Eye deterioration — the five main causes

CATARACTS

OUR EYES and visioncandevelop problems as we get older. Here are five of the most common causes.

This is a clouding of the lens which some people develop in their 40s and others not till their 90s.

If you are told at a routine sight test that you have signs of cataracts, don’t worry — it may take years before they reach the stage where surgery is needed.

But once you have them, surgery is the only treatment — drops don’t help, diet doesn’t help, medicines don’t help.

Thankfully the procedure has a 98 per cent success rate. It is carried out under local anaesthetic using ultrasound, not a laser. An artificial lens is put inside the eye to replace the natural lens which has become cataractous. Sufferers should experience an immediate improvement to their vision.

GLAUCOMA

This is a common condition which can lead to blindness. But with early diagnosis and treatment, it can be controlled. There is no cure, however.

It is caused by increasing pressure within the eye which damages the sight nerve. This pressure increases with age — while 3.5 per cent of 70-yearolds suffer glaucoma, the figure rises to six per cent for 80-year-olds.

The big problem is that glaucoma has no symptoms until it is quite advanced. For this reason, regular screening is important after the age of 40. Drops can be taken to reduce the eye pressure. This treatment is so successful that the amount of glaucoma surgery required is only 10 per cent of what was needed 40 years ago. You must use your drops regularly. Failure to do so will leave you suffering “tunnel vision”.

MACULAR DEGENERATION

Macular degeneration is the greatest cause of poor vision in the elderly today, and it is on the increase.

The macula is a small sensitive area — about a millimetre across — in the centre of the retina which is needed for fine focus and reading vision.

It has a very poor blood supply which means it can become vulnerable to loss of nutrition in older people, causing the cells to die one by one.

There are two main types of agerelated macular degeneration (ARMD) — wet and dry. The dry type is more benign and progresses slowly. The wet type causes leakage of blood within and behind the retina and leads to distortion of vision quite quickly.

It is known that smoking is a risk factor, but the actual causes are still a mystery.

Treatment is by a series of injections into the eye of powerful (and expensive) drugs to control blood vessel formation. By this method, the condition can be controlled (not cured) in up to 50 per cent of cases.

A lot of research is going on, and I am optimistic that a much better solution will be available within a decade. Meanwhile, magnifiers and telescopes incorporated into spectacles are helpful. There is evidence that in dry ARMD, tablets containing various minerals and vitamins may slow the process.

DIABETES

Diabetes involves the breaking of small blood vessels all over the body. When this happens in the eye, it immediately causes deterioration of vision. So, diabetics need to have their eyes monitored regularly. If there is any significant bleeding, it can be treated very well with lasers.

Some diabetics do not develop problems for years, or merely have background eye changes which do not threaten vision, but all diabetics should have their eye examined and the retina photographed once a year.

In severe cases, vitreo-retinal surgery may be needed.

FLOATERS

Caused by changes in the jelly inside the eye, these are benign in 97 per cent of cases. If you get one, you should have your eyes checked just in case. Alan Mushin is a consultant ophthalmologist at Moorfields Eye Hospital