Glossary of Eye and Vision Terms

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

Optic Nerve

Special nerve of sight beginning in the retina as the optic disk, which carries messages from the retina to the brain, resulting in visual images.

Partial Solar Eclipses

Partial solar eclipses occur when the moon passes in front of the sun, but only blocks part of the sun. Viewing a partial solar eclipse can expose your eye to

Pinhole Projector

A pinhole projector is a device for safely viewing a partial solar eclipse or total solar eclipse. These can be made easily by hand using tape and a shoe box,

Presbyopia Definition

Presbyopia (prez-bee-OH-pea-uh) is the slow loss of your eyes’ ability to focus objects up close. It’s a common condition that occurs with age, and usually becomes noticeable in the early

Prevalence

Total number of cases of a problem or disease in the population at a given time.

Pupil

The opening in the center of the iris that appears as a black dot and through which light enters the eye.

Refraction

Measurement of the focusing characteristics of the eye to determine refractive error and the need for prescription glasses.

Retina

Innermost layer of the eye containing light sensitive nerve cells and fibers connecting with the brain through the optic nerve and nourished by a network of blood vessels; receives image

Retinitis Pigmentosa (RP)

Retinitis pigmentosa is a group of related eye disorders caused by variations in 60 genes that affect the retina (terms highlighted in teal are labeled on the diagram of the

Retinopathy

Retinopathy is disease of the retina. There are many types of retinopathy. All types of retinopathy affect the small blood vessels of the retina. Some examples of retinopathy are diabetes-related

Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is an eye disease that affects premature or underweight babies (babies who weigh less than 3 pounds at birth). Abnormal blood vessels grow in the retina,