AMD is a common eye problem which usually affects people in middle-old age and results in a deterioration of central vision.
The retina is the light sensitive inner lining of the eye. It receives the image of things we see, transfers this into electrical impulses, and sends these to the brain along the optic nerve. The centre of the retina is called the macula and it is essential to seeing fine detail and colour. If the macula degenerates then seeing to read, to recognise faces, and anything which requires fine discrimination of detail will become difficult.
In AMD, patients may experience:
· blurring of central vision
· distortion of straight lines
· objects may appear smaller in one eye than the other
There are two main types of AMD:
1. Dry (atrophic) AMD: This is the commonest form and it usually progresses very slowly with gradual degeneration of the macula and consequently gradually worsening vision. Sometimes dry AMD can progress to the ‘wet’ type.
2. Wet (exudative) AMD: This is much less common and can cause a sudden and serious deterioration in central vision. It occurs when new blood vessels grow beneath the macula. These new vessels often leak and damage the overlying retina.
There is no treatment for ‘dry’ AMD but as its progress is usually slow only in a few cases does it go on to cause significant loss of vision. However, dietary supplements may be of benefit.
Treatment for wet AMD is sometimes possible, but only if it is detected in the early stage and if the leaking blood vessels occur in a certain location. Wet AMD is often preceded by distortion of straight lines, so people known to be at risk of wet AMD are usually given an Amsler chart to help check for distortion on a daily basis and with the advice to go direct to eye casualty if it occurs.
Newer treatments include a range of drugs such as Lucentis, which are injected directly into the eye, and work by inhibiting the growth of the abnormal blood vessels underneath the macula. Multiple treatments might be necessary, typically 4-6 weeks apart, possibly for 12-18 months.
These treatments are very expensive so they are reserved only for the types of AMD which are most likely to respond well.
Neither type of AMD will affect the peripheral vision which means that even people with advanced AMD can always see to move around. However it still important that sufferers continue to attend routine sight tests with their optometrist so that any other eye problem might be detected, and to preserve the peripheral vision.
Risks and Prevention
AMD can sometimes run in families so near relatives of sufferers should be examined as they get older, and should seek advice on reducing the risk of developing AMD. Regular eye examinations are essential for these people so that the health of the macula can be assessed.
We now have an OCT scanner which will image the macula in remarkable detail, and can help differentiate between dry and wet AMD, allowing us to identify those at high risk, and, if necessary, ‘fast-track’ their referral to the hospital retinal clinics. We would strongly recommend this procedure to those who might be at risk.
Excess exposure to Ultra-Violet light is thought to increase the risk of developing AMD, so wear UV protective sunglasses in bright conditions, especially at high altitudes and abroad.
Poor diet has more recently been identified as a risk, especially if food is rich in oxidants (as in cooked red meats) and low in antioxidants. There is growing evidence that nutrition plays an important role in the development of AMD. Lutein, zeaxanthin and meso-zeaxanthin have been identified as carotenoids most closely linked to a reduced risk of developing AMD. These nutrients are found in most fresh fruit and vegetables but the following contain particularly high levels: Kale, Spinach, Collard Greens, Broccoli, Green Peas, Sweetcorn, Green Yellow & Orange Peppers, and Bilberries.
These may also protect against cataracts, heart disease and some cancers. For those who are at higher risk of AMD, or those identified with early AMD, it is worth considering taking a supplement containing lutein, zeaxanthin and meso-zeaxanthin. We currently recommend MacuShield, it is the only supplement that contains all three of the carotenoids and additionally MacuShield Gold meet the Areds 2 recommended formula (the largest study into the role of nutritional supplements in the development of macula degeneration). Before beginning any dietary supplement you should seek advice from your optometrist or GP.
Smoking is known to be a significant risk factor for AMD, and high alcohol intake is too.
Help for AMD Patients
Practical help for sufferers is available with low vision aids, magnifiers and telescopic spectacles, and an ever increasing amount of material is available in large print format or on audio tape. Tactile bumps can be used to indicate most used settings on ovens, washing machines etc.
Northumberland County Blind Association
Reiver House, Staithes Lane, Morpeth, Northumberland, NE61 1TD.
Tel: 01670 514316
Macular Disease Society
PO Box 16, Denbigh, LL16 5ZA.
Tel: 0800 3282849