What Is Glaucoma?
Glaucoma is a group of eye conditions characterised by progressive damage to the optic nerve — the nerve connecting the eye to the brain. In many forms of glaucoma, this damage is associated with elevated intraocular pressure (IOP), though normal-tension glaucoma can occur even when eye pressure is within the normal range.
Glaucoma is one of the leading causes of irreversible vision loss worldwide. Damage to the optic nerve that occurs with glaucoma cannot currently be reversed, making early detection critical.
Why Is Glaucoma Called the Silent Thief of Sight?
In the most common forms of glaucoma (particularly open-angle glaucoma), vision loss typically begins at the periphery (sides) of the visual field. Because central vision is often preserved until later stages, many people do not notice any change in their everyday vision for years.
By the time a person notices significant vision loss from glaucoma, considerable irreversible damage may already have occurred. This is why regular eye examinations — which can detect elevated eye pressure and optic nerve changes before noticeable symptoms develop — are so important.
What Happens to Vision in Glaucoma?
Glaucoma causes gradual loss of the peripheral (side) visual field. In the early stages, this may go unnoticed because the brain compensates for missing information. As glaucoma advances, the visual field constricts progressively, potentially leading to tunnel vision and, in severe untreated cases, complete vision loss.
Who Is at Risk of Glaucoma?
- People over 60 (risk increases with age)
- Those with a family history of glaucoma
- Individuals with elevated intraocular pressure
- People with thin corneas
- Those with high myopia (short-sightedness) or high hyperopia (long-sightedness)
- People with diabetes or hypertension
- Those who have had previous eye injuries
- Long-term users of corticosteroid eye drops
How Is Glaucoma Detected?
Glaucoma is detected through a comprehensive eye examination that may include:
- Tonometry — measurement of intraocular pressure
- Ophthalmoscopy — examination of the optic nerve
- Visual field testing — to assess peripheral vision
- Optical coherence tomography (OCT) — imaging of the optic nerve and nerve fibre layer
- Pachymetry — measurement of corneal thickness
Because no single test is sufficient to diagnose glaucoma, a combination of assessments is typically used.
How Often Should You Have Your Eyes Checked for Glaucoma?
Most adults are recommended to have a comprehensive eye examination at least every one to two years. Those with risk factors for glaucoma may benefit from more frequent checks — your ophthalmologist will advise based on your individual situation.
People who have been diagnosed with glaucoma require regular ongoing monitoring to assess response to treatment and detect any progression.