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Vision Diseases, Disorders & Definitions

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T Definitions


An instrument used to measure intraocular pressure.


Eyeglass lens that incorporates three lenses of different powers. The main portion is usually focused for distance (20 feet), the center segment for about 2 feet, and the lower segment for near vision (14 in).


Portions of this page are excerpted from Dictionary of Eye Terminology, copyright 1990-2006 by Barbara Cassin and Triad Communications. Reprinted with permission.

Some of the information above is reprinted from the National Eye Institute, National Institutes of Health, and is for educational purposes only. Superior Vision strongly recommends eye exams as the best way to diagnose eye conditions and learn more about potential vision problems.