Disease marked by increased pressure in the eye .
A result of blockage of the flow of fluid (aqueous humour) at the outer edge of the iris, this pressure is transmitted to the optic nerve head and the retina . Chronic glaucoma can be treated with drugs that contract the pupil. Acute glaucoma may be intermittent. Permanent relief requires surgery to provide an outlet for the fluid. Either type causes vision impairment or blindness if untreated.