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Greater Detroit Agency for the Blind and Visually Impaired

16625 Grand River Avenue
Detroit, MI 48227
313-272-3900
information@gdabvi.org

Types of Vision Loss

There are many types of conditions and problems that cause persons to become blind, legally blind or visually impaired. Vision loss is often the result of disease, age-related conditions and injury. The vision loss changes that we see most often at GDABVI are macular degeneration, diabetic retinopathy, glaucoma, cataracts and retinal detachment.

We invite you to learn more about these types of vision loss. For video descriptions, click Videos on Types of Vision Loss.

Source: MedlinePlus from the National Institutes of Health.

Macular Degeneration


Description: Macular degeneration is an eye disorder that slowly destroys sharp, central vision. This makes it difficult to see fine details and read. The disease is most common in people over age 60, which is why it is often called age-related macular degeneration (ARMD, or AMD).

Cause: The retina is at the back of the eye. It changes light and images that enter the eye into nerve signals that are sent to the brain. A part of the retina called the macula makes vision sharper and more detailed. AMD is caused by damage to the blood vessels that supply the macula. This change also harms the macula.

There are two types of Age-Related Macular Degeneration:

  • Dry AMD occurs when the blood vessels under the macula become thin and brittle. Small yellow deposits, called drusen, form. Almost all people with macular degeneration start with the dry form.
  • Wet AMD occurs in only about 10% of people with macular degeneration. New abnormal and very fragile blood vessels grow under the macula. This is called choroidal neovascularization. These vessels leak blood and fluid. This form causes most of the vision loss associated with the condition.

Scientists are not sure what causes AMD. The condition is rare before age 55. It is most often seen in adults 75 years or older. In addition to heredity, other risk factors are: Caucasian race, cigarette smoking, high-fat diet, female gender, obesity.

Diabetic Retinopathy


Description: Diabetic retinopathy is a diabetic eye disease that damages the small blood vessels in your retina, the back part of your eye. Diabetes also increases your risk of having glaucoma, cataracts, and other eye problems.

Cause: It is caused by damage to blood vessels of the retina. The retina is the layer of tissue at the back of the inner eye. It changes light and images that enter the eye into nerve signals that are sent to the brain. Diabetic retinopathy is the leading cause of blindness in working-age Americans. People with type 1 and type 2 diabetes are at risk for this condition.

Glaucoma


Description: Glaucoma refers to a group of eye conditions that lead to damage to the optic nerve. This nerve carries visual information from the eye to the brain. In most cases, damage to the optic nerve is due to increased pressure in the eye, also known as intraocular pressure (IOP).

Cause: Glaucoma is the second most common cause of blindness in the United States. There are four major types of glaucoma:

  • Open-angle (chronic) glaucoma
  • Angle-closure (acute) glaucoma
  • Congenital glaucoma
  • Secondary glaucoma

The front part of the eye is filled with a clear fluid called aqueous humor. This fluid is always being made behind the colored part of the eye (the iris). It leaves the eye through channels in the front of the eye in an area called the anterior chamber angle, or simply the angle. Anything that slows or blocks the flow of this fluid out of the eye will cause pressure to build up in the eye. This pressure is called intraocular pressure (IOP). In most cases of glaucoma, this pressure is high and causes damage to the optic nerve.

Cataracts


Description: A cataract is a clouding of the lens of the eye.

Cause: The lens of the eye is normally clear. It acts like the lens on a camera, focusing light as it passes to the back of the eye. Until a person is around age 45, the shape of the lens is able to change. This allows the lens to focus on an object, whether it is close or far away. As we age, proteins in the lens begin to break down and the lens becomes cloudy. What the eye sees may appear blurry. This condition is known as a cataract. In many cases, the cause of cataract is unknown.

Factors that may speed up cataract formation are:

  • Diabetes
  • Eye inflammation
  • Eye injury
  • Family history of cataracts
  • Long-term use of corticosteroids (taken by mouth) or certain other medications
  • Radiation exposure
  • Smoking
  • Surgery for another eye problem
  • Too much exposure to ultraviolet light (sunlight)

Retinal Detachment


Description: Retinal detachment is a separation of the light-sensitive membrane in the back of the eye (the retina) from its supporting layers.

Cause: The retina is the clear tissue in the back of the eye. It helps you see the images that are focused on it by the cornea and the lens.

The most common type of retinal detachments are often due to a tear or hole in the retina. Eye fluids may leak through this opening. This causes the retina to separate from the underlying tissues, much like a bubble under wallpaper. This is most often caused by a condition called posterior vitreous detachment. However, it may also be caused by trauma and very bad nearsightedness. A family history of retinal detachment also increases your risk.

Another type of retinal detachment is called tractional detachment. This is seen in people who have uncontrolled diabetes, previous retinal surgery, or have chronic inflammation. When the retina becomes detached, bleeding from area blood vessels may cloud the inside of the eye, which is normally filled with vitreous fluid. Central vision becomes severely affected if the macula, the part of the retina responsible for fine vision, becomes detached.