Visual functions deteriorate gradually during the normal aging process. As the number of older population increase rapidly, it is important to educate the senior citizens about the nature of age-related visual functions deterioration and their underlying mechanisms. This literature review compiles all the information concerning the changes in the visual system due to aging process, including: decrease of visual acuity and contrast sensitivity, reduction of orientation discrimination sensitivity and motion direction detection, decline of binocular summation; information processing; visual field sensitivity; wavelength sensitivity; pupil size, and increased tear film evaporation and presbyopia.