Most commonly, vision loss among older adults is due to clouding of the lens of the eye (cataracts) or to damage to the optic nerve (as occurs in glaucoma) or the retina (as occurs in age-related macular degeneration and diabetic retinopathy). A less common cause of vision loss is blockage of the blood supply to the eye. Eyelid disorders mostly change the appearance of the eye and do not usually cause vision loss, but they can cause discomfort. Severe drooping of the eyelids can also interfere with vision.

Whatever the reason for vision loss, any vision change can compromise an older adult's quality of life and, indirectly, health. For example, poor eyesight may contribute to a car crash or to a fall. Loss of vision can be especially devastating to older adults coping with other problems as well, such as poor balance and hearing loss. In such cases, vision loss can contribute to significant injury and can impair a person's ability to do daily activities.