Glaucoma damages the optic nerve, typically in the context of raised intraocular pressure. The fibres that die first are the ones serving peripheral vision, and they die slowly and painlessly. Patients do not notice because the brain fills in the gaps from the other eye and from memory. By the time central vision is threatened, a large proportion of the nerve may already be gone.
Intraocular pressure is a risk factor, not a diagnosis. Some people develop glaucoma at pressures considered normal, and many people with high pressure never develop it. That is why assessment involves the optic disc — imaged and compared over time — and visual field testing, which maps where you can actually see.
Perimetry asks you to respond to lights appearing at various points in your peripheral vision. A single field test is noisy: everyone has bad days, and the test has real variability. What matters is the trend across several tests over years. A slow decline is the signal, and it can only be seen if testing happens consistently.
Nerve fibres that have died do not regenerate. Every treatment for glaucoma is aimed at slowing further loss. This is why the disease is monitored for decades rather than treated once, and why missing appointments is the most common way patients lose vision they did not have to lose.
Prostaglandin analogue drops are usually first-line, reducing pressure by improving outflow. Laser trabeculoplasty is an increasingly common alternative or addition. Where drops and laser are insufficient, filtration surgery creates a new drainage pathway. Each step has trade-offs and we discuss them rather than prescribe them.
Anyone over 40 should have a baseline assessment, and earlier if there is a family history. African ancestry, high myopia, diabetes and long-term steroid use all raise risk. If a parent has glaucoma, you should be assessed well before you have symptoms, because by definition symptoms arrive late.
This article is general information about eye conditions and does not replace an examination. If you have symptoms, book an assessment.
Book an assessment →