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Glossary
Anterior Chamber
The cavity in the front part of the eye between the lens and cornea is called the Anterior Chamber. It is filled with Aqueous, a water-like fluid. This fluid is produced by the ciliary body and drains back into the blood circulation through channels in the chamber angle. It is turned over...
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Chamber Angle
Located at the junction of the cornea, iris, and sclera, the anterior chamber angle extends 360 degrees at the perimeter of the iris. Channels here allow aqueous fluid to drain back into the blood circulation from the eye. May be obstructed in glaucoma.
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Ciliary Body
A structure located behind the iris (rarely visible) which produces aqueous fluid that fills thefront part of the eye and thus maintains the eye pressure. It also allows focusing of the lens.
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Cone cells
Cone cells, or cones, are photoreceptor cells in the retina of the eye which function best in relatively bright light. The cone cells gradually become sparser towards the periphery of the retina. Cones are active at higher light levels (photopic vision), are capable of color vision and...
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Conjunctiva
A thin lining over the sclera, or white part of the eye. This also lines the inside of the eyelids.Cell in the conjunctiva produce mucous, which helps to lubricate the eye.
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Cornea
The transparent, outer "window" and primary focusing element of the eye. The outer layer of the cornea is known as epithelium. Its main job is to protect the eye. The epithelium is made up of transparent cells that have the ability to regenerate quickly. The inner layer of the cornea is...
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Hyaloid Canal
A narrow channel that runs from the optic disc to the back surface of the lens. It serves an embryologic function prior to birth but none afterwards
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Iris
Inside the anterior chamber is the iris. This is the part of the eye which is responsible for one's eye color. It acts like the diaphragm of a camera, dilating and constricting the pupil to allow more or less light into the eye.
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Lens
The part of the eye immediately behind the iris that performs delicate focusing of light rays upon the retina. In persons under 40, the lens is soft and pliable, allowing for fine focusing from a wide variety of distances. For individuals over 40, the lens begins to become less pliable,...
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Macula
The part of the retina which is most sensitive, and is responsible for the central (or reading) vision. It is located near the optic nerve directly at the back of the eye (on the inside). This area is also responsible for color vision.
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Optic Disc
The position in the back of the eye where the nerve (along with an artery and vein) enters the eye corresponds to the "blind spot" since there are no rods or cones in these location.
Normally, a person does not notice this blind spot since rapid movements of the eye and...
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Optic Nerve
The optic nerve is the structure which takes the information from the retina as electrical signals and delivers it to the brain where this information is interpreted as a visual image. The optic nerve consists of a bundle of about one million nerve fibers.
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Pupil
The dark opening in the center of the colored iris that controls how much light enters the eye. The colored iris functions like the iris of a camera, opening and closing, to control the amount of light entering through the pupil.
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Retina
The membrane lining the back of the eye that contains photoreceptor cells. These photoreceptor nerve cells react to the presence and intensity of light by sending an impulse to the brain via the optic nerve. In the brain, the multitude of nerve impulses received from the photoreceptor...
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Rod cells
Rod cells, or rods, are photoreceptor cells in the retina of the eye that can function in less intense light than can the other type of photoreceptor, cone cells. Because they are more light-sensitive, rods are responsible for night vision. Named for their cylindrical shape, rods are...
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Sclera
The white, tough wall of the eye. Few diseases affect this layer. It is covered by the episclera
(a fibrous layer between the conjunctiva and sclera ) and conjunctiva, and eye muscles are
connected to this.
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Vitreous
Next in our voyage through the eye is the vitreous. This is a jelly-like substance that fills the body of the eye. It is normally clear. In early life, it is firmly attached to the retina behind it. With age, the vitreous becomes more water-like and may detach from the retina. Often,...
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