Open angle glaucoma

Specialty of Optometry

What is open-angle glaucoma?

Open-angle glaucoma is one of the most common types of glaucoma. Glaucoma is a condition that causes damage to the optic nerves of the eyes, which becomes worse over time and if it continues to worsen, can lead to permanent vision loss.

It comes on slowly and painlessly and patients can go for years without noticing that they have it. This is because the initial loss of vision is of the side, or of the peripheral vision, whilst general vision is maintained until late into the disease. Open-angle glaucoma tends to occur in people over the age of 50 and generally has no symptoms in the early stages.
 

What causes open-angle glaucoma?

The eye produces a fluid (aqueous humour), which keeps it healthy and maintains its pressurised state. As new fluid continually comes in the old has to drain out of the trabecular meshwork, which is a network of cells that sits in an area called the drainage angle. This “open-angle” is where the clear part of the eye (cornea) meets the coloured part (iris) and wraps 360 degrees around the circumference of the front part of the eye.

As we age, the trabecular meshwork does not function as well, which affects the flow of the fluid into and out of the eye, and the level of pressure can rise over time. The elevated eye pressure causes damage to the optic nerve cells, which leads to permanent vision loss.
 

How is open-angle glaucoma tested for?

The eye specialist will numb the eyes with a drop. The doctor checks the eye pressure, looks for an open angle and measures the thickness of the cornea. The patient may also have a dilated eye exam, where the doctor can put a drop on the pupil to make it open wide and to check on the optic nerve health.
 

How is open-angle glaucoma treated?

The damage to the optic nerve and to vision cannot be fixed but the progression of glaucoma can be slowed down. This is achieved by lowering eye pressure, even if it seems normal. The patient will be provided with eye drops for glaucoma. If these do not work then there is laser therapy, which helps the eyes to drain better. The last resort is surgery with either of the following procedures:

  • Drainage tubes – the surgeon places tiny tubes into the eyes that drain fluid into a small device.
  • Filtering surgery – the doctor makes a small hole in the eye, which allows fluid to drain out.
  • Minimally invasive glaucoma surgery – this requires tiny openings and uses devices that are invisible to the naked eye.
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