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Health, Beauty & Fashion

Silent thief of sight

Get your eyes checked regularly to ensure that any signs of visual impairment can be treated at an early stage
The Straits Times - July 14, 2011
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Silent thief of sight

Mr A, a 63-year-old man, came to see me complaining of mild blurring of vision in both eyes for the past few months.

There was no eye discomfort and he had no other eye complaints.

His vision was still reasonably good. He had mild cataracts but his eye pressure (intraocular pressure) was raised at 26mmHg in the right eye and 25 mmHg in the left.

Normal eye pressure is generally less than 21mmHg.

Examination of his optic nerve (the nerve that transmits visual impulses to the brain) showed that there was a significant enlargement of the optic nerve cup, a characteristic feature of nerve damage from glaucoma.

A visual field test which assesses nerve function confirmed that he had already lost 20per cent of his vision.

The patient was started on anti-glaucoma eye drops to reduce the eye pressure. This normalised his eye pressure and stabilised his condition.

Follow-up examinations confirmed that his glaucoma was well under control and there was no progression of his condition.

Mr A's case is a typical story for patients with glaucoma.

Glaucoma is the leading cause of irreversible blindness in the world. In Singapore, 3 to 5 per cent of the population has glaucoma.

It is an eye disorder in which the optic nerve is damaged, usually from an increase in eye pressure. The rise in eye pressure is usually due to a blockage of the outflow of fluid from the eye.

Glaucoma causes permanent damage to the nerve, resulting in loss of vision and eventual blindness.

It can be divided into two main categories: open-angle and closed-angle glaucoma, based on the anatomy of the 'angle', which is the area where fluid drains out of the eye.

Closed-angle glaucoma, which is more commonly seen in Asians than in Caucasians, arises when the outflow passage is narrowed and closed.

In acute glaucoma, a patient can develop a sudden increase in eye pressure, resulting in severe eye pain and sudden loss of vision.

The patient should quickly seek medical attention. If the pressure is not controlled promptly, the patient may suffer permanent nerve damage within a few days.

Often, glaucoma occurs as a chronic form where there are no obvious symptoms. This form of glaucoma is associated with painless progressive loss of vision and can be difficult to detect.

Most patients do not realise that they have glaucoma till there is already significant damage to the nerve.

In the initial stage of the disease, patients begin losing their peripheral visual field and this gradually progresses to involve the central vision, which in the late stage is termed 'tunnel vision'.

I explained to Mr A that the aim of glaucoma management was to preserve his current vision and to prevent further nerve damage.

Mr A asked if there was any treatment that can restore his damaged nerves back to normal.

This is a very common question raised by patients who have lost vision.

I explained that nerves that are already irreversibly damaged could not be rejuvenated.

It is therefore important to protect the nerves from further damage and to preserve his current vision.

I emphasised that he would need to be on long-term treatment for his glaucoma.

This case demonstrates the insidious nature of the disease.

Mr A, like most patients with glaucoma, did not realise initially that he had this disease.

By the time he came to see me, he had already lost 20 per cent of his vision, which suggests that he probably already had glaucoma for several years.

Because of the lack of obvious warning signs, patients often do not realise they have glaucoma until there is already significant nerve damage and visual loss.

Hence, it has been aptly nicknamed the 'silent thief of sight'.

Advances in treatment have enabled us to more effectively arrest or slow down the progression of the disease.

New types of medication can achieve better eye pressure control with fewer side effects.

In most patients, the eye pressure can be lowered with just eye medication.

Laser treatment may also be used to help open up outflow channels, thereby reducing the eye pressure.

In patients where the pressure is not optimally controlled with medication, surgery may be needed to create a bypass channel to allow fluid to flow more freely out of the eye.

Early detection and treatment is the key to preventing blindness in glaucoma.

As glaucoma usually affects the middle aged or elderly, it is prudent for those above 45years of age to have their eyes checked regularly.

Fortunately for Mr A, the disease was detected and treatment helped to halt the progression of the disease.

However, not every one is as fortunate as he is. Many people go blind from glaucoma because they seek treatment too late and severe damage has already occurred.

Those with visual problems should have their eyes checked so that potentially serious conditions like glaucoma can be detected and treated early.

Dr Leonard Ang is the Medical Director of The Eye & Cornea Transplant Centre and the Premium Lasik Surgery Clinic. He has won more than 27 international and local scientific awards, including the Singapore National Academy of Science Young Scientist Award and the Singapore Clinician Investigator Award and has written more than 90scientific publications and book chapters.



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