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Alaska Blind Child Discovery

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

Delta Center Crescent


Photoscreens can be simply interpreted using "Delta Center Crescent" Method: A light crescent that advances from the pupillary margin (well focused) to within 1.0 mm of the center of the pupil correlates with defocus of 1.50 diopters.

JPOS142:150-8, 2004

Rationale for setting referral criteria

Delta Center Crescent compares favorably with VOIC revised manufacturer's pupil-size-edge criteria

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