Approximately 10% of patients 66 to 74 years of age will have findings of macular degeneration. The prevalence increases to 30% in patients 75 to 85 years of age. It is important to note that even with advanced macular degeneration, peripheral vision remains unaffected and you can still get about and the blank area would be no larger than your hand, at arms length. Reading, though can be a big problem.
Macular degeneration is one of the main causes of severe sight loss in the over sixty's and causes progressive loss of central vision, leaving peripheral vision unaffected. The macula is a small part of the eye used for fine detailed central vision. It is densely packed with light receptor nerve cells called cones, this high density enables the high resolution we need to read and resolve fine details. These cone cells are also responsible for colour vision. More peripherally and with progressively lower density are located the rod cell light receptors, these are more sensitive in lower light levels aiding night vision and are also sensitive movement detectors. This set up enables you to be aware and alerted to, for example the presence of a moving bus in your peripheral vision, causing you to look directly at it, at which point you will not only be able to see it as a red number 7 double decker but also hopefully give you enough time to get out of its way!
There are two recognized types of macular degeneration, wet and dry
Wet Macular Degeneration
This tends to start without warning and advances rapidly, tiny blood vessels grow into the retina from the choroid located behind it, these then either leak clear serum or bleed, causing massive and rapid loss of central vision. In the last five years a new treatment has been found for this previously untreatable condition. It involves the injection of an anti venous growth hormone (usually Lucentis) into the eye and, where treatment is successful, causes the vessel growth to regress, stabilizing loss and often improving vision. To be treated successfully there is a relatively small window of opportunity, about five weeks, so if you notice symptoms such as rapid loss of vision in one eye, frequently accompanied by distortion or central blurring it is vital to see your optometrist or GP as a matter of some urgency. If you are at risk, for instance, family history or previous occurrence, it is a good idea to get an amsler grid test, it looks like a large empty cross word puzzle ( most optometrists will be able to give you one) Keep it on the fridge and check for wavy or bent lines regularly.
Dry Macular Degeneration
This tends to develop slowly over years and is a degenerative condition of the macula. It is thought to be caused by changes in retinal metabolism causing a build up of waste products, eventually causing cone receptor damage. This tends to progress much more slowly than wet macular degeneration and may take years to cause significant visual loss.
There is currently no cure for this type of disorder, although there is an increasing body of evidence suggesting vitamin supplements and dietary changes may slow the progression if used in the early stages. Vitamin supplements contain antioxidant vitamins and minerals found in fruit and deep green vegetables like spinach and Brussels sprouts, these are commercially available at chemists and opticians.
One other vital aid to reducing progression is, if you do smoke, give up, there is a strong link between smoking and macular degeneration. There is also a strong link between smoking and death so that it is possible visual loss may not have time to develop.As an ex smoker I spend as much time trying to persuade patients to cease smoking as I do explaining about diet and vitamins.
The early signs of dry macula degeneration are the appearance of yellowish deposits ( drusen) around the macula. Drusen are small clusters of extra cellular material which build up on Bruchs membrane, located just behind the macula between the retina and the choroid. There are a great deal of nutrients passing through this membrane to support the macula's high energy requirements.
The appearance of drusen is a sign of metabolic stress, and whilst the development of small numbers of drusen is regarded as a normal aging change, they are a sign that macular degeneration may develop and is a good time to consider dietary changes ( increased fruit and vegetable, particularly dark green such as spinach) and vitamin supplements.
