A study warned people who suffer from extremely dry eyes may have an increased risk of losing their sight. Some smaller studies suggest there could be links between the ophthalmic conditions that cause vision impairment — age-related macular degeneration, cataracts, diabetic-related eye diseases, and glaucoma — and cognitive decline. Vision impairment can happen anytime during life, but adults 40 years of age or older are at greatest risk of developing eye diseases, such as cataracts, diabetic retinopathy, glaucoma, and age-related macular degeneration.

Compared to those without eye conditions when the British Biobank study began, those with age-related macular degeneration had a 26% higher risk of developing dementia, 11% higher for those with cataracts, and 61% higher for those with diabetic-related eye diseases. Having either diabetes (a systemic disease) in addition to a vision disorder increases dementia risk even more, with a greater risk when diabetic-related eye diseases are present together with systemic conditions.

Eye conditions like glaucoma, retinal detachment, diabetic retinopathy, and age-related wet macular degeneration could suddenly cause your eyes damage — even total, permanent blindness — if you are not seen by your eye doctor and treated for eye conditions like glaucoma early. It is important to be aware of the signs and symptoms of these serious eye conditions, so that if you are experiencing any, you can notify your eye doctor right away.

Some of the many very serious eye conditions need immediate attention by a vision specialist in order to prevent permanent total or partial blindness. Sudden blurred vision may affect either peripheral vision or central vision, and may be a sign of many very serious eye conditions. If you notice red eyes all of a sudden, you might have an eye condition which, in severe cases, could potentially lead to long-term damage to the eyes or even blindness.

Sudden flashes of light in vision may become a common phenomenon when you are older, because it typically happens due to a pull or rub of vitreous fluid against your retina, which is located in the back of your eye. Floating spots are generally harmless, but if they occur suddenly and are joined by other symptoms, like glares or a partial loss of vision from one side, it could be a sign of a more serious eye condition, like a detached retina.

When one or more parts of your eyes or your brain, which are needed for image processing, are sick or damaged, you may experience a serious or complete loss of vision. This may result in reduced 3-D vision, and/or the brain may favour one eye over another, causing vision loss to the unfavored eye (amblyopia, see above).

Without the retina or optic nerve, the eyes cannot communicate with the brain, making it impossible to see. The retina is a thin tissue that lines the inner back layer of the eye, and converts light from the images we see into nerve impulses, which are sent through the optic nerve to the brain, where vision occurs. Located in the back of your eye, the retina contains specialized cells that respond to light and process visual signals, so it is critical for vision.

This hereditary condition causes profound vision impairment, starting within the first years of life, usually presenting itself as night blindness, then progressing to widespread visual loss starting in the peripheral part of the visual field. In high-income countries, where the avertable causes of visual impairment are regularly addressed, the leading cause of blindness is retinal degeneration.

According to the Centers for Disease Control and Prevention, more than 3.4 million individuals aged 40 years or older in the United States fit the definition for legally blindness (visual acuity 20/200 or less, or a visual field 20 degrees or less) or corrected visual acuity (20/40 or less). Blindness or low vision affects 3.3 million Americans older than age 40, according to the National Eye Institute.

There are a number of possible causes for visual impairment, including eye damage and a failure for the brain to properly interpret messages from the eyes. Although the degrees of visual impairment are different, the visual problems that a person faces cannot simply be described in numbers; some people are better at seeing than others of similar visual acuity. Just like you do not think about the color of your eyes everyday, those who have vision loss also do not think about their condition everyday.

If detected and treated early, many eye diseases can be corrected, or the disease process can be slowed down, so that vision loss can be reduced. Unfortunately, about 10% of glaucoma patients who get proper treatment still have a vision loss.

Later, as macular degeneration advances, individuals will experience drifting or blurred vision, and, if the condition continues to worsen, central vision can be lost entirely. The condition causes progressive loss of central vision (the ability to see fine details straight ahead).

Late AMD – At Late AMD, visual loss becomes apparent, either from advanced dry AMD (geographic atrophy) or from wet AMD. Early AMD – Most people will not have any vision loss in the early stages of AMD, so regular eye exams are important, especially if you have more than one risk factor (see below).

Even if you are not experiencing any significant changes in vision, it is important to get regular scheduled eye exams. To detect eye conditions early on and to help prevent vision loss, you should have your baseline eye exam by age 40. Teens with diabetes should definitely get a regular eye exam, as there are no early warning signs of retinopathy.