Primary open angle glaucoma

This is the most common form of glaucoma and usually develops slowly over a course of a few years when high pressure in the eye causes damage to the optic nerve.

Causes of primary open angle glaucoma

The angle of the eye is where the natural fluid inside the eye drains out of the eye in a healthy eye. In open angle glaucoma, although the angle is visible (i.e. ‘open’) the channels in the angle has malfunctioned and do not allow fluid flow out of the eye freely, causing the pressure inside the eye to become elevated and squashing the optic nerve and thereby damaging it.

Who is at risk of primary open angle glaucoma?
Age & Ethnicity

This condition usually affects people over age of 40 and the risks increases as one gets older. However, in people of African origin, this condition and developed at a much younger age (see below). In general, the risk primary open angle glaucoma is four times greater than people of European origin at any age group. Amongst European population, the incidence is around 1% for the over 40 and increases to 5% of those over 80.

Family History

If you have primary open angle glaucoma, your siblings and children have at least a four-fold increased chance of developing the condition. You should advise members of your family to have regular eye check-ups by your optician.

Primary open angle glaucoma

It is unusual to have symptoms when patient developed primary open angle glaucoma, as the eye pressure rises very slowly and there is no pain, even though the optic nerve is being damaged. For this reason, damage often has already occurred before the person with glaucoma realises there is a problem.

It is important to diagnose and start treating glaucoma early on, before it has advanced to a stage where there has been extensive irreversible sight loss.


The eye specialist will carry out a range of tests in order to see how much damage has been done. These will include a visual examination of the nerve of sight where it leaves the eye (the optic disc), a check of the pressure in the eye (the intraocular pressure) and a test to map out any blank or missing patches that may be found in the vision (visual field test). Other tests may include measuring the central corneal thickness (pachymetry) and looking at the drainage angle in the eye (gonioscopy), and OCT scan of the optic nerve to confirm the diagnosis.


Primary open angle glaucoma is usually treated with laser (SLT) or eye drops that reduce the pressure in the eye. If you are using drops, it is imperative to take your eye drops every day according to the instructions. If the eye drops or laser can’t control the pressure enough to stop the glaucoma getting worse, then different drops or surgery may be recommended. Glaucoma is a lifelong condition – there is no cure, but treatment is very effective.
For someone diagnosed with early stage primary open angle glaucoma today, there is very little risk of losing useful vision providing you take your drops regularly and don’t miss your follow up appointments.