What happens to light that enters the eye?

• A. It is focused on the retina and stimulates the rod and cone receptors, with the signals transduced into electrical impulses.
• B. It is converted at the cornea into chemical energy.
• C. It travels directly to the optic nerve without processing.
• D. It is reflected back out of the eye.

Answer: (A)

Light entering the eye is first refracted by the cornea and further focused by the lens so that an image falls onto the retina. The retina’s rods and cones detect this light and trigger phototransduction, a chemical change that converts light into electrical impulses. Those impulses are transmitted through retinal neurons to the optic nerve, which carries the information to the brain for processing. This description captures the essential sequence: focusing on the retina, receptor stimulation, and electrical signal transduction.

The cornea doesn’t convert light into chemical energy; that happens in the photoreceptors via photochemical reactions. Light signals aren’t sent directly to the optic nerve without retinal processing, and light isn’t simply reflected back out as part of the normal vision process.