Pseudoexfoliation glaucoma (PEX) is a form of glaucoma that is relatively common in older people. With PEX the system that drains the intraocular fluid is blocked by a white, flaky material originating from the lens of the eye. This increases eye pressure, which results in damage to the optic nerve. In the early stage a deterioration in side vision is experienced. Central vision is only lost in a later stage.