What is glaucoma?

Glaucoma is not a single disease - rather, it is caused by a group of eye conditions that damage the optic nerve. The optic nerve contains approximately one million nerve fibres, and it carries visual information from the eye to the brain. As glaucoma damages these fibres, vision is slowly lost.

Glaucoma is present in 3% of the population. It is more common with advancing age, and in women, with the prevalence increasing by around 10% per year of age after age 50. Nearly half of those people with glaucoma do not know they have the disease.

In most cases the pressure within the eye is increased, with elevated intraocular pressure being the most important risk factor for developing glaucoma. In these eyes the pressure is too high for the optic nerve cells to tolerate, and they subsequently die. If enough of the cells die, some or all of the vision may be lost.

Broadly speaking there are a three different types of glaucoma;

1) Open Angle Glaucoma.
This is the most common form of glaucoma in Western populations and is caused by the trabecular meshwork becoming silted up.

2) Chronic Closed Angle Glaucoma.
This is caused by blocked drainage through a narrow angle between the iris and the cornea with resultant scarring of the trabecular meshwork. It is more common in Asian and Chinese populations.

3) Acute Angle Closure Glaucoma (AACG).
In this condition forward movement of the iris to cover the trabecular meshwork, will result in a sudden and painful increase in the intraocular pressure.

However, glaucoma is not simply a case of "high eye pressure" diagnosed by measuring the pressure in your eye. Ninety percent (90%) of people with elevated pressure (Ocular Hypertension) do not have glaucoma, and up to one third of those with glaucoma have a "normal" eye pressure.

Glaucoma is called the "silent thief of sight" because it develops without obvious symptoms. Therefore, the person with glaucoma is usually unaware they have glaucoma until serious loss of vision has occurred. In fact, half of those suffering damage from glaucoma are unaware they have the disease. As the damage from glaucoma cannot be reversed, early detection, diagnosis, and treatment by your eye doctor (ophthalmologist) is vital to preserve your vision.