Dealing with Macular Degeneration
What is Macular Denegation?
Macular degeneration is an age-related eye disorder characterized by progressive loss of vision in the center of the visual field due to damage in the retinal central area or macula. It is one of the major culprits in visual impairment and total blindness in old folks starting at age 50. The condition makes it increasingly difficulty to read or recognize faces centered on the visual fields while the side or peripheral vision can remain normal. In the US, it is the leading cause of legal blindness afflicting more than 1.75 million people 55 years and older and is expected to double in 2020.
The macula is the center of the retina and provides the main detailed central vision. The retina inside the eye contains all the receptors that collect and transmit visual signals to the brain with the central portion, or macula, enable 20/20 vision. Its deterioration in aged related macular degeneration (AMD) has to nd there are two types:
- The dry, non-exudative or Atrophic form is the most common and occurs when drusen or cellular debris accumulates between the retina and the choroid containing the blood supply. This accumulation results in a gradual deterioration of the retinal cells in the macula regions leading to a progressive blurring of central vision.
The wet, exudative or neovascular form is more severe and occurs when abnormal blood vessels in the choroids under the retina center and bleed to scar the macula and destroy the central vision. It can even lead to the retina being detached. The condition starts in one and affects the next eye. The loss of central vision is much faster than in the dry type and afflicts 15% of people with AND but accounts for two-thirds of all those with significant visual loss.
Causes and Risk Factors
There is no known clinical cause to the condition but a preponderance of experiential documentation suggests aging, genetic inheritance and a few instances of environmental factors may contribute to its development. While the risk of AMD generally increases with age, a family history of older generations suffering form the condition gives the highest risk to the condition. It has also been observed that Caucasians suffer a higher incidence among races and may have causal link to lightly pigmented skin. Related to this is that people with lightly colored eyeball iris are more likely to develop the condition. Women are also observed to have a high risk.
Environment factors include exposure to ultraviolet light. People with lifelong outdoor exposure to the sun, living near the equator or in high altitudes have high risk to the condition. Certain medical conditions like obesity, syndrome X as well as sleeping disorders like sleep apnea have been associated with the condition. Some drugs like Fosamax prescribed for osteoporosis can predispose the patient to macular degeneration. Lastly, smoking is a well documented risk factor to AND.
Diagnosis is made by the ophthalmologist to confirm the condition once initials signs are detected. The visual field test is standard in vision tests to determine the precise location of lost retinal sensitivity. A microperimetry is the next test using a Rodenstock laser ophthalmoscope to quantify fixation pattern and macular sensitivity. Another test is a fluorescent angiography (FA) where a safe flouresein dye is injected to the arm and with the dye passing through the retinal vessels, the test determines the extent of vascular damage and is often used in prepared for a planned laser treatment. Indocyannine green angiography (ICG) is a similar test using intravenous dyes with infrared wavelength to enable the doctor to view the retina and can reveal more details than an FA.
Treating Macular Degeneration
There is no known medical cure for the dry form of AMD. A deficiency in antioxidants link Vitamins A, C and E along with zinc have noted in people with the condition and supplementation to reduce free radicals in damaging the retina. For any form of macular degeneration, it is recommended the patients take antioxidant supplements.
For the wet form which can cause immediate significant vision loss, there are treatments that can alleviate the condition.
- In 2000, the US-FDA has approved the Photodynamic therapy that uses a light activated drug verteporfin administered intravenously to reveal leaking blood vessels while the ophthalmologist uses a precise Argon laser to cauterize these leaky vessels while leaving the retina untouched.
- There are several drugs currently being evaluated to treat the wet form of AND. They are known to hinder vascular endothelial growth and are showing promising results in improve visions and arresting further macular degeneration.