Most people assume glaucoma is about high eye pressure. It is one of the most persistent misconceptions in eye health — and for patients with normal tension glaucoma, it can mean years of undetected damage before the right diagnosis is made.
What is normal tension glaucoma?
Normal tension glaucoma is a form of open-angle glaucoma in which the optic nerve sustains progressive damage despite intraocular pressure (IOP) sitting within what is considered the normal range — typically below 21 mmHg. It accounts for a significant proportion of glaucoma cases in the UK, yet it is frequently missed at routine optician appointments precisely because pressure checks come back unremarkable.
The damage to the optic nerve is real, and it is progressive. Without specialist intervention, patients with normal tension glaucoma can lose significant peripheral vision before they are aware anything is wrong.
Why is it so often missed?
Standard community eye tests are not designed to detect normal tension glaucoma. A tonometry reading within normal range tends to close the investigation. What is needed is a detailed assessment of the optic nerve head itself — using OCT imaging to measure nerve fibre layer thickness, paired with visual field testing to map any areas of vision loss. These are the tools of a specialist glaucoma clinic, not a high street optician.
Patients are often referred to LondonOC only after a routine OCT scan at their optician flags a suspicious disc appearance — sometimes years after damage has begun.
Who is at higher risk?
Normal tension glaucoma is more prevalent in people of East Asian heritage, those with a family history of the condition, patients with low blood pressure or a history of cardiovascular disease, and individuals who have experienced a significant blood pressure drop overnight. If any of these apply to you, it is worth discussing a specialist assessment even if your IOP has always been reported as normal.
What does treatment involve?
The goal is to reduce IOP below whatever level is contributing to nerve damage — even within the so-called normal range. Treatment may include pressure-lowering drops, laser therapy, or surgical intervention depending on severity. At LondonOC, management is tailored to each patient's pressure profile, nerve health, and systemic risk factors, with regular monitoring to track stability over time.
If you have been told your eye pressure is normal but you are concerned about your optic nerve or family history, a specialist opinion is the right next step.