Glaucoma is the leading cause of blindness in New Zealand. It is a range of conditions that affect the optic nerve and cause blindness when not treated.

The risk of getting glaucoma increases with age. By 40 years old 2% of New Zealanders have glaucoma. By 80 years old 10% are affected by it. It’s not just age though; even children can also get glaucoma.

Glaucoma is usually the gradual increase in pressure inside the eye (though it can happen very quickly in some people). The pressure inside the eye is called intraocular pressure. If this pressure increases it can damage the optic nerve. This is the nerve that transmits images from your eyes to your brain. If glaucoma is not diagnosed and treated, the increasing pressure inside the eye leads to permanent loss of vision and eventually blindness. Some people can have normal-pressure glaucoma.

The eye is like a balloon. It needs some pressure inside it or it would collapse. Your eye constantly produces a fluid to keep the pressure in your eye that you need. This fluid then drains away; fluid in, fluid out, all the time to keep the pressure even. If the fluid cannot drain away the pressure builds up in your eye.

If the pressure gets too high, you will start to lose your eyesight due to pressure on your optic nerve. Often loss of sight starts at the edges of your vision and so sometimes people don’t notice it straight away. Glaucoma can be treated to stop it getting worse but it cannot be reversed once eye sight has been lost.

This is why it is so important to get regular check-ups for your eye pressure from when you turn 40 years old.

Different types of glaucoma
There are several different sorts of glaucoma. The most common are open angle and closed angle glaucoma.

Open angle glaucoma: is the most common. This is where the drainage channels become blocked or hardened. The fluid is produced in your eye but can’t drain away very well. Most people have no symptoms with this until they have lost a lot of their sight, so regular check-ups with an optometrist are essential.

Closed angle glaucoma: is when the angle at the edge of your eye prevents the fluid getting to where it can drain away. The pressure then builds up in the eye causing damage to the optic nerve. If this happens suddenly it is called ‘acute angle closure glaucoma’. This is very painful causing a red eye, severe headache and loss of vision. It is a medical emergency – go straight to the hospital.

Normal pressure glaucoma: In some people there is damage to the optic nerve even with normal pressure in the eye. Get regular eye check-ups.

Children can get glaucoma: Though it is rare it can happen after trauma or surgery to the eye. It may also be inherited or genetic.


  • Open angle glaucoma can usually be treated with eye drops. It is important that you use them every day exactly as you were told. Go back for your check-ups so the eye specialist can check that these eye drops are working for you. There are several choices of eye drops and no one medicine suits everyone. Once you have eye drops that work for you, these can usually be prescribed by your usual family doctor.
  • For closed angle glaucoma, when the gap looks like it will close over completely, there is a laser surgery called iridotomy that can make a tiny hole in the eye to allow the angle to become more open.

If you believe you or someone you love is losing peripheral (edge) vision. Get this checked by an optometrist urgently. There are treatments available to prevent any further loss of eyesight. Current treatments are not able to return any eyesight already lost.
