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Glossary of Terms - P
Common terms to help you learn more about your eyes and vision

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, or can be purchased. Wearing properly manufactured solar eclipse glasses are also an alternative. Find out more about how to protect your eyes from damage

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 the sun’s rays causing damage to the eye. Find out more about protecting your eyes from damage while watching a partial solar eclipse.

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 to mid-40s and continues to worsen until around age 65. You may become aware of presbyopia when you need to start holding reading material- such


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


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