Glaucoma

Glaucoma is a group of eye diseases that damage the optic nerve, the "cable" that carries pictures from your eye to your brain. Once nerve fibres are damaged, they do not grow back, so the vision lost from glaucoma is permanent.

Glaucoma is often linked to high pressure inside the eye. Your eye is always making a clear fluid, and the fluid drains out through a tiny drain at the front of the eye. If the drain does not work well, the pressure can build up and press on the optic nerve. Some people get glaucoma even with normal eye pressure.

Image to add

Simple diagram of the eye showing fluid flowing out through the drainage angle, and the optic nerve at the back. Alt text: "Diagram of the eye showing where fluid drains out at the front of the eye and where the optic nerve leaves the back of the eye."

The main types

• Open-angle glaucoma: the drain slowly becomes less efficient over many years. It is painless and has no early symptoms. Side vision is lost first.
• Angle-closure glaucoma: the coloured part of the eye (iris) blocks the drain. This can happen slowly, or suddenly as an emergency ("acute attack"). It is more common in people of East and Southeast Asian descent.
• Other types: glaucoma with normal eye pressure, glaucoma caused by other problems (eye injury, long-term steroid use, advanced diabetic eye disease), and rare glaucoma in babies and children.

What causes it?

The optic nerve is damaged, most often because the pressure inside the eye is too high for that nerve to cope with. Why this happens is not fully understood. Age, genes (it runs in families), the shape of your eye, and other health conditions all play a part.

Anyone can get glaucoma, but your risk is higher if:

• you are over 40
• a parent, brother or sister has glaucoma
• you have high eye pressure
• you are of Asian or African descent
• you are very short-sighted (open-angle) or long-sighted (angle-closure)
• you have diabetes
• you use steroid medicines for a long time (eye drops, tablets, inhalers or creams)
• you have had an eye injury or eye surgery before

Closer to home: in a large study of Malay adults aged 40 to 80 in Singapore, about 3 in 100 had glaucoma, and more than 9 in 10 of them did not know they had it.

Open-angle glaucoma has no symptoms in the early stages. You will not feel pain, and your central vision stays clear until late. The only way to catch it early is an eye check.

Acute angle-closure glaucoma is an emergency. Go to the Emergency Department immediately if you suddenly have:

What happens at a glaucoma check? All of these tests are painless:

• Eye pressure test (tonometry)
• Optic nerve check, looking at the back of the eye
• Visual field test, which maps your side vision; you press a button when you see a light
• OCT scan, a photo-like scan that measures the nerve fibre layer
• Gonioscopy, where the doctor uses a special lens to look at the eye's drain

What can happen?

Glaucoma slowly takes away your side (peripheral) vision first. Many people do not notice until a lot of vision is gone. Without treatment it can lead to:

• Tunnel vision, like looking through a pipe
• Bumping into things, falls, and accidents on the road
• Not being safe to drive
• Permanent blindness

Treatment aims to lower the eye pressure so the optic nerve is protected. It cannot bring back vision that is already lost, but it can stop or slow down further damage. Large studies have shown that lowering eye pressure slows glaucoma from getting worse.

1. Eye drops: the most common treatment. They must be used every day, for life, even when your eyes feel fine.
2. Laser treatment:
   • Selective laser trabeculoplasty (SLT) helps the drain work better in open-angle glaucoma. It can be a first treatment instead of drops for some people.
   • Laser iridotomy makes a tiny opening in the iris to relieve or prevent angle closure.
3. Surgery: creates a new drainage channel (trabeculectomy), or places a small drainage tube or device. For some people with angle closure, removing the natural lens (like cataract surgery) helps open the drain.

Fasting in Ramadan? Do not stop your glaucoma drops on your own. Talk to your eye doctor about the best timing for your drops, and refer to guidance from the religious authorities if you are unsure.

There is no sure way to prevent glaucoma, but you can prevent blindness from it by catching it early:

• Have an eye check if you are over 40, and regularly after that as advised.
• If someone in your family has glaucoma, tell your siblings and children to get their eyes checked.
• If you have glaucoma, use your drops every day and never miss follow-up appointments.
• Do not use steroid eye drops unless a doctor prescribed them and is checking your eyes.
• Protect your eyes with goggles during sports, DIY and work with tools.
• Stay active and keep diabetes and blood pressure under control.

Local updates and research

• Glaucoma is often hidden: in the Singapore Malay Eye Study, more than 90% of people with glaucoma had never been diagnosed. [6]
• Worldwide: the number of people with glaucoma was projected to reach about 112 million by 2040, with the largest numbers in Asia. [5]