Darkness Causes Myopia in Visually Experienced Tree Shrews

Abstract

Maintaining emmetropia is an active process. After eyes have achieved emmetropia or have compensated for a minus lens, continued visual guidance is necessary to maintain a match between the axial length and the focal plane or for recovery to occur. Absence of light is myopiagenic in tree shrews that have developed with normal diurnal lighting. This result contrasts with the apparent absence of a darkness effect in tree shrews reared in the dark from before normal eye opening.