What is meant by light and dark adaptation? How do they take place?
Light adaptation is the process of adjusting to bright light after exposure to dim light. This process often takes a minute or two to be completed. Dark adaptation, on the other hand, refers to the process of adjusting to dim light after exposure to bright light. It may take half an hour or longer depending upon the level of exposure.
Light and dark adaptation takes place due to photochemical processes. Light adaptation takes place when the molecules of rhodopsin or visual purple in the rods of the eye get bleached or broken down, as a result of the action of light. Dark adaptation takes place when the light is removed allowing for restorative processes that regenerate the pigment in the rods with the help of vitamin A.