What is Macular Degeneration
Macular degeneration is a progressive eye condition affecting as many as 15 million Americans and millions more around the world. The disease attacks the macula of the eye, where our sharpest central vision occurs. Although it rarely results in complete blindness, it robs the individual of all but the outermost, peripheral vision, leaving only dim images or black holes at the center of vision.
There are several types of macular degeneration, but the fastest growing form is age-related macular degeneration (AMD). AMD is the number one cause of vision loss and legal blindness in adults over 60 in the U.S. As our population ages, and the "baby boomers" advance into their 50's and 60's, we will see a virtual epidemic of AMD. Perhaps 14%-24% of the U.S. population aged 65-74 years and 35% of people aged 75 years or more have the disease.
The impact of developing AMD can be devastating to those who were independent and active prior to the onset of this cruel impairment. Their visual world gradually diminishes into a vague blur, making ordinary daily activities challenging.
There are two types of age related macular degeneration. One form is known as "wet" and the other is "dry". It is possible to experience both forms at the same time, in one or both eyes. It is not uncommon for a patient with the "dry" form to develop the "wet" form later. The onset and progression of either type do not follow any particular pattern. In its earliest stages, AMD can be difficult to diagnose. Sometimes it progresses so slowly that people do not notice a change in their vision. Years may go by before they see an ophthalmologist or eye care professional. In other cases, the deterioration is very rapid and can appear to happen overnight.
What are the symptoms
Most patients report that their first sign of AMD was the rapid onset of prolonged, distorted vision. Straight lines like telephone wires and door frames appear to be wavy. If you notice any distorted or missing areas of vision, consult your ophthalmologist promptly. dry AMD.
Although it rarely causes total blindness, age-related macular degeneration robs those affected of their sharp central vision and can dim contrast sensitivity and color perception. It destroys the clear, "straight ahead" central vision necessary for reading, driving, identifying faces, watching television, doing fine detailed work, safely navigating stairs and performing other daily tasks we take for granted. Peripheral vision may not be affected, and it is possible to see "out of the corner of your eye".
What causes Macular Degeneration
Dry Macular Degeneration
This most common type of AMD affects 90% of the people who have the condition. In the dry form, there is a breakdown or thinning of the retinal pigment epithelial cells (RPE) in the macula. These RPE cells are important to the health of the retina. They are light sensitive and contain hundreds of photoreceptors. The death or degeneration of these cells is called atrophy. Hence, dry AMD is often referred to as atrophic AMD. It is characterized by the presence of drusen (dots of yellow crystalline deposits that develop within the macula) and thinning of the macula. Dry or atrophic MD reduces one's central vision and can effect color perception. Generally, the damage caused by the "dry" form is not as severe as that of the "wet" form. Unfortunately, there is no proven cure or treatment.
Wet Macular Degeneration
This is the more severe type of AMD. Although it afflicts only 10 percent of those who have the condition, it accounts for 90 percent of the blindness caused by this disease. With this type, the membrane underlying the retina thickens, then breaks. The oxygen supply to the macula is disrupted and the body responds by growing new, abnormal blood vessels. These begin to grow through the breaks of the membrane behind the retina towards the macula, often raising the retina.
To visualize this, imagine the roots of a tree growing and spreading until they actually uproot a sidewalk. Then imagine rainwater seeping up throughout the cracks. These abnormal blood vessels (the "roots) tend to be very fragile. They often grow, leak or bleed, causing scarring of the macula. This damage to the macula results in rapid central vision loss. Once this vision is destroyed, it cannot be restored.
A certain percentage of patients with wet AMD can benefit from laser treatment if the blood vessel leak is caught early enough. Both traditional photocoagulation laser (a hot laser) and newer photodynamic therapy (using a photosensitive drug and a cold laser) can be effective in certain cases. There are even some new treatments under development for dry AMD.
What are the risk factors for Macular degeneration
In medicine today you will hear a lot about risk factors. Studies in large populations show that statistically a person's chance of
developing a disease is increased by risk factors. Although the cause of age-related macular degeneration is unknown, a number of factors appear to contribute to the development of the disease. Some of them are outside of your control, like family history. Others are related to lifestyle and you can change them.
Risk factors you CAN control:
- Smoking
- High Blood Pressure
- Exposure to Harmful Sunlight
- Diet
Much attention is being paid to the impact various lifestyle factors may have on the development and progression of Macular Degeneration. High blood pressure and smoking are definitely contributory factors. If you smoke, this is the time to stop. Watch your blood pressure and your diet. Nutrition appears to play a role in the health of the macula. In addition to supplements, there are common food sources for the vitamins,
minerals and other substances necessary for good retinal health. In general, the kind of low fat diet that supports cardiovascular health is one that also contributes to healthy eyes. Finally, protect your eyes from the damaging rays of the sun by using a hat or visor and sunglasses.
How can Macular Degeneration be treated
There is no proven medical therapy for dry macular degeneration. In selected cases of wet macular degeneration, laser photocoagulation is effective for sealing leaking or bleeding vessels. Unfortunately, laser photocoagulation usually does not restore lost vision, but it may prevent further loss.
Recently, photodynamic therapy has proven to be effective in stopping abnormal blood vessel growth in some patients with wet AMD. This new type of laser treatment is far less damaging than laser photocoagulation and is the treatment of choice in many cases.
Early diagnosis is critical for successful treatment of wet macular degeneration. Patients can help the doctor detect early changes by monitoring vision at home with an
Amsler grid.
What can I do about Macular Degeneration
You have control over some of the known risk factors for macular degeneration. If you have macular degeneration, a family history of AMD, or are in the "macular generation" (age 60 or above), you should be particularly attentive to these. However, it is most effective to take these steps well before you are at risk. Healthy habits, started young, will provide the most benefits.
Stop smoking
Tobacco appears to interfere with the absorption of lutein, an important anti-oxidant that protects the retina from damaging ultraviolet light. Smokers are likely to have low levels of lutein and they are at greater risk of developing macular degeneration than non-smokers. So, if you've been trying to quit smoking, here's another good reason to stop!
Control high blood pressure
The eye is a highly vascular organ and it has a rich supply of blood vessels. In fact, the rate of blood exchange in the eye is the highest in the body. The link between high blood pressure and AMD has been the subject of much research.
The only way to know if you have high blood pressure is to have your doctor check for it. There are no symptoms, which is why it is called "the silent killer". If you have high blood pressure, it can be controlled by following your doctor's instructions. This may involve changes in diet and/or medication.
Protect your eyes from exposure to harmful sunlight
Ultraviolet light and blue light can damage your retina and may increase your chances of developing macular degeneration. They can also speed up its development. Therefore, it is extremely important to protect your eyes when you are outside.
Wear a hat or visor whenever you are outside, even on overcast days.
Ultraviolet light passes through cloud cover and is just as dangerous as direct sunlight.
Look for sunglasses that screen 99-100% of ultraviolet A and B rays. Recent research points to blue light (the short wavelengths of the light spectrum) as an even more damaging factor. To be on the safe side, try to find glasses that guard against both ultraviolet rays and bluelight. A certain percentage of sunglasses are mislabeled, so always buy sunglasses from a reputable dealer. Your optician can check your glasses to measure the UV protection.
Most glasses allow some direct sunlight to enter from the top and sides of the frame. There are sunglasses designed specifically for macular degeneration that include side panels and a ridge at the top of the glasses so that all light is filtered. The most helpful colors for blocking out blue light are red, orange, yellow and amber. Because glare is often a problem for people with AMD, choose this protection carefully. You can also have your regular glasses treated with ultraviolet protection - a clear coating that will not interfere with your sight.
Eat a healthy diet
The diet widely recommended as beneficial for cardiovascular good health - low in saturated fats, high in fruits and vegetables - also seems to help people suffering from AMD. A healthy lifestyle that includes regular cardiovascular exercise also contributes to both cardiac and eye health. One explanation: A healthy heart speeds the delivery of essential nutrients to the eyes and hastens the removal of waste products. Other studies have noted beneficial changes from a diet rich in dark green leafy vegetables such as spinach, kale, mustard and collard greens. Antioxidants are present in fruits and vegetables with bright color, including red grapes, peppers, corn, oranges, cantaloupe and mango. For more on Nutrition and your eyes see our food for eyes page.
The importance of good lighting
Good lighting is important for performing tasks like reading or sewing; it also creates a safer environment and helps to prevent accidents. As you age, the amount of light entering the eye is reduced, causing a reduction in visual acuity, contrast and color intensity. The type of lighting and its intensity, color and direction all affect an individuals visual performance.
Too much OR too little light can be a problem for a person with low vision but each person responds differently. Test different kinds and levels of lighting to determine what is most comfortable for you. There are several kinds of lighting, listed in order of the most useful for people with impaired sight:
Full spectrum lighting is the closest to natural sunlight and the most comfortable for people with most visual pathologies. However, it is not as readily available. Full spectrum bulbs are best when used in swing-arm lamps that can direct the lighting onto the task. The OH light is an example of this type of bulb.
Incandescent lighting provides a more yellow, more direct light that is good for close work, like sewing or reading. It is the most common form of light bulb, frequently used in desk or table lamps. The Westinghouse Eye Saver bulb is this type, with a unique feature that directs more of the light on to your work.
Halogen lighting produces the brightest and whitest light. For some people with impaired sight, it can enhance contrast between print and background, but for others they generate too much glare. It also generates a lot of heat.
Fluorescent lighting disperses a blue-white light evenly and without shadows over a wide area. Because it generates a lot of light without using a lot of electricity, it is the type of lighting most often used in public places, such as supermarkets or offices. But it can create increased glare.
Helpful hints on lighting
Put the light directly where it is needed. Use small lamps that swivel and can be raised or lowered to help direct the light.
Direct the light over the shoulder of the eye with the best visual acuity or use lampshades that direct light onto a specific area rather than out into the room.
Wire your overhead fixtures to a dimmer switch in order to increase the amount of light in a room.
Position lamps near frequently used appliances. Under-cabinet lighting provides task lighting in the kitchen or work areas.
Provide extra lighting in stairs and hallways where it can be difficult to move around.
Pay attention to lighting access and control, making sure that switches are located where they can easily be found. Contrast switch plates with the wall color or use switch plates that contain small lights. Consider preset light timers for difficult areas.
Glare
Many people experience an increased sensitivity to glare as they age. Glare can be caused by sunlight, other lighting sources, and reflections from household sources. Drapes or blinds reduce sunlight coming in through windows. Polarized glass or tinted shades will eliminate glare. If possible, choose furnishings with a flat or matte finish. Cover shiny surfaces with a cloth, blotter or construction paper. Carpet and nonslip floor finishes diffuse light to reduce glare. Optometrists can prescribe filters in glasses to reduce problems with glare.