The ability to see at night or in light of low intensity. It results from dark adaptation in which the pupil dilates, rhodopsin increases, and the intensity threshold of the retina is lowered. Any decrease in the oxygen content of the blood is accompanied by some loss of night vision. Thus, smoking cigarettes or being in an atmosphere with decreased oxygen content decreases night vision.
The capacity of the eye to perceive in low-light conditions. Reduced night vision can result from an innate retinal issue, deficiencies in vitamins, or excessive exposure of the eye to sunlight.
The capacity of the eye to see in low light conditions. Impaired night vision can result from a natural flaw in the eye’s retina, lack of certain vitamins, or prolonged exposure to sunlight.