Glaucoma

Glaucoma damages the optic nerve, usually without pain. Side vision goes first, so most people notice nothing until a lot is lost. Treatment exists to stop that loss.

A close-up of a blue eye — Photograph: Ion Fet, Unsplash

Sight lost to glaucoma cannot be brought back.

Treatment can stop it getting worse.

A check after forty finds it early, and is the best protection.

Why it is called silent

The optic nerve carries the picture from the eye to the brain. In glaucoma it is slowly damaged, most often because the pressure in the eye is too high for it. The edges of your vision close in, so slowly that the brain fills the gaps.

It has no pain, redness or warning in its common form.
Age over forty, a family history, diabetes, high short-sight and steroid use raise the risk.
In a rare, sudden form, the eye becomes painful and red with blurred vision, and needs treatment at once.

How it is found

1
Eye pressure
Measured with an applanation tonometer fitted to the slit lamp, the standard test.
2
The optic nerve
Examined under the slit lamp, for the cup that glaucoma enlarges.
3
An OCT scan
Measures the thickness of the nerve fibre layer, which thins before sight is lost.