The clear fluids in the eye are called the aqueous humour and the vitreous humour . The pressures they exert keeps the eyeball in a fixed size and shape.
Aqueous humour is produced by the eye continuously.
When it does not drain properly then there is greater pressure inside the eye which is symptomatic of glaucoma . This increased pressure affects the retina at the back of the eye. The blood supply to the nerves of the retina is reduced and the nerves start to die. As the optic nerve degrades, blind spots develop and vision changes. Without treatment, glaucoma can cause blindness.