Cornea
The refractive, transparent, anterior wall of the eye, equal to 43 diopters power. It is the most important part of the focusing system of the eye and brings objects into focus on the retina.
The cornea is the fastest healing part of the body.
Anterior Chamber
Front cavity or compartment of the eye, located between the cornea and iris. Contains the aqueous humor.
Anterior Chamber Angle
The structure formed by the junction of the iris with the corneo-sclera. Normal fluid drainage from the eye occurs through the trabecular meshwork which lies in the chamber angle. Malfunction of the chamber angle is the cause of glaucoma (high pressure in the eye).
Iris
The colored, circular membrane suspended behind the cornea and
immediately
in front of the lens. The iris regulates the amount
of light entering the eye by
changing the size of the pupil.
Pupil
The central opening of the iris through which light is permitted to enter the eye.
Crystalline Lens
A transparent, colorless body suspended in the front part of the
eyeball, between
the aqueous humor and the vitreous humor. Its
function is to bring light rays to a focus on the retina.
Ciliary Body
A thick ring of tissue lying at the base of the iris. Its muscle fibers serve to change the curvature of the lens and thereby provide fine focusing of light onto the retina.
Zonules
(AKA Zonule of Zinn)
Threadlike filamentous attachments which hold the crystalline lens in place in the eye.
Vitreous Humor
The clear jelly which fills the space between the lens and the retina. It helps to keep the retina intact. Eighty percent of the eye is filled with vitreous.
Sclera
The sclera is tough and fibrous, protecting the interior components of the eye from injury, and makes up the exterior coating of the eye. The sclera forms the entire visible white exterior of the eye.
Choroid
A spongy layer filled with blood vessels. It lies between the sclera and the retina. The choroid nourishes the outer layers of the retina.
Retina
The vital thin layer of tissue composed of millions of visual cells which lines the inside back two-thirds of the eye. The retina is analogous to a film in a camera. It receives light and sends tiny electrical impulses to the brain to give sight.
Optic Nerve
A cable-like structure composed of thousands of nerve fibers which carry impulses from the retina to the brain where visual perception occurs.
Macula
The highly developed central zone of the retina. The macula gives critical vision for reading and discrimination small objects.
Optic Disc
The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye.
Palpebra
Eyelid. Protects the eye, helps remove foreign bodies.
Canthus
The angle at either end of the slit between the eyelids.
Cones
Light sensitive cells in the retina responsible for color vision, daytime vision, and the central portion of the visual field.
Rods
Specialized visual cell in the retina responsible for peripheral and night vision.
Conjunctiva
The clear membrane that lines the eyelids and covers the exposed
surface of the
eyeball. Microbial barrier.