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.
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. A newer test which doesn’t require injections is called OCT, and shows acute detail of the neural layers of the retina, revealing collections of fluid and blood.
Treatment
Wet ARMD
Treatment for wet ARMD has progressed significantly in recent times with many patients having their vision saved and even improved especially when caught at an early stage. Treatment includes laser to destroy leaking blood vessels after injection of a fluid in to a vein. This then circulates in the blood stream and localises the laser beam on the required blood vessel reducing damage to surrounding tissue (photodynamic therapy).
More recently great success has been had with drugs such as Avastine and Lucentis which are injected in to the eye ball (under local anaesthetic ), and cause constriction and closure of the the leaking blood vessels. This is the first treatment ever that actually improves the vision in a significant number of patients, and has led to a revolution in the treatment of this condition.
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. Consultation with an optometrist who specialize in Low Vision is often helpful for the provision of more sophisticated magnifiers.
Try large-print or audio books. Most libraries and bookstores have special sections reserved for these books.
