Study clarifies process controlling night vision

New research reveals the key chemical process that corrects for potential visual errors in low-light conditions. Understanding this fundamental step could lead to new treatments for visual deficits, or might one day boost normal night vision to new levels.

Like the mirror of a telescope pointed toward the night sky, the eye’s rod cells capture the energy of photons - the individual particles that make up light. The interaction triggers a series of chemical signals that ultimately translate the photons into the light we see.

The key light receptor in rod cells is a protein called rhodopsin. Each rod cell has about 100 million rhodopsin receptors, and each one can detect a single photon at a time.

Scientists had thought that the strength of rhodopsin’s signal determines how well we see in dim light. But UC Davis scientists have found instead that a second step acts as a gatekeeper to correct for rhodopsin errors. The result is a more accurate reading of light under dim conditions.

A report on their research appears in the October issue of the journal Neuron in a study entitled “Calcium feedback to cGMP synthesis strongly attenuates single photon responses driven by long rhodopsin lifetimes.”