Glaucoma explained, and why regular eye checks are vital for the over-40s

Newly diagnosed glaucoma sufferers are often shocked upon learning their failing eyesight cannot be restored to their original acuity, that there is no cure. If unchecked, victims can go blind.

Glaucoma is a group of eye diseases associated with the degeneration of the optic nerve that carries information from the eyes to the brain. This leading cause of irreversible blindness in the city affects three per cent of Hongkongers aged 40 or over, according to the Hospital Authority.

The chronic kind, “primary open angle glaucoma,” is most common and often asymptomatic. Victims may not notice their vision is eroding until much of it has gone.

“More than half of their visual field has been lost before they notice something abnormal [and see the doctor], that’s why glaucoma is scary,” says Clement CY Tham, chairman of the department of ophthalmology and visual sciences at Chinese University of Hong Kong and director of the CUHK Eye Centre.

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Inside a healthy eye is a “rim” full of neural tissue; in a patient with glaucoma, that “rim” has thinned, disrupting the vision process. The cause is not fully understood.

“Even in normal people, you lose optic fibres everyday as part of the ageing process, but in glaucoma patients, the loss happens at a far higher rate than the average person,” says Tham.