Which statement about the RPE's role in the visual cycle is true?

• A. Vitamin A storage
• B. Produces vitreous
• C. Generates aqueous humor
• D. Photoreceptor synapses

Answer: (A)

Vitamin A storage in the retinal pigment epithelium is a key part of the visual cycle. The RPE acts as a reservoir for vitamin A, storing it as retinyl esters in retinosomes. This stored vitamin A supports the continuous regeneration of visual pigment: after phototransduction starts, all-trans retinol is transported to the RPE, converted through the visual-cycle enzymes (including RPE65) back to 11-cis retinal, and then shuttled back to photoreceptors to reform rhodopsin. This storage function ensures a readily available pool of vitamin A to sustain pigment regeneration, especially during dark adaptation. The other statements don’t reflect the RPE’s role: the vitreous is produced nearby during development and maintenance by other tissues, aqueous humor is produced by the ciliary processes, and photoreceptor synapses occur in the outer plexiform layer, not in the RPE.