Glaucoma Surgery Download PDF, 1.12MB, PDF Just as a car tyre has a certain pressure, your eye maintains its shape by its intraocular pressure (IOP). This pressure is generated by the balance of fluid (aqueous humour) entering and leaving the eye. If fluid leaving the eye is reduced or blocked, pressure in the eye rises, leading to the disease called glaucoma. In glaucoma, there is permanent and progressive damage to the eyeball nerve (optic nerve), which can lead to irreversible blindness. [Please download the PDF file if you are unable to view the image below.]