Meaning of light adaptation

light' adapta"tion

Pronunciation: [key]
— Ophthalm. Ophthalm.
  1. the reflex adaptation of the eye to bright light, consisting of an increase in the number of functioning cones, accompanied by a decrease in the number of functioning rods (opposed to dark adaptation).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.