Macular Degeneration (MD) is degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in macular degeneration, central vision loss may occur. Macular degeneration is diagnosed as either dry or wet.
Dry macular degeneration is an early stage of the disease and may result from the aging and thinning of macular tissues, depositing of pigment in the macula or a combination of the two processes. Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate in and around the macula. It is believed these spots are deposits or debris from deteriorating tissue. Gradual central vision loss may occur with dry macular degeneration but usually is not nearly as severe as wet macular degeneration symptoms.
With wet macular degeneration, new blood vessels grow beneath the retina and leak blood and fluid. This leakage causes permanent damage to light-sensitive retinal cells, which die off and create blind spots in central vision.
Glaucoma refers to a category of eye disorders often associated with a dangerous buildup of internal eye pressure (intraocular pressure or IOP), which can damage the eye's optic nerve that transmits visual information to the brain. With untreated or uncontrolled glaucoma, you might eventually notice decreased ability to see at the edges of your vision (periphery vision). Progressive eye damage could then lead to blindness.
Glaucoma often is called the "silent thief of sight," because most types typically cause no pain and produce no symptoms until noticeable vision loss occurs. For this reason, glaucoma often progresses undetected until the optic nerve already has been irreversibly damaged, with varying degrees of permanent vision loss.
If you have diabetes, you probably know that your body can't use or store sugar properly. When your blood sugar gets too high, it can damage the blood vessels in your eyes. This damage may lead to diabetic retinopathy.
In later stages, the disease may lead to new blood vessel growth over the retina. The new blood vessels can cause scar tissue to develop, which can pull the retina away from the back of the eye. This is known as retinal detachment, and it can lead to blindness if untreated. In addition, abnormal blood vessels can grow on the iris, which can lead to glaucoma.
Everyone who has diabetes is at risk for developing diabetic retinopathy, but not all diabetics do develop it. In its early stages, you may not notice any change in your vision, but it can lead to the later, sight-threatening form of the disease.
According to the American Academy of Ophthalmology, 95 percent of those with significant diabetic retinopathy can avoid substantial vision loss if they are treated in time. The possibility of early detection is why it is so important for diabetics to have a dilated eye exam at least once a year.
A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. The lens works much like a camera lens, focusing light onto the retina at the back of the eye. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away.
The lens is mostly made of water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it. But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract, and over time, it may grow larger and cloud more of the lens, making it harder to see.
(Definition Source: www.allaboutvision.com. For more information on these and other eye diseases or conditions visit www.allaboutvision.com)