an instrument for measuring visual acuity by determining the smallest amount of light that will render an object just visible.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
photoptometer(fō-tŏp-tŏm′ĕ-tĕr) [″ + opsis, vision, + metron, measure]
A device for determining the smallest amount of light that will make an object visible.
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