Acute glaucoma. Close-up of an eye diseased with acute (closed-angle) glaucoma. The eye is inflamed with the white sclera become red due to pressure on blood vessels, the black pupil is enlarged and the surrounding iris is a milky colour. There is pus secretion from the tear duct. Glaucoma is a sight-threatening condition characterised by an increase in aqueous humour pressure within the eye (here: 72mm pressure, shallow anterior chamber). Primary glaucoma arises in the absence of another eye disease; secondary glaucoma results from a pre-existing eye disorder. Primary glaucoma occurs increasingly with age, and treatment is to reduce intraocular pressure with drugs or by surgery.