Why eye pressure raise?

Glaucoma: For the eye to function, a balance must exist between the aqueous fluid secreted by the ciliary body, and the outflow of fluid by way of the trabecular meshwork. If too much fluid is produced or too little drains out, the intraocular pressure increases, since after infancy, the eyeball cannot expand like a balloon. Untreated elevated eye pressure damages the optic nerve possibly causing blindness.