What is the macula?

The retina lines the inside of the back two-thirds of the eye and acts like the film in a camera. At the very centre of the retina is the macula which is the part of the eye that we use for reading and performing other detailed visual tasks. This gives us central vision, as opposed to peripheral vision which is served by the rest of the retina allowing us to recognise our surroundings and movement of objects within this.

What is macular degeneration?

When the macula deteriorates, we call this degeneration and, while this may occur as an inherited condition, it more commonly develops in the aging eye. Why this affects some older people and not others is not understood but it means that the patient may lose the ability to read and do other detailed functions.

Who gets it?

Some are born with an inherited disease which as they grow causes a deterioration in the retina sometime in the early to late teens. This is a very uncommon condition and leads to a loss of reading vision. The most common form of macular degeneration is that which occurs in older people, which may cause a slow gradual deterioration in reading vision or a more sudden deterioration due to haemorrhage or leakage from blood vessels (disciform degeneration).

Can it be prevented?

Up until recently there have been few proven techniques or treatments for the prevention and treatment of uncomplicated age related macular degeneration. (AMD).  It was known that controlling high blood pressure and stopping smoking did greatly improve the outlook for good vision but other therapies were at best speculative.

This changed in 2001 when the National Eye Institute found a combination of vitamins and antioxidants could prevent the progression of the degenerative process, at least for certain groups of patients with AMD. Subsequently, other studies have suggested different combinations of antioxidants might be more useful but the original formulation remains the gold standard for therapy.

In New Zealand, the tablets are called Ocuvite Preserv-Vision and the recommended dosage is for two tablets to be taken twice daily. The tablets are only available on a doctor's prescription. The tablets have few side effects and can be generally tolerated by most people. The tablets are not recommended for smokers. Before treatment is started a photograph is usually taken of each macula.

Prior to the availability of Ocuvite Preserv-Vision most patients with AMD experienced a slow but progressive loss of vision. Some patients however developed complications of AMD, which could produce a rapid and severe loss of vision. One of the main complications of AMD results from the growth of abnormal blood vessels under the retina. Thermal laser treatment can be effective in treating this complication but if the abnormal blood vessels are located directly beneath the macula, heat generated by the laser can cause damage to the adjoining retina.

This potential problem can be overcome by the application of a non-thermal or cold laser used in conjunction with an infusion of a photosensitising dye. This treatment method is called photodynamic therapy, or PDT. Unfortunately, in New Zealand, PDT is not available in the public sector and as re-treatments are often required the therapy can be expensive.

Other complications of AMD are fortunately uncommon but may possibly be treated with surgery. Therefore, it is important for the patient to be aware that an eye specialist should assess any sudden change in vision.  

Visual aids

Patients who lose or have defective reading vision can be helped with low visual aids such as magnifiers or closed circuit television. If the central vision is totally lost, talking books can replace the written word. More sophisticated aids with computers and talking typewriters can enable patients who lose central vision to continue to lead a normal life and occupation.

For further information and support talk to an optometrist or eye specialist. Optometrists are listed in the "Yellow Pages" of your telephone book. Eye specialists are listed with registered medical practitioners at the front of the white pages of your telephone book.

Original material provided by Auckland Eye. Reviewed by everybody.