Which of the following describes a key function of the retinal pigment epithelium?

• A. Nourishes retinal visual cells
• B. Contributes to the optic nerve
• C. Produces tears
• D. Generates aqueous humor

Answer: (D)

The retinal pigment epithelium primarily supports photoreceptors by providing nutrients and maintaining their environment. It sits adjacent to the photoreceptor layer and helps keep them healthy, including recycling visual pigments in the visual cycle and phagocytosing shed outer segment discs, which is essential for photoreceptor renewal. It also helps form the blood-retina barrier and absorbs excess light to reduce stray reflections. Because nourishing retinal visual cells captures this critical supportive role, that description best fits what the RPE does. In contrast, tears come from lacrimal glands, aqueous humor is produced by the ciliary body, and the optic nerve is formed by retinal ganglion cell axons, not by the retinal pigment epithelium.