Cross section of eye, showing how pressure affects the retinaThere are many forms of Glaucoma, but the loss of sight is caused by damage to the retinal nerve fibre layer. This becomes the optic nerve, which takes the messages from the eyes to the brain.

Chronic Open Angle Glaucoma, the ‘sneak thief of sight’, usually has no symptoms. You lose vision from the outside as a result of slowly increasing pressure in the eye. Eye specialists usually treat this with drops.

Acute Closed angle glaucoma is a painful, sudden loss of vision in an eye. This usually gets better, but attacks become more frequent over time. This is usually cured with a laser.

Low Tension Glaucoma is similar in effect to Chronic Open Angle Glaucoma, but the pressure is normal.

Glaucoma is detected by your optometrist with a close look at the optic nerve, as well as measurement of your eye pressure. More sophisticated tests can involve testing of the visual field and nerve fibre measurements.