Anatomy of the Eyeball

The eyeball is a hollow fluid-filled structure composed of three layers—the fibrous, vascular, and inner layers.

The superficial fibrous layer has two regions—sclera and cornea.

The Sclera, the white of the eye, mainly covers the posterior side of the eyeball.

The cornea is an anterior and transparent layer covering the remaining eyeball.

The middle vascular layer has three regions—choroid, ciliary body, and iris.

The choroid is the posterior portion rich in blood vessels. The ciliary body is the anterior continuation of the choroid.

The Iris is the colored part of the eye, which can be brown, grey, amber, blue or green. Its central circular opening, called the pupil, allows light to enter the eye.

Posterior to the iris is a flexible biconvex lens. It helps focus the image on the innermost layer—the retina—and facilitates clear vision.

The retina has an outer pigmented layer that absorbs excess light rays. Its inner neural layer has photoreceptors—rods that help us to see dim light and cones that allow color vision.