nerve. The axons gather into bundles and pass through the lamina cribrosa, a sieve-like structure in the sclera. This combination—no photoreceptors, convergence of ganglion cell axons, and the presence of lamina cribrosa—distinguishes the optic nerve head from other retinal regions. Regions like the macula or fovea are rich in photoreceptors (the fovea, in particular, has a thick photoreceptor layer) and are not the exit point for the optic nerve.