All cells have surface membranes, and this membrane is especially important in the light-sensitive cells of the eyes in your body. Within your eyes are millions of photoreceptors – nerve cells that capture light to form images of the world around you. The surface membranes of these nerve cells are packed with rhodopsin, a protein that detects light. These are the light-sensing membranes of the eyes that absorb packets of light to trigger nerves causing the sensation of sight.