Vision Diseases, Disorders & Definitions

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E Definitions

Elective Contact Lenses:

This refers to contact lenses that are worn primarily for cosmetic purposes. The lens wearer does not have one of the conditions described as Medically Necessary Contact Lenses.


Refractive state of having no refractive error. Images of distant objects are focused sharply on the retina without the need for either accommodation or corrective lenses.

Esotropia, cross-eyes:

Eye misalignment in which one eye turns inward (toward nose) while the other fixates normally.

Eximer laser:

Class of ultraviolet lasers that removes tissue accurately without heating it. In refractive surgery, controlled by computer to make precise pre-programmed shavings of eye tissue to produce a given optical correction.

Exotropia, wall-eyes:

Eye misalignment in which one eye turns outward (away from nose) while the other fixates normally.

Extraocular muscles:

Six muscles that move the eyeball.


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.