The nutrient source for the lens comes from aqueous humor. Which feature facilitates this nutrient delivery?

The nutrient source for the lens comes from aqueous humor. Which feature facilitates this nutrient delivery?

• A. Aqueous humor bathing the lens in the anterior chamber
• B. Direct diffusion from retinal vessels
• C. Nutrients from the vitreous being transported through the lens
• D. Nutrient exchange via the corneal endothelium

Answer: (A)

The main idea is that the lens is avascular and relies on diffusion from surrounding fluids for nutrients. Aqueous humor constantly bathes the lens in the anterior chamber (and around its posterior surface as it circulates), delivering small molecules like glucose and ions that diffuse through the lens capsule into the deeper lens fibers. This continuous aqueous flow, produced by the ciliary body and circulating through the anterior and posterior chambers, is the primary nutrient source for the lens. Why the other ideas don’t fit: nutrients from retinal vessels don’t reach the lens directly because the lens is separated from the retina and there is no vascular connection to supply it. Nutrients from the vitreous would have to diffuse across vitreous or lens tissues in a way that isn’t the normal route for nourishment. The corneal endothelium exchanges nutrients with the cornea, not the lens, so it isn’t the pathway that nourishes lens fibers.

The main idea is that the lens is avascular and relies on diffusion from surrounding fluids for nutrients. Aqueous humor constantly bathes the lens in the anterior chamber (and around its posterior surface as it circulates), delivering small molecules like glucose and ions that diffuse through the lens capsule into the deeper lens fibers. This continuous aqueous flow, produced by the ciliary body and circulating through the anterior and posterior chambers, is the primary nutrient source for the lens.

Why the other ideas don’t fit: nutrients from retinal vessels don’t reach the lens directly because the lens is separated from the retina and there is no vascular connection to supply it. Nutrients from the vitreous would have to diffuse across vitreous or lens tissues in a way that isn’t the normal route for nourishment. The corneal endothelium exchanges nutrients with the cornea, not the lens, so it isn’t the pathway that nourishes lens fibers.