What is Macular Degeneration?
The eye is an incredibly complex organ that "processes" millions of images every day. The analogy is often made between the eye and a camera. The cornea and lens of the eye act the same way as a camera lens does to focus light. They focus the light onto your retina which acts like the film in a camera. The retina receives light and converts it into electrical signals which your brain “processes" and you recognize as images. The retina contains two types of photoreceptors for processing light, rod cells and cone cells. Rod cells which number approximately 125 million, are located in the side walls of the retina. Light focused onto these cells is what gives us our peripheral vision. Rod cells function best in dim illumination. The cone cells, numbering approximately 6 million, are responsible for sharp, straight-ahead vision as well as color vision. The cone cells are concentrated in the macula. When the cells in the macula don't work as well, degeneration or death of these cells may result. As this happens, loss of sharp central vision may occur.
Types of Macular Degeneration
Dry Macular Degeneration
In Dry Macular Degeneration the retinal pigment epithelium, which is responsible for nourishment of the photoreceptors, begins to break down. This causes a buildup of metabolic waste material (known as Dru¨sen) to be left behind. As this happens, the photoreceptors lose nourishment and can degenerate and die. This process, fortunately, is gradual. Patients typically complain that their vision isn’t as sharp as it once was and/or say they need more light to read then they once did. Some patients may notice straight lines look wavy or distorted.
Wet Macular Degeneration
Wet Macular Degeneration causes rapid, severe vision loss. For reasons not fully understood, abnormal blood vessels grow which leak fluid and/or blood, which damages or destroys the photoreceptors. Patients with a diagnosis of dry macular degeneration are at higher risk for developing the wet form. This condition is rapid and can damage and/or destroy vision. Patients with wet macular degeneration usually describe seeing dark spots in the center of their vision. They may also see straight lines as wavy or distorted.
Diagnosis and Treatment for Macular Degeneration
Patients coming for an exam are asked for a complete medical history. This can determine possible causes for vision loss. Symptoms, their duration, as well as family history all play a role in diagnosis of macular degeneration. Patients complaining of distortion and or spots in their vision may be given a test called an Amsler grid. This test consists of crossing lines with a dot at the center. This can help reveal distortions in the central vision. During your comprehensive eye exam, your doctor can examine your retina through your dilated pupils for signs of macular degeneration such as Drüsen or swelling from leaking blood vessels.
Patients diagnosed with dry macular degeneration may have retinal photographs taken, or special 3D scans done to measure the retinal tissue These photographs or scans may not serve any immediate diagnostic purpose. Rather, they are used during future eye exams. Your doctor can compare your retina to past visits to see if any changes have occurred in your condition.
If diagnosed with wet macular degeneration, the doctor may recommend injections of medication called Avastin. After the eye is numbed with anesthesia, the medication is injeciton into the vitreous – or jelly-like substance in the back chamber of the eye. Avastin is administered by an injeciton into your eye as needed at regular intervals (about every four to six weeks); your ophthalmologist will tell you how often you will receive the injection, and for how long.
Self-Help for Macular Degeneration
Whether your eyes are perfectly healthy or you've been diagnosed with macular degeneration, the following suggestions can help you protect your eyesight.
Routine Eye Exams
The American Academy of Ophthalmology recommends that people over the age of 65 have a yearly eye exam. Macular degeneration is the leading cause of vision loss in people over the age of 65. Your eye doctor can see early signs of macular degeneration before you have any visual symptoms.
Filter Out Ultraviolet Light
Increased exposure to ultraviolet (UV) light may increase your risk for macular degeneration. Protect your eyes by wearing glasses that filter out UV light. Most sunglasses you buy will say if they block UV light. It is possible to have your regular glasses coated to filter out UV light also.
It is thought that some nutritional supplements may help slow the progression of some forms of macular degeneration. These are available over the counter in the form of vitamins containing antioxidants and zinc, AREDS II. While more research is currently being done to see if these supplements have any real effect, most doctors recommend them.
Monitor Your Vision
Testing your sight on a regular basis with an Amsler grid is a simple procedure that you can do in your own home. It can show such signs of macular degeneration such as blurry spots, dark areas, or wavy, distorted lines. Early detection of these symptoms is crucial in helping to preserve your sight.
Low Vision Aids
If your vision is already reduced due to macular degeneration, help is available for you. Many devices are available which help you compensate for your vision loss. These help mostly with close tasks such as reading and sewing.
From the American Academy of Ophthalmology