Macular Degeneration

 

Age related macular degeneration (ARMD) is the commonest cause of blindness in the UK. There are two types of ARMD which are really quite different but both conditions are increasingly common as you get older. Both conditions affect the macular which is the central part of the retina. The retina lines the inside of the back of the eye like wallpaper and is the tissue which detects light allowing you to see. The macular is the most important part of the retina as this is the only part of the retina which can pick up fine detail like seeing letters in a book.

 

Dry ARMD is a common condition in which the central part of the retina develops patches of worn out retina which can no longer see. These patches of missing vision get bigger but only very slowly and are often much worse in one eye than the other so most patients with this condition do not go blind in both eyes. There are no established treatments to prevent progression but there are supportive treatments such as magnifying glass clinics (Low Vision clinic).

 

Wet ARMD is less common and people with wet ARMD often develop a bit of dry ARMD as well. In wet ARMD new leaky blood vessels start to grow into the retina at the back of the eye creating a blister of fluid under the retina. Early on this causes mild blurring and distortion of vision. Distortion means that straight lines look bent. As the condition progresses the new blood vessels develop scar tissue around them and sometimes bleed, both scarring and bleeding can cause permanent severe loss of central vision. Blindness in the affected eye is pretty much 100% within 5 years without treatment. The risk of the other eye becoming affected is about 8% per year.

 

Wet ARMD can now be treated by regular injections into the eye ball of Aflibercept (Eylea), Ranibizumab (Lucentis), or bevacizumab (Avastin). These treatments mean that many patients can improve their vision and the chance of going blind is significantly reduced. The injections stop the blood vessels from growing and reduce leakage and bleeding. They usually last about 4 to 8 weeks and are used as long term treatments with most patients needing about 7 injections in the first year and 4 or 5 in the second year onwards. They should be thought of as a way of controlling the disease not as a one off cure. Research is moving rapidly in this area and treatment regimes are quite variable. Whichever treatment regime you have it is most important to get the condition detected and treated as soon as possible as this gives you the best chance of maintaining good long term vision. The condition can be picked up early by an OCT scanner which some opticians have in their premises. It is easy for even very good optometrists and GPs (and eye surgeons!) to miss the early stages of wet ARMD if they don't have an OCT scanner.

It is possible to assess your likelihood of developing wet age related macular degeneration by having your retina examined. Patients with high risk features such as retinal pigmentation and multiple soft confluent retinal drusen or patients who are already blind in one eye from wet ARMD may wish to consider having three monthly OCT scans to make sure that if they develop wet ARMD it is picked up as early as possible. Standard practice is to recommend use of an Amsler grid to help the patient to detect early changes of wet ARMD although unfortunately this method is not particularly reliable.

 

Smoking is a risk factor for developing visual loss from wet ARMD and a healthy diet with plenty of green vegetables is recommended. There are many vitamin preparations on sale some of which may have a small beneficial effect in some ARMD patients.

 

Unfortunately even with modern treatments some patients will lose vision. No one ever goes completely blind as this is a condition which only affects the centre of your vision. The side vision remains intact so people do not lose their independence. People with poor vision may develop unusual visual symptoms. People often see purple or green flowery patterns, sometimes brickwork effects and sometimes fully formed hallucinations. These hallucinations are called Charles Bonnet phenomenon and may take the form of seeing people or objects that are not really there. This is not a form of madness and can usually be improved by better lighting, explanation and reassurance. Some people find that moving their eyes will help to get rid of hallucinations faster.