Diagnosis

Acute PACG is regarded as relatively straight-forward to diagnose as the sufferer is likely to have eye pain, often severe, and associated headache, nausea and vomiting. The eye is usually red and tender, the pupil semi-dilated and fixed (classically in a vertically oval shape), visual acuity is impaired and lights appear to have halos around them. When measured, IOP is typically very high, sometimes at or over 32mmHg.

In intermittent PACG, the symptoms are generally less severe and respond to measures such as lying down with eyes closed, resolving relatively quickly. Individuals experiencing this condition may report previous episodes of blurred vision, headaches or eye pain associated with nausea, typically occurring in the evening and relieved by sleeping. An eye examination will usually reveal raised IOP and narrow angles where the cornea and iris meet.

Chronic PACG is typically asymptomatic until visual field defects affect vision or are picked up during a routine eye examination. Optometry investigations are likely to also detect raised IOP, a cupped optic disc and signs of angle closure. PACG affects about 0.4 per cent of the UK’s over-40s, but prevalence increases with age.

Diagnoses of COAG and OHT are usually made during routine eye tests because individuals are asymptomatic. Visual field defects can be difficult for individuals to be aware of because the visual fields of each eye overlap, so one eye may compensate for a problem with the other. 

As well as picking up on visual field defects and raised IOP, optometry may also find a cupped optic disc. Patients with NTG will have an IOP within the acceptable range, but an eye examination will detect other issues, such as retinal thinning or bleeding around the optic nerve. Visual field defects may also be present, and NTG tends to affect central vision at an earlier stage than COAG.

The asymptomatic nature of COAG means that individuals who are at increased risk of the condition should have regular eye checks. Pharmacists and their teams have a role in highlighting the availability of free NHS glaucoma checks to anyone aged 60 years or over, people over 40 years of age with a first degree relative with COAG, and individuals who have been advised by an ophthalmologist that they are at increased risk of developing glaucoma. A full list of eligibility criteria for NHS sight tests is available on the NHS website.

To give a sense of how widespread COAG is, the condition affects around 1-2 per cent of over-40s in the UK, but prevalence increases with age. It is estimated that around 3 per cent of 60-year-olds and 4-5 per cent of 80-year-olds are affected. Around half of people with COAG in the UK are thought to have not been diagnosed. Ocular hypertension affects between 3-5 per cent of over-40s in this country.