Eyes : Meanings of some commonly used terms

Vocabulary that we come across while studying the anatomy of the Eyes – Sense organs for Sight:

Accomodation : The normal adjustment of the eyes to see objects at various distances. The lens is made thinner or fatter by the ciliary body to bring an object into focus on the retina.

Anterior chamber : The area behind the cornea and in front of the lens and iris. It contains aqueous humor.

Aqueous humor : Fluid produced by the ciliary body and found in the anterior and posterior chambers.

Biconvex : Having two sides that are rounded, elevated and curved evenly, like part of a sphere. The lens of the eye is a biconvex body.

Choroid layer : The middle, vascular layer of the eye, between the retina and sclera.

Ciliary body : Structure on each side of the lens that connects the choroid and the iris. It contains ciliary muscles, which control the shape of the lens and secretes aqueous humor.

Cones : Photo sensitive receptor cells in the retina that transforms light energy into a nerve impulse. Cones are responsible for color and central vision.

Conjunctiva : A delicate membrane lining the eye lids and covering the anterior eye ball.

Cornea : Fibrous transparent layer of clear tissue that extends over the anterior portion of the eye ball.

Fovea Centralis : The tiny pit or depression in the retina that is the region of clearest vision.

Fundus of the eye : The posterior, inner part of the eye.

Iris : The colored portion of the eye.

Lens : A transparent biconvex body behind the pupil of the eye. It bends light rays to bring them into focus on the retina.

Macula : Yellow region on the retina lateral to and slightly below the optic disc; contains the fovea centralis.

Optic Chiasma : The point at which the fibers of the optic nerves cross the brain.

Optic Disk : The region at the back of the eye where the optic nerve meets the retina. It is the blind spot of the eye, because it contains only nerve fibers and no rods or cones and is thus insensitive to light.

Optic nerve : The cranial nerve that carries impulses from the retina to the brain.

Posterior chamber : The area behind the iris; contains aqueous humor.

Pupil : The dark opening of the eye, surrounded by the iris through which light rays pass.

Refraction : Bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina. Refract means to break.

Retina : The light-sensitive nerve cell layer of the eye that contains receptor cells called rods and cones.

Rods : Photosensitive receptor cells of the retina that are essential for vision in dim light and for peripheral vision.

Sclera : The tough, white, outer coat of the eye ball.

Vitreous chamber : Area behind the lens of the eye. It contains vitreous humor.

Vitreous humor : Soft, jelly-like material behind the lens, helps to maintain the shape of the eye balls.