Glossary of Eye and Vision Terms

Common terms to help you learn more about your eyes and vision

keratitis acanthamoeba

Acanthamoeba keratitis is sometimes referred to incorrectly as “keratitis acanthamoeba.” Find out more about acanthamoeba keratitis

Laser

Surgical tool using an intense beam of light energy to close rips, make holes, destroy new vessels (photocoagulation), or to open channels as in the treatment of glaucoma.

Legal Blindness

Visual acuity that does not exceed 20/200 in the better eye with correcting lens; field of vision no greater than 20 degrees in its widest angle (Visual acuity of 20/200

Lens

The transparent disc in the middle of the eye behind the pupil that brings rays of light into focus on the retina.

Low-Vision Aids

Powerful optical devices useful to persons with vision impairments that are not successfully corrected by the usual prescription lenses.

Macula

The region of the retina that helps provide best central vision. The fovea is at the center of the macula.

Myopia

Myopia (my-OH-pea-uh), or nearsightedness, is a vision condition in which distant objects appear blurred – such as roadway signs, the board at school, faces, or the television set across the

Near Vision

The ability to perceive objects distinctly at normal reading distance (usually about 14 inches from the eye).

Nearsightedness

Myopia (my-OH-pea-uh), or nearsightedness, is a vision condition in which distant objects appear blurred – such as roadway signs, the board at school, faces, or the television set across the

Optic Disk

Head of optic nerve; formed by the meeting of all retinal nerve fibers in the retina.