Within certain limits, the eyes adapt to changes in brightness through the changes that occur in the retina and the pupil .
When we move into a dark environment we are temporarily blind, until the eye becomes accustomed to the darkness and the scotopic vision begins to work. Adaptation to the dark implies reflex dilation of the pupil and activation of the rods (cells of the retina responsible for crepuscular vision).
If we expose ourselves to intense light, instead, the pupil contracts and the pigment present in the rods becomes "discolored" (that is, most of the rhodopsin absorbs light and the opsin is in active form).
