A B C D E F G H I J K L M N O P R S T U V W

MACULAR DEGENERATION

What is Macular Degeneration ?

The macular is the centre area of the retina which sub-serves detailed vision and colour vision. The retina lines the internal part of the back of the eye. Light is focused on the sensitive photoreceptor cells (the cones), which then produce signals which are transmitted by the optic nerve to the brain. The macular has a very high oxygen demand and is therefore close to a very vascular layer full of blood vessels (the choroid). It is separated from this layer by a specialised pigment layer (the pigment epithelium). Macular degeneration occurs when the layers of the retina become distorted or disrupted generally by the process of ageing. The pigment layer is responsible for clearing up the molecular debris resulting from photoreceptor activity. When this begins to fail with ageing deposits called drusen collect near the pigment layer disrupting the delicate architecture. There are basically two types of macular degeneration called "dry" degeneration and "wet" degeneration.

Dry degeneration is a wasting away of the pigment layer and photoreceptor layer causing a slow loss of detailed vision often over a period of years. Vision is not usually severely affected. Wet degeneration occurs when the layer separating the blood vessel layer (the choroid) and the photoreceptor layer becomes disrupted with ageing and accumulations of deposits (drusen). Blood vessels then break thought under the retina when they can bleed abruptly causing sudden disturbance and loss of vision. Scarring eventually forms often described as a disciform scar. Vision can be severely affected with this condition.

How does Macular Degeneration occur ?

The common form is really due to ageing and often called age related macular degeneration. However exposure to light, particularly UV / Short-wave length blue light over many years is an important factor which induces change in the retina. Heavy cigarette smoking has been identified as being a risk factor and to a lesser degree having high blood pressure. Macular degeneration can occur in young age groups and is then often a type that runs in families (genetic).

Treatment Involved in Macular Degeneration

Macular degeneration is a common condition in individuals over the age of 70 and unfortunately for the majority of people there is no proven effective treatment. Investigation of the condition by an Eye Specialist may involve special photography of the macular and blood vessels for the back of the eye. This involves injecting a dye into the blood stream (via a vein in the arm or hand), and the dye highlights the blood vessels and the transit is recorded by photography. Fluoroscein is generally used though Idocyanine Green may also be used. There is not really any effective treatment for dry degeneration however a good diet with normal vitamin intake is important. Stopping or cutting down smoking is sensible. This would not reverse any existing change. Some Practitioners may recommend vitamin supplements and antioxidants. The wet form (called sub-retinal neovascularisation) can in some cases be treated by laser therapy. This is unfortunately possible only in a minority of cases. The reason being that in most cases the abnormal blood vessels involve the very centre of the retina and to destroy them with laser would inevitably destroy the macular as well with loss of vision. When the blood vessels develop just near the macular, laser can be applied to destroy the abnormal blood vessels. This is usually not painful and will take about 15 minutes undertaken as an outpatient in the Eye Clinic. Unfortunately the blood vessels often recur either adjacent to the original area or in a separate area. Further treatment would then be necessary.

A great deal of research is currently taking place in the area of macular degeneration. Many new treatments are being evaluated. This includes radiotherapy to the eye using certain drugs that inhibit blood vessel growth for example, Thalidomide. A recent treatment which may have improved results over standard laser therapy is photodynamic therapy (PDT). This involves injecting a dye into the blood stream which allows increased uptake of the laser energy into the affected blood vessel. This is designed to localise the laser to the abnormal vessels reducing the damage to the surrounding retina. Surgery to remove the abnormal collections of vessels is possible but is generally reserved for younger individuals with localised specific areas of growth of blood vessels without widespread degeneration. This occurs in certain inflammatory eye conditions and genetic eye conditions.

A complex procedure of rotating the retina in the back of the eye to move the damaged area has been employed. However this expensive and time-consuming procedure is not without risk and cannot be considered to be widely employed. Claims in the media are regularly made of "wonder" treatment for macular degeneration. Unfortunately currently there is no really effective treatment for the majority of sufferers. However low visual aids can help individuals to see better and to continue working. These include telescopes to improve distance vision and magnifying lenses for reading. Closed circuit televisions (CCTV) systems and optical scanning linked to a standard personal computer (PC) can also help with reading as the text size (font) on the PC can be increased in size until it is readable.

After Treatmentfor Macular Degeneration

Following laser treatment for wet macular degeneration the individual will be aware of an area of missing vision near the centre of vision. It is important to report to the specialist any new distortion or blurring which may mean that a new area of new blood vessels are forming near the originally treated area. Any individual has been identified as having the predisposing condition of macular degeneration which is collections of drusens at the macular is advised to check the vision of each eye daily for any change of vision or distortion of straight lines. The eye clinic may provide a chart with a grid pattern to use as a test for distortion (Amsler Chart). Any distortion should be reported to the eye clinic and an early appointment arranged.

If Macular Degeneration is Left Untreated

The condition of macular degeneration generally progresses over time and abrupt change may happen with wet degeneration. However the condition involves the central retinal area and individuals will maintain peripheral vision and generally retain their independence.

Effects on Family of Macular Degeneration

Support for elderly relatives with poor vision is very important. To ensure the house or flat is safe, for example for cooking. Discussing blind or partial sighted registration is important, Social Services can then be involved if necessary.