Age Macular Degeneration

Age-related Retinal and Macular Degeneration

What is Macular Degeneration?

As the eye looks, straight ahead, the macula is the point of the retina upon which the light rays meet as they are focused by the cornea and the lens of the eye. Similar to the film in a camera, the retina receives the images that come through the camera-like lens. If the macula is damaged, the central part of the images is blocked as if a blurred area had been placed in the centre of the picture. The images around the blurred area may be clearly visible.

Macular degeneration is the damage or breakdown of the macula. The eye still sees objects to the side, since side, or peripheral, vision is usually not affected. For this reason, macular degeneration alone does not result in total blindness. However, it can make reading or close work difficult or impossible without the use of special low-vision optical aids.

The retina is the delicate layer of tissue that lines the inside wall of the back of the eye. The macula is a very small area in the centre of the retina. In size, the macula is about the same as a capital ‘O’ in the type of this book. This small area is responsible for our central ’straight ahead’ sight, used for reading and other fine work.

Although macular degeneration most often occurs in older people, ageing alone does not always result in central visual loss. Nevertheless, macular degeneration is the leading cause of impairment of reading and fine ‘close-up’ vision.

Causes and Symptoms

The most common form of macular degeneration is called involutional macular degeneration. This form accounts for 70 per cent of all cases, and is associated with ageing. It is caused by a breakdown or thinning of the tissues in the macula.

About 10 per cent of macular degeneration falls into a category called exudative macular degeneration. Normally, the macula is protected by a thin tissue that separates it from very fine blood vessels nourishing the back of the eye. Sometimes these blood vessels break or leak and cause scar tissue to form. This often leads to the growth of new abnormal blood vessels in the scar tissue. These newly formed vessels are fragile. They rupture easily and may leak. Blood and leaking fluid destroy the macula and cause further scarring. Vision becomes distorted and blurred, and dense scar tissue blocks out central vision to a severe degree.

Other types of macular degeneration are inherited, may occur in juveniles (juvenile macular degeneration), and are not associated with the ageing process. Occasionally, injury, infection, or inflammation may also damage the delicate tissue of the macula.

If only one eye is affected, macular degeneration is hardly even noticeable in the initial stages, particularly when the other eye is normal. This condition often involves one eye at a time, so it may be some time before a patient notices visual problems.

Macular degeneration can cause different symptoms in different people. Sometimes only one eye loses vision while the other eye continues to see well for many years. If both eyes are affected, however, reading and close-up work may become difficult. Macular degeneration alone does not cause total blindness. Since side vision is usually unaffected, most people can take care of themselves quite well.

Color vision may also become dim and other visual disturbances such as words looking blurred can develop due to macular degeneration.

Detection and Diagnosis

Many patients do not realize they have macular problem until blurred vision becomes obvious. The ophthalmologist examines the macula carefully by viewing it with an instrument called an ophthalmoscope to see if damage is present.

• A grid test, in which the patient looks at a test page (similar to graph paper), will be used to check for the extent of sight-loss spots.
• A color vision test will show whether a patient can tell color differences, and additional tests will help to discover conditions that may be causing the macula to deteriorate.
• Sometimes a ‘fluorescing’ angiogram is done. The ophthalmologist injects a dye into the patient’s arm, and then takes photos of the retina and macula. The dye helps to clarify any blood vessel abnormality that might be present.

Macular degeneration can be detected and diagnosed early by an ophthalmologist if periodic eye examinations are part of your health care. Early detection is important since people may not realize that their vision is impaired. Having your eyes checked is especially appropriate if other family members have a history of retinal problems. For patients with macular degeneration, early diagnosis by an ophthalmologist may not only prevent further damage but also aid them in making a visual adjustment with low-vision aids.

Medical and Surgical Treatment

There is no cure for the most common involutional form of macular degeneration. However, ophthalmologic laser surgery has been used to retard the spread of the less common exudative form, but is effective only if it is used in the very early stages of the condition. In this treatment, a focused, intense beam of laser light is used to seal off leaking membranes and destroy new blood vessels. This reduces further loss of vision from the progressive scarring of the macula and the surrounding retina. Antioxidants with Vit E, Vit A, Carotenoids, lutein and zinc, selenium, magnesium are very useful.

An ophthalmologist is licensed to provide total care of the eyes including the diagnosis and treatment of macular degeneration.

Optical Aids and Lighting

Low-vision optical aids often improve vision for people with macular degeneration. Many different types of magnifying devices are available. Hand held stand magnifiers, telescopes and closed circuit television for viewing objects are some of the available resources. Optical aids are either prescribed by the ophthalmologist or by referral to a low-vision specialist or centre. Bright illumination properly directed for reading and close work is often beneficial. Special lamps can also be helpful. Books, newspapers and other items available in large print offer further help.

A patient with macular degeneration can be helped.

Fortunately, visual aids are available to assist many patients in leading a comfortable and relatively normal life. With these devices and proper motivation, people with visual loss can often read, do modified close-up work, and continue to take care of them. The optical aids available are:

1. Magnifying hand-held lenses or spectacles, and
2. Special devices of microscopic and telescopic spectacles wherein a microscope or a telescope is condensed to the size of spectacle glass.

If you are fifty years, or your family has history of retinal problems, you should have your eyes checked periodically for signs of eye problems like macular degeneration. Early detection and subsequent treatment, if indicated, may help prevent additional visual loss.