Keep an eye out for glaucoma, which is on the rise in Singapore

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SINGAPORE - In late 2018, Mr Desmond Ho's vision suddenly started to blur.

The next year, he was diagnosed with early-stage glaucoma.

The 41-year-old mechanical engineer says: "It was affecting the quality of my life. I could not see the markings on the milk bottle while preparing milk for my son. I also could not see bus numbers and people's facial expressions unless I went very close to them."

Mr Ho was later found to have cataracts as well. In February this year, he underwent glaucoma and cataract surgery on his right eye.

One of the leading causes of blindness in Singapore, glaucoma is caused when high fluid pressure within the eye damages the optic nerve. This leads to the gradual loss of peripheral vision, followed by central vision and blindness.

An ageing population and greater awareness through public education have led to more people getting screened for the condition, resulting in an increase in cases, say doctors.

For example, the Singapore National Eye Centre (SNEC), which handles nearly 75 per cent of glaucoma patients here, has seen a 40 per cent increase in such patients from 2015 to 2019.

In Singapore, about 3 per cent of people above the age of 50 have glaucoma. This reaches almost 10 per cent for those above 70.

People with a family history of glaucoma, long-term steroid use or eye injury are also at higher risk.

A surprisingly frequent cause of eye trauma that may lead to glaucoma is being hit in the eye by a badminton shuttlecock, says Dr Yap Zhu Li, a consultant ophthalmologist at SNEC's glaucoma department. Such blunt trauma can damage structures in the eye.

"In the acute phase, this may manifest as bleeding within the eye or displacement of the lens, causing physical or mechanical blockage of the eye's drainage system.

"In the more chronic phase, direct damage sustained by the drainage system leads to its dysfunction and a rise in the fluid pressure in the eye."

People who have myopia or hyperopia (far-sightedness) are also at higher risk of getting glaucoma.

Associate Professor Victor Koh, head of and consultant at the National University Hospital's (NUH) Department of Ophthalmology, explains the link between high myopia and glaucoma.

"There is an elongation of the eyeball from front to back in eyes that are highly myopic. This mechanical stretching puts stress on the optic nerve and makes it susceptible to eye pressure changes, which lead to glaucoma."

People of Chinese ethnicity are more at risk of developing closed-angle glaucoma, which occurs when the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris.

A study released in 2018 by the Singapore Eye Research Institute and SNEC found that Chinese Singaporeans with moderate myopia of 300 to 600 degrees were five times more likely to have glaucoma than those without myopia.

Often referred to as a silent thief of sight, glaucoma is usually asymptomatic in the early stages.

Mr Ngo Teck Kim, a retired lift and elevator maintenance worker, found out he had glaucoma only when he went to NUH in 2007 for an eye irrigation procedure after sand got into his eyes while he was riding a motorbike.

His uncle and younger sister also have glaucoma.

Mr Ngo, 77, went for surgery on his right eye in 2008. After several years, the pressure in his right eye increased again, and he underwent surgery again in October last year. He also had glaucoma and cataract surgery on his left eye in 2018.

The optic nerve damage caused by glaucoma is irreversible. However, further vision loss and damage can be prevented by reducing the pressure in the eye.

Prof Koh says the reduction of pressure in the eye is the main form of treatment and can be done through the application of eye drops, laser, or going for surgery.

The general aim of surgery is to create alternative pathways for the fluid inside the eye to flow out to reduce the eye pressure, he adds.

Dr Jayant Venkatramani Iyer, a consultant with the Department of Ophthalmology with SNEC Eye Clinic at Changi General Hospital, says glaucoma is a chronic condition that needs lifelong monitoring to ensure that the pressure is controlled to a level that preserves the optic nerve and vision.

He advises people with sudden eye pain, redness in the eye, blurred vision, one-sided headache with nausea or vomiting to go to the hospital or consult an eye specialist immediately to screen for acute closed-angle glaucoma - a potentially blinding condition.

Prof Koh says people above 40 should get checked for glaucoma and other age-related eye diseases such as cataracts and macular degeneration.

Those who have risk factors related to glaucoma should go for screenings earlier, he adds.

Referring to glaucoma, he says: "If the condition is detected early and treated, there is a very good chance of preserving vision and quality of life."

 

Difference between glaucoma and cataracts

A cataract is an eye disease in which the clear lens of the eye becomes cloudy or opaque, causing a decrease in vision.

Glaucoma, on the other hand, is a condition where a build-up of pressure in the eye damages the optic nerve - an important link of the eye to the brain, which processes visual information.

Both conditions can occur at the same time, and this happens more frequently in older people, says Dr Yap Zhu Li, a consultant ophthalmologist at the Singapore National Eye Centre's glaucoma department.

Symptoms of a cataract include progressive blurry vision, poor night vision, double vision, fading of colours and frequent changes to eyewear prescription.

Dr Yap notes that people usually develop cataracts from the age of 50.

However, there are other conditions which may cause a cataract to occur earlier, such as diabetes, chronic steroid use, inflammatory eye disease, high myopia, eye trauma or smoking.

While a cataract and glaucoma are different diseases affecting different parts of the eye, Dr Yap says there is some link between the two.

"Cataracts do not cause glaucoma per se, although there are some situations where the cataract causes high eye pressure and damage to the optic nerve.

"As the cataract gets thicker and more mature, it can contribute to the mechanical blockage of the eye's drainage angle by making it more narrow, thereby restricting normal fluid outflow, causing secondary closed-angle glaucoma."

Associate Professor Victor Koh, head of and consultant at the National University Hospital's Department of Ophthalmology, says glaucoma sufferers who have undergone surgery for their condition may be predisposed to cataract formation due to prolonged inflammation and the use of steroid eye drops.

 

6 myths about glaucoma

Dr Katherine Lun, an associate consultant at National University Hospital's department of ophthalmology, clears up six misconceptions about glaucoma.

 

1. I do not have a family history of glaucoma and hence I will not get glaucoma.

While having a family history of glaucoma puts you at higher risk of developing the condition, the absence of a positive family history does not exclude you from developing it. There are many patients with no family history of it.

 

2. I can see very well and have no eye pain. I am sure I do not have glaucoma.

Most patients with glaucoma are of the open-angle subset and do not have symptoms in the early stages as glaucoma typically affects peripheral vision first.

By the time vision loss is detected, the patient likely has moderate to severe glaucoma. This is why glaucoma is termed the "silent thief of vision".

In patients with closed-angle glaucoma, a small portion of them may present with sudden eye pain and blurred vision, headache, nausea and vomiting, signifying a sudden rise in eye pressure and requiring emergency treatment to lower it.

These patients tend to have earlier symptoms compared with those with open-angle glaucoma.

 

3. I was recently told that I have glaucoma. Will I go blind?

Although glaucoma is a potentially blinding disease, the risk of blindness can be greatly reduced with early diagnosis and treatment.

Not all patients go blind from the disease and many continue to lead independent and fulfilling lives.

It is important that you are compliant with the prescribed medications and go for regular eye checks.

Compliance with medications will ensure that the eye pressure is controlled, and this in turn helps to prevent vision loss.

If the eye pressure is not controlled, your doctor may choose to add or switch medications.

If medications fail, you may need to undergo laser or glaucoma surgery.

 

4. My doctor started me on glaucoma eye drops. Why is my vision still blur?

Unfortunately, there is no treatment that can cure glaucoma.

The damage that glaucoma does to the eye nerve and the vision that is lost as a result is irreversible.

After starting on glaucoma eye drops, the focus should be on controlling the eye pressure to prevent further vision loss and blindness.

 

5. Glaucoma is a disease of the elderly. I am young and healthy and it is not possible for me to develop this condition.

It is true that most patients with glaucoma are older than 50. However, there are young adults and children who develop this condition as well. Many are diagnosed when they seek an eye review for other non-related eye conditions.

 

6. Why does my doctor keep asking me to do eye tests? Is eye pressure not the only thing that needs to be checked?

Glaucoma is a condition that affects the eye nerve, leading to vision and visual field loss if left untreated.

To monitor the disease progression, it is important to do regular and comprehensive investigations such as visual field tests and eye nerve tests, on top of vision check and eye pressure measurements.

 

Source: The Straits Times © Singapore Press Holdings Limited. Reproduced with permission.

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