Retina

The retina does a job much like film in the back of a camera. This multilayered, sensory membrane lines the inside back wall of the eye and has the appearance of saran wrap, but is more fragile. It receives light and color and converts them into nerve impulses which go to the brain via the optic nerve.

The retina includes a central macular area and a much larger peripheral area. Two types of photoreceptors - rods and cones - make their home in the retina. There are about 150 million rods, which are sensitive to light, and six million cones, which respond to color. The cones concentrate in the macula, responsible for detailed central vision. We rely on the macula's powers every time we read. Rods are spread throughout the peripheral retina and affect peripheral and night vision. Holding the retina in place and filling the center of the eye is the vitreous humour, a transparent gel.

To function properly, the retina must be attached to the choroid, the thin, blood-rich membrane that lines the inside of the eye.

Click here for eye diagram.