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Updated January 15, 2009

Definition: The process of administering special pharmaceutical eye drops into the eyes in order to enlarge the pupils.

This allows an eye doctor to examine the structures of the eyes, including the optic nerve, blood vessels and retina, in great detail. Dilation is a key component of a comprehensive eye examination, as it sometimes leads to the detection and diagnosis of certain eye diseases.

Often considered the worst part of an having an eye exam, dilation of the pupils often causes near or close-up vision to be blurred and sensitivity to light. Disposable sunglasses are often provided after the exam to reduce discomfort caused by sunlight. Dilation generally lasts for three to six hours, but it is not uncommon for it to last up to 24 hours for some patients, depending on the eye drops used.

Also Known As: "dilating the eyes"
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