Protecting your vision as you age (AMD)

We live in a very “visual” society. Good vision is usually taken for granted, and is essential for driving, reading, TV watching and recognizing faces in social settings. Many people think that it is normal to lose vision as we age, but this is not necessarily the case.

Age-related Macular Degeneration (AMD) is the most common cause of visual loss in people over 50 years of age. It is a disease that affects the central (macular) portion of the retina. The retina is the neural tissue that lines the inside of the eye and is responsible for sight. The macula is a small part of the retina, but is the area responsible for central (reading and distance) vision.

Macular degeneration is a condition that most often starts in your 60’s and becomes progressively more common with advancing age. The cause is multi-factorial, with genetics (family history), nutrition, vascular disease, light exposure and smoking all playing a role. The disease appears to start in the tissue layer underneath the retina which is responsible for the on-going nourishment and health of the visual cells. There are two main types of macular degeneration, “dry” and “wet”. The dry type is far more common (80 to 85% of cases), and generally has a better prognosis because it progresses more slowly and is associated with better vision. In the dry type of macular degeneration, visual cells are gradually lost, and the fine central vision, including color vision deteriorates. The wet type of macular degeneration is associated with the growth of abnormal blood vessels under the retina, leakage, bleeding and eventual scarring. The visual loss with wet AMD is more rapid and usually more severe. The dry type of AMD can progress into the wet type, and there is no treatment to reverse the damage of dry AMD. There are multiple treatments for wet AMD, including laser photocoagulation, photodynamic therapy (“cold” laser with a photoactive dye) and now the new anti-vascular drugs (“Avastin” and “Lucentis”). Wet AMD can frequently be “dried-up” with stabilization or improvement of vision, but there is a high rate of recurrence. Both types of macular degeneration are more common in women.

Is there anything that you can do to reduce your risk of visual loss from AMD?

There certainly is!! There are some risk factors that you can’t change. For example, a family history of AMD in a parent or sibling increases your risk by 4 to 5 times. Caucasians, blue-eyed people and women all have a higher risk. However, other risk factors such as high blood pressure, hyperlipidemia (high serum cholesterol or triglycerides), smoking and obesity can be controlled and/or eliminated.

In the same way that you protect your skin from the sun with sun block, you should protect your eyes from bright sunlight with dark sunglasses. A large clinical trial conducted by the National Eye Institute demonstrated the protective effect of high dose anti-oxidants on the progression of moderate to severe AMD. These anti-oxidants include vitamins A, C, E and zinc. While the beneficial effects were not seen in individuals with mild AMD or individuals without AMD, it makes sense to eat a balanced diet with healthy portions of fresh fruit and vegetables that contain anti-oxidant vitamins.

Most important of all, it is highly recommended that you have regular eye exams (every 2 years from age 20 to 50 and annually after age 50) to detect AMD and other ocular diseases at the earliest possible stage. It is also important to monitor your vision at regular intervals (test one eye at a time) using an Amsler grid. Any sudden changes in vision should be reported to your eye care professional immediately.

Dr. Howcroft is board certified and fellowship trained in vitreoretinal surgery. His specialty interests include the medical and surgical treatment of age-related macular degeneration, diabetic retinopathy, retinal vascular disease, retinal detachment, ocular trauma and ophthalmic ultrasound. Dr. Howcroft received his medical degree with honors from the University of Toronto and completed 3 years of vitreoretinal surgery fellowships at the University of Toronto and the University of Iowa.

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"Credit: National Eye Institute, National Institutes of Health"