Pigmentary glaucoma and pigment dispersion syndrome: causes, tests and treatment

Glaucoma is a group of eye conditions in which the optic nerve, the cable that connects the eye to the brain, becomes damaged. It is often, though not always, linked to raised pressure inside the eye. NICE Clinical Knowledge Summaries classify glaucoma by age of onset, cause, speed of onset and whether the drainage angle is open or closed.

Pigmentary glaucoma is a secondary form, meaning there is an identifiable cause. The cause is pigment dispersion syndrome. NICE CKS describes secondary open-angle glaucoma as uncommon, with a number of possible causes, and pigment dispersion is one of them.

Glaucoma UK describes the mechanism in plain terms. The iris is the coloured part of the eye. When it moves to adjust to changes in light it sometimes touches the lens and tiny coloured granules rub off. A few granules are normal and drain away with the fluid that fills the eye. In pigment dispersion syndrome more granules than usual are released, and they can settle on the iris, on the inner surface of the cornea and in the trabecular meshwork, the eye’s drainage channels.

Glaucoma UK explains that pigment can stick in and block the trabecular meshwork. The meshwork then works less well, the fluid called aqueous builds up inside the eye and the pressure rises. Because the drainage angle itself is open as it should be, this is called open angle glaucoma. Pigment dispersion syndrome and pseudoexfoliation are described as two common causes of long-term open angle glaucoma.

The charity is clear that having pigment dispersion syndrome does not mean you will have glaucoma. Many people have the pigment changes without ever developing raised pressure or nerve damage, which is why regular checks are the main safeguard for those who are known to have the condition.

The NHS notes that glaucoma does not usually have symptoms, develops slowly over many years and is usually found during routine eye tests. Glaucoma UK adds that vision loss usually starts in the side (peripheral) vision while central vision stays clear for much longer, and that the other eye can compensate so that gaps go unnoticed.

Sudden symptoms are different. The NHS lists intense eye pain, a red eye, tenderness around the eye, seeing rainbow-coloured rings around lights, blurred vision, feeling sick and headache as signs of glaucoma that can develop suddenly, and says to call 999 or go to A&E if they appear suddenly. This is more typical of angle closure than of pigmentary glaucoma, but it is an emergency whatever the cause.

Glaucoma is usually first suspected at a community optician. The NHS says everyone should have regular eye tests, at least every 2 years, and that people at higher risk may be advised to have them more often. If glaucoma is suspected you are referred to an ophthalmologist.

Glaucoma UK lists the tests: visual acuity, tonometry to measure eye pressure, a visual field test to map any patches of lost vision, and scans or photographs of the optic disc. Others may be needed, including a measurement of corneal thickness to help interpret pressure readings and gonioscopy to look at the drainage angle. The eye specialist can see features of pigment dispersion, and will tell you what type of glaucoma you have and how much vision loss, if any, is present.

Sometimes the results are borderline. The specialist may repeat tests and describe you as having suspected glaucoma, with regular monitoring in hospital or in a community setting such as a high street optician.

Treatment aims to lower eye pressure to slow future vision loss. The NHS lists eye drops, laser treatment and surgery, and Glaucoma UK explains that the choice depends on your test results, other health conditions and your preferences.

Glaucoma UK stresses that most people with glaucoma keep good vision for life, and that people who do lose significant vision are most often those who were diagnosed late or had other eye or health conditions. Using any prescribed drops every day and going to every appointment are the most important things within your control.

The charity says most people with glaucoma meet the minimum vision standards for driving, but that you may need to tell the DVLA (or DVA in Northern Ireland) depending on your circumstances, and it suggests checking with your motor insurer. The NHS points people towards Glaucoma UK and RNIB for support, including groups and helplines.

Because glaucoma can run in families, close relatives may want to have their eyes checked. The NHS notes that having a brother, sister or parent with glaucoma increases the risk.

Long-term glaucoma care in the UK is usually provided through NHS hospital eye clinics, often with some monitoring delivered by optometrists in the community. Eye drops are prescribed and the specialist team reviews pressure, visual fields and optic nerve scans over time.

Private eye clinics and opticians offer similar tests and some people use them for a quicker appointment or a second opinion. It is worth making sure any private results are sent to the team that is managing your glaucoma so that comparisons are made like for like.