In the UK, glaucoma affects about 2% of people over the age of 40 and 5% over the age of 75. It is a group of diseases affecting the health of the optic nerve – the structure which relays sight information from the eye to the brain. Sight loss is often gradual, from the periphery inwards and without other symptoms, so consequently not easily noticed early on. If undiagnosed, in its advanced stages it leads to tunnel vision (see picture below) and ultimately blindness.
Glaucoma is often, but not always, associated with raised internal eye pressure, which is why we perform a pressure test on all adults in the course of an eye examination. A visual field test can give an early indication of glaucoma and is also included in the eye examination for all adults. In addition, the optometrist will use an ophthalmoscope to inspect the appearance of the optic disc, where the optic nerve joins the back of the eye, as this can also indicate the presence of glaucoma.
In most cases glaucoma develops slowly over several years – known as ‘chronic’ glaucoma – and usually responds well to treatment (in the form of daily eye drops) if caught soon enough. Having a regular eye examination (at least every two years) is therefore the best safeguard in this respect – those with a family history of glaucoma are encouraged to have an annual eye examination as they are at a higher risk of developing the disease.
‘Acute’ glaucoma is fortunately much rarer than the chronic variety, and is a sudden increase in eye pressure – often resulting in eye pain, severe headache, nausea, vomiting, blurred vision and haloes or a rainbow effect around bright lights. It can cause damage to the cornea, the lens, the iris and the optic nerve. Patients with these symptoms should seek immediate ophthalmological attention at hospital.
The infographic on the right of this page is supplied courtesy of the Association of British Dispensing Opticians.
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