GLOSSARY

The retina is the inner, neural layer of the back wall of the eye that contains the photoreceptors (rods and cones), converts light into nerve signals, and performs early processing of the image before sending it to the brain; developmentally, the retina is part of the brain.

Main Layers (Deep to Surface)

• Pigment epithelium: absorbs stray light, nourishes the receptors, and recycles visual pigment.
• Photoreceptors: rods and cones.
• Bipolar, horizontal, and amacrine cells: processing and integration (such as enhancing contrast).
• Ganglion cells: their axons form the optic nerve.

An Interesting Point

Light must pass through all the neural layers to reach the receptors, so the human retina is “inverted”.

Special Regions

• Macula and fovea: the centre of the retina, with only cones, giving the sharpest vision and colour vision.
• Optic disc: where the nerve leaves; the blind spot.