WHAT IS MACULAR DEGENERATION?
Age-related macular degeneration (AMD) is a disease associated with aging that gradually destroys sharp, central vision.
Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. AMD affects the macula, the part of the eye that allows you to see fine detail.
WHAT IS THE MACULA?
The macula is the most important part of the eye and is located in the centre of the retina, the light-sensitive tissue at the back of the eye. The retina instantly converts light into electrical impulses. The retina then sends these impulses to the brain.
Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid rapidly damage the macula. An early symptom of wet AMD is that straight lines appear wavy.
WHAT IS DRY AMD?
Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, you may see a blurred spot in the centre of your vision. Over time central vision is gradually lost in the affected eye.
The most common symptom of dry AMD is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected. Scientists are still not sure what causes dry AMD.
CAN THE DRY FORM TURN INTO THE WET FORM?
Yes. All people who have the wet form had the dry form first. There is no way to tell if or when the dry form will turn into the wet form.
WHO IS AT RISK FOR AMD?
The greatest risk factor is age. Other risk factors include:
- Race. Whites are much more likely to lose vision from AMD than Blacks
- Family history
- Gender. Women appear to be at greater risk than men.
CAN LIFESTYLE MAKE A DIFFERENCE?
Your lifestyle can play a role in reducing your risk of developing AMD.
- Eat a healthy diet high in green leafy vegetables and fish.
- Don’t smoke.
- Maintain normal blood pressure.
- Watch your weight.
WHAT ARE THE SYMPTOMS?
For dry AMD: the most common early sign is blurred vision. As fewer cells in the macula are able to function, people will see details less clearly in front of them, such as faces or words in a book. Often this blurred vision will go away in brighter light. If the loss of these light-sensing cells becomes great, people may see a small–but growing–blind spot in the middle of their field of vision.
For wet AMD: the classic early symptom is that straight lines appear crooked. This results when fluid from the leaking blood vessels gathers and lifts the macula, distorting vision. A small blind spot may also appear in wet AMD, resulting in loss of one’s central vision.
HOW IS AMD DETECTED?
AMD is detected during a comprehensive eye exam that includes:
- Visual acuity test. This eye chart test measures how well you see at various distances.
- Dilated eye exam. Drops are placed in your eyes to widen the pupils. A magnifying lens is used to examine your retina. After the exam, your close-up vision may remain blurred for several hours.
Special investigations may be needed to make the diagnosis and to plan treatment. Optical Coherence Tomography is a test in which the retina is examined using a laser beam. This gives important information for diagnosis and monitoring the response to treatment. A fluorescein angiogram test may be required. A dye is injected into your arm and pictures are taken as the dye passes through the blood vessels in your retina. The test allows your doctor to identify any leaking blood vessels and recommend treatment.
HOW IS AMD TREATED?
Wet AMD can be treated with injections into the eye.
Avastin and Lucentis are the two medicines available to treat wet AMD. They are injected into the eye in a painless procedure done in the consulting rooms and they cause the abnormal vessels to dry up and disappear. Initially 3 injections are given, spaced one month apart. Thereafter injections are required every 1 to 3 months depending on how aggressive the AMD is.
Certain medical aids cover the cost of Lucentis and other medical aids cover the cost of Avastin. These medicines are equally effective although Avastin is much cheaper and was in fact originally licensed for use in colon cancer.
Dry AMD has no treatment yet. In very specific circumstances a particular formulation of vitamins has been shown to be useful in decreasing the risk of developing wet AMD. EyeCapsR and Ocuvite Preservision are two such vitamins. They are available from any pharmacy but your medical aid will unfortunately not pay for them.
WILL I GO BLIND?
In the very worst cases, AMD causes a loss of central vision in both eyes. Reading, driving and recognising faces may become impossible. Peripheral vision is never affected by AMD and therefore sufferers are never ‘white stick blind’. Navigation and basic tasks remain quite possible.