Open-angle glaucoma: symptoms, tests, eye drops and living with it

Glaucoma is a group of eye conditions in which the optic nerve, which connects the eye to the brain, is damaged. RNIB explains that the eye needs a certain amount of pressure to stay healthy, but if the pressure is too high the optic nerve can be damaged at the point where it leaves the eye. It is also possible to develop glaucoma when eye pressure is within the normal range, perhaps because the nerve is more fragile than usual.

In primary open angle glaucoma (POAG), RNIB says damage to the optic nerve occurs slowly over a long period of time as eye pressure rises. The NHS describes the underlying problem as fluid in the eye not draining as it should, building up pressure that damages the optic nerve.

RNIB says blind spots begin to form and sight loss usually affects the side (peripheral) vision first, and that your vision can be gradually damaged without you being aware of it because peripheral vision is less sensitive than central vision. The NHS notes that most people do not realise they have glaucoma, and that it usually affects both eyes but may be worse in one.

Without treatment, RNIB lists difficulty seeing contrast, poor night vision, reduced side vision and, if untreated, loss of central vision and eventually blindness. Sudden glaucoma with intense eye pain, a red eye, rainbow-coloured circles around bright lights, blurred vision, nausea and headache is a different, emergency form. The NHS says to call 999 or go to A&E if you develop symptoms of glaucoma suddenly.

The NHS says glaucoma is usually caused by a build-up of pressure in the eye, though sometimes the pressure is in the normal range and damage still occurs. Your risk may be higher if you are over 50, have a brother, sister or parent with glaucoma, are from a Black African, Caribbean or Asian background, or have other medical conditions such as short-sightedness, long-sightedness or diabetes. The NHS says if you are at higher risk, for example if a sibling or parent has glaucoma, you may be advised to have eye tests more often.

The NHS says glaucoma is usually found at a routine eye test by an optometrist, and that if you are told you have it you should be referred to an ophthalmologist for further tests. Eye tests can be had at a local optician, and some people can receive free NHS sight tests. RNIB describes the main types: primary open angle glaucoma with eye pressure above 21 mmHg, normal tension glaucoma where damage occurs at pressures below 21 mmHg, and ocular hypertension, which is high eye pressure without damage.

Once referred, the ophthalmologist arranges the further tests needed to decide on treatment, and RNIB says your doctor will explain what the results mean for your sight.

The NHS says there is currently no cure, but there are treatments that can slow down the damage and help stop vision getting worse. The treatment you have depends on how your sight is affected and the type of glaucoma you have.

The NHS says that if glaucoma is diagnosed and treated early it may not change your vision much, but sometimes sight is affected and in rare cases you may lose your sight. For many people it means using eye drops daily and attending regular eye clinic appointments. RNIB says that if glaucoma is untreated or poorly controlled it can eventually lead to complete loss of sight, but that with treatment most people keep good vision for life.

Taking drops regularly and attending appointments are the most important things you can do, because damage cannot be reversed. Charities such as Glaucoma UK and RNIB offer information and support, and the NHS suggests your specialist eye doctor will advise on how it may affect your sight and how to live as independently as you can.

Routine testing is done by community optometrists, and diagnosed glaucoma is managed through hospital eye services or community glaucoma schemes. Private optometrists and ophthalmologists can offer eye tests and consultations, and many people use them for a quicker assessment or second opinion, but whichever route you use the key points are the same: take drops as prescribed and keep follow-up appointments. Always tell any eye clinician about your family history.