Glaucoma: the test that finds it years early

What it is

Damage to the optic nerve — the cable from eye to brain — usually because the pressure inside the eye is a little too high for that nerve. It takes the edges of your vision first, so slowly and so symmetrically that the brain fills in the gaps. People with advanced glaucoma often think their sight is fine. Treated early, with drops, it’s controlled for life; the damage already done is permanent.

Who’s at risk

Anyone over forty, and the risk rises with age. A parent, brother, sister or child with glaucoma roughly quadruples yours — and gets you a free NHS test from forty. Short sight, diabetes, African or Caribbean heritage, and long steroid use all raise it.

The three checks

Pressure — the puff of air, or a gentler probe. High pressure is a risk, not a diagnosis; plenty of glaucoma happens at normal pressure. The optic nerve, looked at and photographed: a nerve being damaged changes shape. The OCT scan — this is the early one. It measures the thickness of the nerve-fibre layer around the nerve to a hundredth of a millimetre, and thinning shows up years before the field of vision changes or the nerve looks different. On every Gold and Platinum examination; £25 on an NHS test. Visual fields — the peripheral-vision test — when the others raise a flag.

What happens if something’s found

We repeat and compare; one scan is a snapshot, two are a trend. If it’s glaucoma or the risk is real, we refer to the hospital eye service, which starts drops, and we share the monitoring after that. The point of finding it at forty-five rather than sixty is that you keep the sight you have.

The short version

• No symptoms until sight is lost — it’s found at tests
• Over 40, and a close relative with it: free NHS test, yearly
• The OCT nerve-fibre scan finds it years earliest
• Found early, it’s controlled for life

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