Age-related macular degeneration (ARMD) is a degenerative condition of the macula (the central most sensitive part of the retina which provides our sharply focused central vision).
It is the most common cause of vision loss in the western societies in those aged 50 or older, and its prevalence increases with age.
ARMD is caused by wasting away and ageing of the tissues that nourish the retina. This deprives the sensitive retinal tissue of oxygen and nutrients that it needs to function and thrive. As a result, the central vision deteriorates.
Macular degeneration varies widely in severity. In the worst cases, it causes a complete loss of central vision, making reading or driving impossible. For others, it may only cause slight distortion. Fortunately, macular degeneration does not cause total blindness since it does not affect the peripheral vision.
What is the difference between wet and dry macular degeneration?
ARMD is classified as either wet or dry. About 10% of patients who suffer from macular degeneration have wet ARMD. This type occurs when tiny blood vessels start to grow underneath the retina . However, these new blood vessels are very delicate and break easily, causing bleeding and damage to surrounding tissue. In dry AMD the retinal tissue gradually atrophies and initially has a speckled appearance often with yellow dots called drusen.
Fig 1.Central Vision Damaged
Fig 2. Normal Macula area of retina
Fig 3. Wet Macula Degeneration
Fig 4. Dry Macular Degeneration (yellow dots called Drusen, but no blood or fluid accumulation)
What causes macular degeneration?
Macular degeneration may be caused by variety of factors. Genetics, age, nutrition, smoking, and sunlight exposure all play a role.
Signs and Symptoms
Loss of central vision.
- This is gradual for those with the dry type due to a slow wasting away of retinal tissues over a period of years usually.
- Patients with the wet type may experience a sudden devastating decrease of the central vision due to an acute haemorrhage.
Difficulty reading or performing tasks that require the ability to see detail eg recognising faces.
Distorted vision (Straight lines such as a doorway or the edge of a window may appear wavy or bent.)
Detection and Diagnosis
Eye physicians usually diagnose ARMD. Vision testing and examination of the retina through a dilated pupil are the standard clinic examinations. Fluorescein and ICG photography are useful additional tests. Photographs are taken after injecting either or both of these substances in to a vein, and areas of retinal blood vessel leakage are highlighted.
Treatment
- Wet ARMD
In selected cases of wet macular degeneration, laser photocoagulation (destroying the vessel with heat produced by the laser beam) is effective in 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 a significan advance. This new type of laser treatment is far more effective and safer than the regular laser as it localises the damage accurately to the blood vessel without heating up surrounding healthy retinal tissue. It is now the treatment of choice in many cases.
Newer treatments are being developed rapidly. Injections of steroids in to th eye ball may increase the effecacy of photodynamic therapy and is used in some cases. Other drugs are at advanced stages of development which neutralise the chemical stimulus within the eye for blood vessel growth.
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, and should request one form their eye doctor (see below)
Amsler chart. Distortion of the grid pattern can be an early sign of ARMD
- Dry ARMD
Nutrition and macular degeneration
A recent study has shown that for some groups of patients with dry ARMD, specific vitamin supplements can reduce further significant visual loss by about 25%. Consult your eye doctor for further information.
At present no other treatment is available for dry ARMD, other than visual aids and lifestyle advice.
Advice for AMD patients
If you’ve been diagnosed with ARMD, making a few simple lifestyle changes could have a positive impact on the health of your retina.
- Monitor your vision daily with an Amsler chart (Request this from your doctor). By checking your vision regularly, changes that may require treatment can be detected early.
- Take a multi-vitamin with zinc. (check with your eye physician for a recommendation). Antioxidants, along with zinc and lutein are essential nutrients, all found in the retina. It is believed that people with ARMD may be deficient in these nutrients.
- Consult a low vision specialist. These professionals are specially trained to help visually impaired patients improve their quality of life. After a personalized consultation, they can recommend appropriate magnifiers, reading aids, practical tips, and many resources.
- Always protect your eyes with sunglasses that have UV protection. Ultraviolet rays are believed to cause damage to the pigment cells in the retina.
- Quit smoking. Smoking impairs the body’s circulation, decreasing the efficiency of the retinal blood vessels.
- Exercise regularly. Cardiovascular exercise improves the body’s overall health and increases the efficiency of the circulatory system.
These are a few tips to make reading easier:
- Good Lighting. Use a halogen light. These have less glare and disperse the light better than standard light bulbs.
- Shine the light directly on your reading material. This improves the contrast and makes the print easier to see.
- Use a hand-held magnifier. A drugstore magnifier can increase the print size dramatically.
- Try large-print or audio books. Most libraries and bookstores have special sections reserved for these books.
Eye Clinic,
Medical Centre
88 Ahuza St
Ra'anana, Israel
Age Related Macular Degeneration
(ARMD)
