Glaucoma is a term that describes a group of eye conditions that affect vision. Glaucoma often affects both eyes, usually in varying degrees with one eye sometimes developing glaucoma quicker than the other.

Glaucoma occurs when the drainage tubes (trabecular meshwork) within the eye become slightly blocked. This prevents eye fluid (aqueous humour) from draining properly.

If the fluid cannot drain properly, pressure builds up; this is called intraocular pressure. This pressure can damage the optic nerve (which connects the eye to the brain) and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).

If left untreated, glaucoma can cause blindness; but if it is diagnosed and treated early enough, further damage to vision can be prevented.