Progressive damage to the macula, the area near the centre of the light-sensitive retina that is responsible for detailed vision
- Increasingly common with age, especially over the age of 70
- More common in females
- Sometimes runs in families
- Smoking and excessive exposure to sunlight are risk factors
Gradual deterioration of the macula, the most sensitive region of the light-sensitive retina at the back of the eye, is known as macular degeneration. The condition leads to progressive loss of central and detailed vision. Affected people become unable to read or to recognize faces. However, the edges of their vision (peripheral vision) remain clear. Usually both eyes are affected.
Macular degeneration is more common in females and sometimes runs in families. The condition usually develops after the age of 70, although there are some rare forms that affect younger people. The risk of developing macular degeneration is increased by excessive exposure to sunlight and smoking.
What are the types?
There are two main forms, but their causes are unknown. In dry macular degeneration, light-sensitive cells in the macula and cells in the supporting layer underneath die. In wet macular degeneration, fragile new blood vessels grow beneath the macula. As the blood vessels leak fluid or bleed, the light-sensitive cells in the macula are damaged.
What are the symptoms?
Macular degeneration causes progressive visual loss over several months. Symptoms may include:
Difficulty in reading, watching television, and recognizing faces.
Distortion of vision so that objects appear larger or smaller than normal, or straight lines appear wavy.
Wet macular degeneration occasionally causes sudden loss of central vision due to rupture of an abnormal blood vessel. The damaged macula becomes scarred, causing permanent visual impairment. Anybody who develops symptoms should consult their doctor promptly, particularly if they experience a sudden distortion of vision.
What might be done?
Diagnosis is made by vision tests and by ophthalmoscopy of the retina. If there is a possibility of wet macular degeneration, then fluorescein angiography may be carried out to check for abnormal blood vessels.
Dry macular degeneration cannot be treated but there is limited evidence that large amounts of vitamins A, C, E, and the minerals zinc and copper may help to slow the progression of the disease. Smokers should also stop smoking.
The early stages of wet macular degeneration may be treated by injections of drugs called anti-vascular endothelial growth factor agents (anti-VEGF agents), which inhibit the growth of new blood vessels under the macula. The injections are given into the eye and are repeated monthly for up to 18 months. Alternatively, the condition may be treated by photo-dynamic therapy. In this technique, a light-sensitive dye is injected into an arm vein and passes through the bloodstream to the eye. In the eye, the dye is activated by a laser and destroys abnormal blood vessels. This procedure may need to be repeated regularly. These treatments can be effective at preventing deterioration of vision, but any vision that has been lost cannot usually be restored.
If sight becomes severely affected, aids such as magnifying glasses may help with tasks such as reading.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.