Macular Degeneration

This is a group of eye conditions that can result in loss of central vision since it affects the central area of the retina called the macula that is responsible for “seeing” fine detail and colour.

The most common form of macular disease is age-related macular degeneration (AMD). It occurs mostly in people over 50 years of age and accounts for almost 50% of all people registered as sight impaired or severely sight impaired. AMD is when the aging process adversely affects the light sensitive cells in the retina due to a reduced supply of oxygen and nutrients carried by the blood. This promotes the growth of poorly formed new blood vessels. The damage to the retina occurs either by an accumulation of waste products or leakage from the new blood vessels. Eventually a scar forms over the macula, the central area of the retina.

There are two main forms of AMD, known as “dry” and “wet”. The “dry” form is most common; it cannot be treated but develops slowly and many people notice only mild difficulties with vision. “Wet” AMD develops more quickly and is more likely to lead to severe difficulties with central vision, although in some people treatment may slow down the progression of the disease.

A few options exist for treating certain types of “wet” AMD only, and these are not useful for everyone with the condition. In a very few cases, laser treatment may be used to seal the leaking new blood vessels if they are not too close to the centre of the macula. A more recent treatment that slows down the rate of progression of the disease is photodynamic therapy (PDT). This is where a light sensitive dye is injected into a vein in the arm. The dye is taken up by the new blood vessels in the retina and light is shone onto the back of the eye to destroy the abnormal vessels. This treatment is only beneficial to less than a third of people with “wet” AMD.

A new approach is the use of anti-angiogenic drugs. These drugs help to stop the growth of new blood vessels in the retina and a tiny amount is injected into the eye using a very fine needle. To be most effective the treatment needs to be started at an early stage of the disease. The drugs that have recently been approved in the USA and Europe are Macugen and Lucentis, both of which have shown some stabilisation of vision, but they are not yet available under the NHS. These drugs, therefore, are currently only available privately in the UK until the National Institute of Clinical Excellence (NICE) has assured itself that the considerable expense is affordable and worthwhile.

There is increasing interest in the role of diet in the development of AMD. This is because the nutrients lutein and zeaxanthin, which are normally present in the macula, are thought to protect the retina from light and agerelated damage. A recent large study in the USA (the AREDS study) has shown that people with more advanced AMD showed less progressive loss of vision if they took supplements of antioxidant vitamins and zinc. Medical advice is needed to ensure that these supplements do not adversely interact with any other medication a person is taking. In this study, no advantage was shown for those people with earlier forms of the disease. No study has yet been published to show that lutien supplements are effective and safe, or what dose is needed. Until those studies have been carried out, advice to people with AMD is to eat healthy diets rich in green vegetables and to stop smoking, which is a major risk factor.

MD is a very serious condition, but even if it is very advanced, the person affected will not go totally blind peripheral vision is unaffected, and a good degree of independence can be maintained with training and use of specialist equipment, issued by social services or available at the Oxfordshire Association for the Blind in Bradbury Lodge.

Cataract

Cataract, commonly associated with ageing, is a condition where the lens inside the eye becomes opaque. Cataracts can also be caused by trauma to the eye or by other eye conditions. Surgery can remove the opaque lens, which is usually replaced by a small plastic lens fitted inside the eye, known as an intra-ocular lens.

This can be a fixed focus lens (for either, close up work, such as reading, or for seeing distance) or a multi-focal lens for distance and close up vision. This procedure is usually very effective. However spectacles may still be needed to give fine focus. If an implant is not appropriate, vision is corrected with glasses or contact lenses.

Diabetic Retinopathy

This eye condition is more likely to affect people the longer they have had diabetes. It involves haemorrhaging of small blood vessels at the back of either or both eyes. The symptoms may include loss of visual field, poor focus/detail perception, double vision and these can become more pronounced as the condition progresses. Laser treatment of the leaking blood vessels has a very good record for halting the loss of vision and preventing further damage. However, it is very important that people with this condition remain under regular review and seek medical advice on any further visual symptoms which may present themselves. Your optometrist / optician can check for this.Everyone with diabetes is advised to have an annual screening by an ophthalmologist or optometrist for the development of sight threatening diabetic retinopathy.

Glaucoma

The risk of glaucoma increases as we get older. It is a condition usually associated with raised fluid pressure in the eye. The most common type of glaucoma has no symptoms and has been called “the silent thief of sight”. If untreated, it may cause blindness. However, in the majority of cases there are several treatments available including drugs, eye drops, conventional and/or laser surgery, which can be used to arrest the progression of sight loss. Tests to check for glaucoma are advisable for anyone over the age of 40.

Some words of advice:

Since three of the four principal conditions leading to visual impairment are treatable they ought not to be amongst the major causes of partial sight and blindness. Early detection of most eye conditions leading to visual impairment increases the possibility of effective treatment, although, in most cases, it is only possible to prevent progression of further sight loss rather than to restore vision to its former level. Eye examinations at two yearly intervals are therefore advisable for every one. More frequent examinations may be required where pathology is present or where there is an increased risk of an eye condition indicated by family history.