Why and How Macular Degeneration Affects Vision 0
Why and How Macular Degeneration Affects Vision
Age-Related Macular Degeneration (AMD) affects vision because the macula is part of the retina of the eye. The macula is located behind the lens on the back of the eyeball and helps images get to the optic nerve so they can be interpreted by the brain. The macula has the specific purpose of focusing fine details and enables people to read, drive, and see things like facial expressions.
So when the macula starts to break down and become dysfunctional, the central field of vision also suffers, though it leaves peripheral vision intact. This often causes confusion for those who are close to the person with macular degeneration because their eyes still look normal from the outside, so people don’t know why so much is missed by the one with AMD. At its worst form, what a person with AMD sees is almost like those scratcher cards that haven’t been scratched off yet — a blank circle covering the center area of where they look. Before that, the central vision may be distorted or partially “scratched.”
People with AMD are not blind, but they don’t have a full range of vision either. They are somewhere in between – as the former National Association for Visually Handicapped’s founding director, Dr. Lorraine Marchi, coined the phrase for AMD as being “hard of seeing.” A loved-one with AMD may not see the eyes of the person they are looking at, but they can usually see the general shape of the face. Since they know where the eyes are generally located, they can look at the eyes without seeing them.
In America, AMD — usually in the form of age-related macular degeneration— is the leading cause of vision loss for those who are over the age of 60. Studies show that exposure to UV rays, obesity, and smoking may increase the risk of AMD, and it seems to be more prevalent in Caucasians than in African-Americans. It has hereditary links and is also more common among women than men. Though there are two forms of AMD (wet and dry), 90% of those suffering from AMD have the dry, less severe form.
No cure has been found yet for AMD. With early detection, there are treatments that slow the progress of the disease, extending full vision longer. Have you been diagnosed with macular degeneration?
Dr. Travis Zigler
SOURCES: http://www.visionaware.org/info/your-eye-condition/age-related-macular-degeneration-amd/how-does-amd-affect-vision/125 http://www.vistaeyecare.net/your-eye-health/eye-diseases/macular-degeneration/
- Dr. Travis Zigler
- Tags: age related macular degeneration AMD distorted vision Dr. Travis Zigler Dry AMD eye love Eye Love Blog eye love the sun leading cause of vision loss Macular Degeneration Macular degeneration support community symptoms of amd treatments for AMD vision loss Vision problems wet AMD
Macular Degeneration In Young Populations 0
Macular Degeneration in Young People
Juvenile macular degeneration is an inherited condition. The defective gene that causes it can be inherited from one or both parents. It occasionally shows in children, teenagers and young adults, although congenital forms of macular degeneration are relatively rare.
People with Best Disease may not have any symptoms at all. The progression of the disease is also unpredictable because each person who has it is a unique case. They usually have it in both eyes, but the progression could even be different in each eye. If a child has a parent with Best Disease, they have a 50% chance of having it too.
It develops between ages 3 and 15, but may not be diagnosed until vision loss starts later in life. Its symptoms and stages are the same as those noted for Vitelliform Macular Dystrophy below.
Vitelliform Macular Dystrophy
Vitelliform Macular Dystrophy presents itself in adults. Less than a quarter of them have the mutated genes thought to be responsible for this dystrophy. The cause for the rest of the cases is unknown.
There are several stages in Vitelliform. They are the same no matter how the disease presents. People can skip stages or never progress beyond the first few. It is different for each sufferer. In the first stage, everything looks normal, but electro-oculography retinal tests begin to register abnormalities.
During stage two, lipofuscin builds up beneath the macula. Lipofuscin is a fatty yellow pigment that resembles an egg yolk, hence the disease having a name that means yolk (vitelline). Lipofuscin damages photoreceptor cells in the macula and can be seen during an eye exam. The rest of the eye looks normal.
In stage three, the lipofuscin can break through the retinal pigment epithelium (RPE) and accumulate in the subretinal space. During stage four, the lipofuscin breaks up and gives the build up and appearance of scrambled eggs. Vision deteriorates at this point. In stage five, the lipofuscin disappears, but the damage to the RPE remains.
In stage six, a yellow cyst forms under the RPE. Vision can remain normal, or as normal as the accumulated damage allows, for years. When the cyst erupts, the fluid deposits in the RPE and macula. It causes further vision loss though the patient retains their peripheral vision.
Stargardt's disease is the most common of all types of juvenile macular degeneration. Usually, both parents have a recessive gene for the disease, meaning that they do not have it and may not know they carry the gene. There is a form of Stargardt's disease that can be inherited from a parent who has a dominant gene. In that case, the parent definitely has the disease too.
A child with Stargardt's disease may complain of vision loss, but tests may come back normal. That is why it is often diagnosed later in life, as children are often not the best at relaying their symptoms. Symptoms may include blurred or distorted vision, small blind spots, moving blind spots, difficulty adjusting to different levels of light, and light sensitivity. There may even be a loss of color vision, and loss of depth perception.
As it progresses, changes will appear in the choroid (a layer of blood vessels that feed the macula). Later, small yellowish white flecks will appear in their retinal periphery. Unfortunately, not much can be done for treatment of Stargardt’s, although research continues to dive into future options. Do you know anyone with congenital macular degeneration?
Dr. Travis Zigler
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- Dr. Travis Zigler
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