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Eye Health Glossary

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Ophthalmoscope: An instrument used to examine the retina. There are two types of ophthalmoscopes: direct and indirect. The direct version is used to examine the center of the retina, while the indirect is used when an exam of the entire retina is needed.

Optic nerve: The nerve that connects the eye to the brain. The optic nerve carries impulses of light from the retina to the brain, which then interprets the impulses as images.

Optometrist: A doctor trained to examine, diagnose, treat, and manage some diseases and disorders of the eye. Like ophthalmologists, optometrists are trained to examine the internal and external structure of the eyes to detect diseases such as glaucoma, retinal diseases, and cataracts. Optometrists do not perform surgery and are not trained to care for and manage all diseases and disorders of the eyes. The optometrist is trained to diagnose and treat vision conditions like nearsightedness, farsightedness, astigmatism, and presbyopia.

Peripheral vision: The region of sight where we see objects to the side, out of our direct line of vision.

Photocoagulation: A surgical procedure in which a laser is used to stop bleeding blood vessels or to repair damaged tissue. Photocoagulation can also be used to help treat a tumor found in the eye.

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.

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