There are many types of conditions and problems that cause persons to become blind, legally blind, or visually impaired, including disease, age-related conditions, and injury. The types of vision loss that we see most often at GDABVI are macular degeneration, diabetic retinopathy, glaucoma, cataracts, and retinal detachment.
Source: MedlinePlus from the National Institutes of Health.
- Description: Macular degeneration is an eye disorder that slowly destroys sharp, central vision. This makes it difficult to see fine details and read. People commonly found to carry this disease are over the age of 60.
- 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. Damage to the blood vessels is caused by Age-Related Macular Degeneration (AMD or ARMD) and harms the macula in the process.
There are two types of Age-Related Macular Degeneration that lead to vision loss:
- Dry AMD occurs when 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, 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 but it is often found in adults 75 years or older. It is rare to find this in people before the age of 55. In addition to heredity, other risk factors are: Caucasian race, cigarette smoking, high-fat diet, female gender, obesity.
Age-Related Macular Degeneration (animated video on ARMD)
Description: Diabetic retinopathy is a diabetic eye disease that damages the small blood vessels in your retina, the back part of your eye. Diabetes increase 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.
Diabetic Eye Disease and Diabetic Retinopathy (animated video on diabetic retinopathy)
- 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. 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 that lead to vision loss:
- 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 made constantly 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. In most cases of glaucoma, this pressure is high and causes damage to the optic nerve.
Glaucoma (animated video on glaucoma)
- 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. As we age, proteins in the lens begin to break down and the lens becomes cloudy. What the eye sees may appear blurry. In many cases, the cause of cataract is unknown.
Factors that may speed up cataract formation are:
- Eye inflammation
- Eye injury
- Family history of cataracts
- Long-term use of corticosteroids (taken by mouth) or certain other medications
- Radiation exposure
- Too much exposure to ultraviolet light (sunlight)
Cataracts (animated video on cataracts)
- 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 and helps you see the images focused on 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. The cause of this condition is known as posterior vitreous detachment but may also be caused by trauma and very bad nearsightedness. A family history of retinal detachment can also increases your risk.
Another type of retinal detachment that leads to vision loss is known as tractional detachment. This is seen in people who have uncontrolled diabetes, previous retinal surgery, or have chronic inflammation. When the retina detaches, 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.
Retinal Detachment, Floaters, Flashes
For a list of resources for the blind and visually impaired, visit the Resources page!