The silent thief of sight
Glaucoma is a group of diseases that cause damage to the optic nerve, which transmits information from your retina to your brain. Glaucoma is usually the result of pressure caused by build-up of aqueous fluid in the eye. As it increases, this pressure damages the optic nerve.
Glaucoma is often called “the silent thief of sight” because it can develop for years before people notice any symptoms – and by then, they may already have permanent vision loss. Glaucoma can affect one or both eyes, and the severity of vision loss depends on where the damage happens.
Types of glaucoma
There are four types of glaucoma:
Primary open-angle glaucoma: This is the most common type, affecting 90% of people who have glaucoma. When the eye produces too much aqueous fluid, or when the fluid doesn’t drain properly, pressure can build up and damage the optic nerve. This leads to loss of peripheral vision. If the glaucoma isn’t treated, vision may keep narrowing (“central vision” or “tunnel vision”) or be lost entirely.
Closed-angle glaucoma: This type of glaucoma can occur when aqueous fluid in the eye can’t drain normally. As we get older, the “drainage angle” between the iris and the cornea can become narrower. If the angle closes or is blocked, fluid can’t reach the eye’s drainage system. Closed-angle glaucoma (also referred to as narrow-angle glaucoma or angle closure glaucoma) can happen gradually or suddenly. It is a medical emergency that requires immediate treatment.
Secondary glaucoma: This type results from another problem, such as an injury, an infection, inflammation or a tumour in or near the eye; a medical condition (such as diabetes) or certain medications; or complications from eye surgery.
Normal-tension glaucoma: This type of glaucoma is not caused by changes in pressure, yet the optic nerve suffers damage.
Who is at risk of developing glaucoma?
The risk factors of glaucoma include:
- Age over 60, or over 40 for people with African heritage
- Family history of glaucoma
- African, Hispanic or Asian heritage
- High eye pressure
- Farsightedness or nearsightedness
- Eye injury
- Long-term use of corticosteroid medications
- Certain characteristics of eye anatomy, such as thin corneas, a thinning optic nerve, optic nerve sensitivity
- Eye conditions such as retinal detachment, inflammation or a tumour
- Diabetes, high blood pressure, heart disease, migraines
Taking care of your vision
If you notice anything unusual about your eyesight – such as blurred or decreased vision, vision loss, pain or redness, or seeing halos around lights – it’s important to get a comprehensive eye exam.
Regular check-ups can help you catch any problems early. To maintain healthy vision, it is recommended that eye examinations be carried out every two years for people aged six to 64, and at least once a year for people 65 and older. Older adults are at greater risk of developing not only glaucoma, but other eye conditions including dry eyes, presbyopia, cataracts, macular degeneration and diabetic retinopathy.
How is glaucoma treated?
Glaucoma is treated by reducing the pressure in the eye, and this could involve oral medications, eye drops or surgery. There is not yet a cure for glaucoma, but these interventions can slow or prevent vision loss.