Glaucoma is the name given to a group of eye diseases often associated with too much pressure inside one or both eyeballs. It is a leading cause of damage to vision or blindness in people over 40 but can affect people of any age. If glaucoma is detected early, treatment can prevent or reduce loss of vision in most patients. The aqueous humour is a clear, watery fluid produced by the ciliary body. Its role is to nourish the lens and cornea. It drains out of the eye through a sieve like structure - the trabecular meshwork (as shown in the figure). Glaucoma occurs when the amount of aqueous fluid pumped into the eye by the ciliary body is greater than the fluid flowing out of the eye through the trabecular meshwork. This imbalance increases the pressure, also called intraocular pressure.
This increase in intraocular pressure results in damage to the delicate fibres of the optic nerve that connects the eye to the brain. This damage is permanent. The aim of treatment is to decrease fluid production or to increase fluid drainage.
This is the most common type of glaucoma. As the condition is usually painless and without symptoms, it can slowly damage the eye without the person being aware it is present. In open-angle glaucoma, the aqueous fluid cannot flow through the trabecular meshwork and drain properly, causing the pressure in the eye to rise and eventually damage the optic nerve.
Angle-closure glaucoma usually causes sudden, severe pain in the eye, often with immediate disturbance of vision, such as coloured rings around lights. The patient may have nausea and vomiting. Damage to the optic nerve can occur within hours. Emergency treatment (usually medication and laser) is needed to prevent partial or complete loss of vision.
Some images and information provided courtesy of RANZCO and Mi-tec Medical Publishing. The complete RANZCO patient education pamphlet is available from your ophthalmologist.