Macular degeneration is the most common cause of untreatable blindness in developed countries. It is becoming more common throughout the world as the average age of the population increases.
What is macular degeneration?
Macular degeneration (also called age-related macular degeneration) is a set of conditions in which the central part of the retina, called the macula, develops degenerative changes due to damage caused by the accumulation of metabolic waste products.
Waste products accumulate in this area because the density of cells is highest here, and because of their high levels of metabolic activity.
This process causes a reduction in function of the macula so that central or reading vision is reduced, sometimes severely.
Macular degeneration usually affects both eyes.
There are two main forms of macular degeneration, the so-called dry form and the wet form.
- Dry form macular degeneration - the accumulation of waste products in the macula damages critical layers of cells. This leads to areas of atrophy (thinning and disappearance) which can gradually combine until the whole central area of the retina is affected.
- Wet form macular degeneration - the process which occurs in the dry form is complicated by the growth of abnormal new blood vessels which leak fluid, protein, fat and blood into the delicate tissues of the retina. This causes damage and loss of function but, more importantly, leads to destructive scar formation at the macula. Once a scar has formed the damage to the macula is irreversible.
Symptoms of macular degeneration
In the early stages of macular degeneration there are often no symptoms.
Dry macular degeneration gradually causes increased difficulty in reading or doing other close-vision tasks, especially in poor light. In more advanced cases it may cause difficulty in recognising faces or with domestic tasks such as cooking. In extreme cases, it can cause legal blindness, but patients usually retain good peripheral vision.
Wet macular degeneration often causes sudden symptoms, especially distortion or a blind spot in the central vision of one or other, or both eyes. This can worsen rapidly.
Who gets macular degeneration?
In general, macular degeneration affects older people, usually in their seventies and eighties. Occasionally people in their fifties or younger can develop it.
Most people show some ageing changes in the retina as they get older but not everyone develops the disease called macular degeneration.
It tends to run in families and some forms seem to be directly inherited.
The condition occurs in all races and in all locations of the world but there is some ethnic variation, some of which may be due to lifestyle factors, especially diet. Women generally seem to be more affected.
Smoking and a high-fat diet are known to be major risk factors.
Can macular degeneration be treated?
There is no effective treatment for dry macular degeneration.
Treatments for wet macular degeneration have been developed over the years with varying degrees of success. Initially laser treatment was used to burn the new blood vessel but this is only possible in a small proportion of cases.
In recent years new treatments have been developed in which drugs are injected directly into the eye to stop and reverse the growth of the abnormal new blood vessel. These treatments target a naturally occurring chemical, called Vascular Endothelial Growth Factor F (VEG F), which stimulates blood-vessel growth. The treatments are thus called anti-VEG F drugs.
This treatment is expensive and time consuming, requiring ongoing injections into the affected eye repeatedly over months or years. It is quite effective at stopping or reversing the early stages of symptoms and will probably become cheaper, more effective and less unpleasant for patients in coming years.
Most patients in poorer parts of the world cannot access or afford these anti-VEG F treatments.
Can macular degeneration be prevented?
Currently, macular degeneration cannot be prevented, but the risk of severe symptoms can be reduced by taking the following measures:
- Periodic eye examinations by a skilled practitioner to detect early signs
- Early attendance to a skilled practitioner if any symptoms develop
- Not smoking
- Eat a healthy low fat diet, especially low in saturated fat and low in total calories
- Vitamin and mineral supplements (specially formulated) for people with signs of macular degeneration, on the advice of a skilled practitioner.
Note: This information is general in nature and is not a substitute for specialist medical advice. Have your eyes checked regularly every two years, even if you have not noticed any symptoms or changes.
About the author
Dr David Moran, Ophthalmologist MB BS (Hons) FRANZCO
David first met Fred Hollows in the mid 1970s, and worked with him on the ground-breaking National Trachoma and Eye Health Program. David has been involved with The Foundation since its earliest days, and was a board member for five years until May 2010. A practising ophthalmologist, David has presented at numerous conferences and authored many papers and publications related to eye health.
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