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Alaska Blind Child Discovery

A cooperative, charitable research project to vision screen every preschool Alaskan

Pupil Disorders


The pupil is the dark spot in the center of the colored iris. the pupil is the "open window" of the eye and normally closes in bright light and opens wide to improve vision in dim light. the normal pupils are equally round, the react to light,and they get smaller with near focus (accommodation). It is easier to see into the eye for refractions and retinal exams so dilating drops (that last from 4 hours to 7 days) are often given. Photoscreening works better if the pupils are not tiny, therefore screeners dim the room or put children in tents to promote large round pupils.

Certain eye diseases (iritis, coloboma, trauma) may change pupil size and shape. the pupil may also change with conditions and diseases of the brain and nerves (i.e. Horner's Syndrome, Third nerve palsy).

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