University of Iowa Health Care Department of Ophthalmology and Visual Sciences

Distortions, related to astigmatism , that cause the inability of light rays entering the eye to converge (come together) to a single focus point on the retina . Aberration are divided into two main categories: higher-order and lower-order.

Surgical removal of tissue, typically using a cool beam laser

The area of tissue that is removed during laser surgery

Ability of the eye to change its focus between distant objects and near objects.

This term describes a visual field defect in which either the upper or lower half of the visual field is selectively affected. The selective abnormality often creates a horizontal line across the visual field (known as “respecting the horizontal meridian”). Altitudinal defects occur in retinal vascular disease, glaucoma, and other disorders that affect the eye itself.

Dullness or obscurity of sight for no apparent organic reason, therefore not correctable with glasses or surgery. Sometimes called a lazy eye, wherein one eye becomes dependent on the other eye to focus, usually developed in early childhood. Often associated with strabismus. The conditions that most commonly cause amblyopia are eye misalignment (strabismus), a significant difference in spectacle prescription (refractive error) between the two eyes (anisometropia), or interruption of the light path of one of the eyes (by cataract, scar, tumor, etc.). If amblyopia is not treated before the age of 8, the visual deficit is usually permanent.

Hand held chart featuring horizontal and vertical lines, usually white on black background, used to test for central visual field defects.

Drainage area of the eye formed between the cornea and the iris , named for its angular shape, which is why you see the word "angle" in the different glaucoma names.

Condition of the eyes in which they have unequal refractive power.

Space between the cornea and the crystalline lens , which contains aqueous humor .

Part of the eye anterior to the crystalline lens , including the cornea , anterior chamber , iris and ciliary body .

Micronutrients that destroy or neutralize free radicals, molecules that have been implicated as one causative factor in the stimulation of abnormal cellular reproduction (cancer) and cellular destruction (aging).

Coating on the front or back of glasses lenses, which minimizes the glare for patients who are extremely bothered by glare.

Absence of the lens of the eye.

Transparent fluid occupying the anterior chamber and maintains eye pressure.

device used to treat glaucoma (usually open angle) and diabetic retinopathy using a thermal beam.

Age related macular degeneration: Destruction and loss of the photoreceptors in the macula region of the retina resulting in decreased central vision and, in advanced cases, blindness.

Eyestrain

A modified form of Radial Keratotomy (RK).

Structural defects of the eye in which the light rays from a viewed object do not meet in a single focal point, resulting in blurred images being sent to the brain. An astigmatic cornea is not perfectly rounded like a basketball but has an irregular shape more like the side of a football. Astigmatism is most often combined with myopia or hyperopia .

An inheritance pattern in which a person must inherit two copies of an abnormal gene (one from each parent) in order to develop the disease. If two individuals each carry one copy of an abnormal gene, then each child born to these two parents will have a 25% chance of receiving 2 copies of the abnormal gene and as a result, inherit the disease. Cystic fibrosis is an example of an autosomal recessive disease.

These are visual field defects that extend from the central vision to the natural blind spot. This type of field defect usually represents an insult to the cluster of retinal ganglion cells called the papillomacular bundle.

Also known as Dyschromotopsia. A general term for color vision abnormalities. Heritable dyschromatopsias include red (protan), green (deutan), and blue (tritan) color vision deficits. These deficits may be partial (-omaly) or complete (-opia). Red and green color vision defects are X-linked while loss of the blue receptor (tritanopia) is inherited in an autosomal recessive fashion. Also see: Protanomalous

An enlargement of the cup or central depression in the optic nerve head. Cupping is visible when viewing the back of the eye with an ophthalmoscope. An enlarged cup especially if accompanied by a notch or a small spot of bleeding is a sign of glaucoma. Cupping is a clinical sign that indicates that a large number of nerve fibers in the optic nerve have been lost.

Complete color deficiency affecting the ability to see the color green. There are three possible color vision deficits: red (protan), green (deutan), and blue (tritan). The suffixes –omaly and –opia indicate partial and complete color vision deficits, respectively. Therefore, a person who has deuteranopia has a complete green color deficit.