Researchers have identified new details about the role of vitamin A in enabling the eye to sense light. The discovery could inform the hunt for new therapies for a number of visual impairments.

When light hits photosensitive pigments called opsins in the retina, a chemical called 11-cis retinal, derived from vitamin A, is converted into the molecule all-trans retinol. This triggers chemical reactions that generate the electrical signals that form the basis of vision in the brain.

The retinal pigment epithelium (RPE) drives the reversal of this process to restore the sensitivity of opsins to light, enabling the visual cycle to begin again. A protein called RPE65 plays a key role by binding to RPE cells.