Increased pressure in the front chamber of the eye due to blockage of its normal circulation of fluid. When the iris retracts and thickens (when the pupil of the eye is wide open), it blocks the drainage pathway for fluid in the eye. This causes the pressure in the eye to soar, which can damage the optic nerve and lead to blind- ness. The elevated pressure is ideally to be detected before the appearance of other symptoms of angle- closure glaucoma, so the pressure is routinely checked during eye exams. Symptoms of acute angle-closure glaucoma include severe eye and facial pain, nausea and vomiting, blurred vision, and a halo effect around lights. Acute angle-closure glaucoma is an emergency because optic nerve damage and vision loss can occur within hours of its onset. Angle-closure glaucoma tends to affect peo- ple born with a narrow angle between the cornea and iris.