Age-related macular degeneration is the leading cause of blindness among the elderly in the developed world.

It is not known how many people in Singapore suffer from age-related macular degeneration, but a community study in 1997 on 574 people aged 60 and above found that 27 per cent had the condition.

Associate Professor Au Eong Kah Guan, head of ophthalmology and visual science at Alexandra Hospital, said macular degeneration afflicts not just the aged, but also the young - especially those with high myopia.

What is macular degeneration?

Macular degeneration is a chronic disease of the eyes caused by the deterioration of the central portion of the retina, called the macula.

The macula is responsible for focusing central vision in the eye.

There are two types of macular degeneration - age-related macular degeneration (AMD) and myopic macular degeneration (MMD).

Prof Au Eong said the causes are likely to be genetic 'but environmental factors also contribute'.

Age-related macular degeneration

AMD is associated with ageing and it gradually destroys the sharp, central vision.

In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and often leads to a loss of vision in both eyes.

AMD occurs in two forms: wet and dry.

Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye.

As dry AMD gets worse, you may see a blurred spot in the centre of your vision. Over time, central vision is gradually lost in the affected eye.

The most common symptom of dry AMD is slightly blurred vision.

While dry AMD generally affects both eyes, vision can be lost in one eye while the other eye seems unaffected.

According to Prof Au Eong, wet AMD is the condition in its advanced stage.

It occurs when abnormal blood vessels behind the retina start to grow under the macula.

These tend to be very fragile and often leak blood and fluid, lifting the macula from its normal place at the back of the eye. Damage to the macula happens very fast.

'With wet AMD, the loss of central vision can occur quickly. One symptom is where straight lines appear wavy,' he said.

There are risk factors associated with AMD aside from age. Women, smokers, people who are obese and those with lighter-coloured eyes seem to be at greater risk.

Citing international studies, Prof Au Eong said that smoking accounts for about 32 per cent of AMD.

'It increases the risk of macular degeneration about 3 times and the condition occurs 10 years earlier in smokers,' he warned.

Myopic macular degeneration

High myopia or being extremely near-sighted can cause macular degeneration.

It is a result of an excessively long eyeball, which puts stress on the retina.

Highly myopic eyes are very vulnerable, especially to sight-threatening complications, of which MMD is the most common, said Prof Au Eong.

If the retina becomes stretched as the eyeball is elongated, it can also lead to blood leakage, retinal separation, and loss of central vision.

'What is most worrying here is that Singaporeans have the world's worst eyesight - one in four children here has myopia,' he said.

While MMD is said to be the seventh greatest cause of blindness of adults in Europe and the United States, and has become the leading cause of blindness in Taiwan, there are no statistics for Singapore.

Treatment and prevention

There is no cure for macular degeneration, but doctors say that antioxidant supplements can slow the progression, particularly of AMD.

These include the antioxidants beta carotene, vitamins E and C, as well as the nutrients zinc and copper.

Wet AMD may soon be treated by injections of a drug containing ranibizumab, a human antibody fragment.

Studies in the US have shown that the jabs are effective in reducing the risk of losing vision from abnormal blood vessel growth under the retina.

A two-year study showed that 95 per cent of people with wet AMD who received monthly injections experienced no significant loss in visual acuity.

There is no known treatment for MMD yet, though there are drugs undergoing clinical trials in the US.

E-mail: juditht@sph.com.sg

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Very low awareness here of macular degeneration

Blindness is the disability most feared by people and yet, few have even heard the term 'macular degeneration'.

But with a rapidly ageing population and the increasing prevalence of severe myopia among Singaporeans, doctors warn that macular degeneration could become a major public health concern.

In order to spread the word about a little-known but devastating condition, and to provide support to those who suffer from it, a group of people got together to form the Macular Degeneration Society (MDS).

The society will be the first self-help group for macular degeneration patients here.

The society's adviser, Associate Professor Au Eong Kah Guan, said that a recent telephone survey conducted by his department last year revealed that 90 per cent of people most feared the loss of sight.

'Yet, only seven in 100 were aware of what macular degeneration was,' he said.

Prof Au Eong, who heads the ophthalmology department at Alexandra Hospital, said this is particularly worrying as the condition is the most common cause of blindness in developed countries.

'And as the proportion of elderly in our population increases, the prevalence of AMD is expected to go up too. The pattern of blindness here will gradually follow that of other developed countries,' he said.

Prof Au Eong said the disease afflicts not just the aged, but also the young - especially those with high myopia.

Retired civil engineer Sam Fong, 63, is concerned enough to set up a support group for sufferers and their caregivers.

Mr Fong, who is the president of MDS, suffers from glaucoma, a condition in which the optic nerve at the back of the eye is damaged and eventually causes blindness.

'People with MD usually cannot perform daily activities such as reading or making a cup of coffee. This results in anxiety and depression. So peer support is crucial to coping with the effects of vision loss,' he said.

'Our aim is to help those with MD to continue living independently with the use of technology. As a group, we also hope to send a strong message to society about the importance of patient support groups in rehabilitation of degenerative eye diseases.'

The Macular Degeneration Society will be officially launched on June 9 at Alexandra Hospital. To register for the launch, please visit the MDS website at www.mds-singapore.org or call Anne on 6238-7387.