Skip to content

Eye Health Center

Font Size

Eye Health Glossary

continued...

Pinkeye: See conjunctivitis.

Presbyopia: The loss of the eye's ability to change its focus to see objects that are near. Presbyopia is not a disease, but a part of the natural aging process of the eye that affects everybody at some point in life. It generally starts to appear around age 40 to 45.

Pupil: The round, dark, central opening of the eye through which light enters.

Refraction: The ability of the eye to bend light so that an image focuses directly on the retina.

Refractive error: A condition in which light bends incorrectly, causing an image to be out of focus. The most common refractive errors are astigmatism, farsightedness, and nearsightedness. When you receive a prescription for glasses or contact lenses from your eye doctor, it's to correct a refractive error.

Retina: The thin layer of nerves that lines the back of the eye. The retina senses light and transmits light impulses to the optic nerve and then the brain.

Retinitis pigmentosa: Any of a number of inherited disorders in which there is a progressive loss of vision. In general, patients with this disorder first experience a loss of night vision, which is then followed by tunnel vision and eventually a loss of central vision.

Retinoblastoma: A malignant tumor that forms on the retina. Retinoblastoma most often affects children under the age of 5. It can occur in one or both eyes.

Sclera: The outer coat of the eyeball that forms the whites of a person's eyes.

Strabismus: A condition in which the eyes are misaligned and unable to point in the same direction at the same time. Crossed eyes is an example of strabismus.

Tunnel vision: A condition in which a person lacks any peripheral vision. Tunnel vision can be caused by any number of conditions including retinitis pigmentosa, untreated glaucoma, and stroke.

Visual acuity: How well a person sees.

Visual field: The entire range in which a person can see, including peripheral vision.

Vitrectomy: A procedure in which the vitreous humor is removed from the eyeball and replaced with a clear gel or liquid. Vitrectomies are done when scarring or blood in the vitreous is causing blockage of vision.

Vitreous humor: The clear gel-like substance found inside the center of the eyeball.

 

WebMD Medical Reference

Reviewed by Brian S. Boxer Wachler, MD on March 28, 2013
1|2|3

Today on WebMD

Woman holding tissue to reddened eye
Learn about causes, symptoms, and treatments.
eye
Simple annoyance or the sign of a problem?
 
red eyes
Symptoms, triggers, and treatments.
blue eye with contact lens
Tips for wearing and caring.
 
Understanding Stye
Article
human eye
Article
 
eye
Video
eye exam timing
Video
 
vision test
Tool
is vision correction surgery for you
Article
 
high tech contacts
Article
eye drop
Article
 

Special Sections