Outer Segment

The part of the photoreceptor cell that is directly adjacent to RPE cells, near the back of the retina, and is responsible for the conversion of light into electrical signals, via the visual cycle.

One of the parts of a photoreceptor cell. Specifically, it is the last part of the photoreceptor that light passes through on its first pass (i.e.,before any reflections) through the retina. Outer segments are composed of stacked disks (think of a stack of pancakes) that are flattened in planes perpendicular to the path of the light. The proteins involved with the visual cycle are found in the outer segments and convert light into electrical energy transmitted to the optic nerve.