SINGAPORE: Loss of vision or blindness is a major handicap that significantly affects a person’s quality of life.

Up to 80 per cent of blindness in people can be avoided. Often, they are the result of complications from diabetes or other medical conditions.

With the growing affluence in Asia, and the changes in lifestyle and increased longevity that come with it, more people are suffering from diabetes. According to the 2004 National Health Survey in Singapore, 8.9 per cent of males were diabetic, compared to 7.6 per cent of females. Indians who are diabetics topped the list at 15.3 per cent, compared with 11 per cent Malays, and 7.1 per cent Chinese. These figures should hold true with Asians elsewhere with similar lifestyles.

Diabetic retinopathy is a complication of diabetes that results from damage to the blood vessels of the light-sensitive tissue at the back of the eye, which is the retina.

“In fact, diabetic retinopathy is the commonest cause of blindness in the adult working population in developed countries,” said ophthalmologist Dr Ian Yeo Yew San, a consultant with the Singapore National Eye Centre (SNEC), an institution of the SingHealth group.

When a person has diabetes, the body does not use sugar (or glucose) properly. If the blood sugar level is too high, the person’s natural lens may swell, causing blurred vision. Eventually, too much sugar in the blood can damage the tiny blood vessels that nourish the retina, resulting in diabetic retinopathy.

The longer a person has been diabetic, the higher is the chance of the blood vessels in his or her eyes becoming damaged. “About 60 per cent of patients having diabetes for 15 years or more will have some blood vessel damage in their eyes, and a percentage of them are at risk of becoming blind from it,” added Dr Yeo.

Signs and symptoms of diabetic retinopathy

Diabetic retinopathy usually affects both eyes. At first, it may cause no symptoms or only mild vision problems. As the condition progresses, other symptoms may include:

Spots floating in one’s vision

Blurred vision

Dark streaks or a red film that blocks one’s vision

Poor night vision

Eventually, however, diabetic retinopathy can result in blindness.

Screening for diabetic retinopathy

As part of the eye examination, your doctor may do a retinal photography test called fluorescein angiography.

First, your doctor will dilate your pupils and take pictures of the inside of your eyes.

Then a special dye will be injected into a vein in your arm. More pictures will be taken as the dye circulates through your eyes.

Your doctor can use the images to pinpoint blood vessels that are closed, broken down, or leaking fluid.

Your doctor also may request for an optical coherence tomography examination to be done. This imaging test provides cross-sectional images of the retina that show the thickness of the retina and whether fluid has leaked into retinal tissue.

Types of diabetic retinopathy

Background retinopathy is an early stage of diabetic retinopathy and progresses slowly over the years. Tiny blood spots or fatty deposits may appear on the retina.

The majority of patients do not develop vision loss except for a gradual blurring of vision that may not be noticeable. In some patients, blood vessels leak at the macula, which is the part of the retina responsible for central vision, thus causing loss of vision.

Proliferative retinopathy develops from background retinopathy and is responsible for most of the visual loss in diabetic patients.

New blood vessels grow (proliferate) on the surface of the retina and optic nerve.

These vessels tend to rupture and bleed into the vitreous cavity, or scar tissues may grow from the ruptured blood vessels that will contract and pull on the retina, thus detaching it and resulting in loss of vision.

Treatment for diabetic retinopathy

“Successful treatment of diabetic retinopathy depends on early detection and treatment,” said Dr Yeo.

If diabetic retinopathy is detected early, photocoagulation by laser treatment may stop it from getting worse. In cases where the disease is in an advanced stage, it can reduce the chance of the patient suffering severe loss of vision.

This treatment involves the use of laser beams to seal the abnormal leaking blood vessels and form tiny scars on the retina. These scars reduce new vessel growth and cause existing ones to shrink and close up. This treatment can be done on an outpatient basis.

Advanced cases of diabetic retinopathy are treated by a procedure called vitrectomy to remove blood from the centre of the eye (vitreous) and scar tissues that are tugging on the retina. Often, vitrectomy is accompanied by laser treatment. This procedure is done under local or general anaesthesia.

Prevention is better than cure

Preventable eye conditions such as diabetic retinopathy can be detected early and properly treated. “This is why there are active programmes to screen for these eye diseases. We recommend patients who are diabetic to go for diabetic retinal photography or retinal assessment so that if anything, they can be treated early and hopefully save their eyesight,” said Dr Yeo.

Fortunately for Mr Syed Mustaffa B Syed Hassan, who has been diabetic for more than ten years and is a patient of Dr Yeo, his diabetic retinopathy was picked up early and he had it successfully treated.

Like most cases, he was not aware of it, and it was when he underwent surgery for a hand injury three years ago that the doctor noticed blood clots in his eyes.

Mr Mustaffa was referred to SNEC where he was subsequently operated on, one eye at a time.

“Now I can see the bus numbers, watch TV and read!” said Mr Mustaffa.

Dr Yeo’s advice for diabetic patients is to control their diabetes with diet and medication to delay or prevent the development of diabetic retinopathy and other complications. In addition, they should also go for yearly eye examination.

Singapore National Eye Centre is an institution of SingHealth, the largest integrated healthcare group in Singapore.