Acute angle-closure glaucoma: Increased pressure in the front chamber (anterior chamber) of the eye due to sudden (acute) blockage of the normal circulation of fluid within the eye. The block takes place at the angle of the anterior chamber- the space at the junction of the cornea with the iris. This angle can be seen by looking at one's eye from the side with the slit lamp. Angle-closure glaucoma is more likely in people born with a narrow angle. People of Asian and Eskimo ancestry are at higher risk of developing it. Age and family history are risk factors. It occurs in older women more often than others.
When the pupil of the eye is wide open (dilated), the iris is retracted and thickened and it blocks the canal of Schlemm, a key component of the drainage pathway for fluid within the eye. Blocking the drainage canal of Schlemm sends the pressure within the eye shooting up. There is an abrupt increase in intraocular pressure (IOP) due to the buildup of aqueous (fluid) in the eye. The high pressure can damage the optic nerve (the nerve to the eye) and lead to blindness. The elevated pressure is best detected before the appearance of symptoms. That is why when the eyes are dilated in a doctor's office, eye pressures are checked. When symptoms of acute angle glaucoma do develop, they include severe eye and facial pain, nausea and vomiting, decreased vision, blurred vision and seeing haloes around light. The eye in a far advanced case of angle closure glaucoma appears red with a steamy (clouded) cornea and a fixed (nonreactive) dilated pupil. Acute angle-closure glaucoma is an emergency because optic nerve damage and vision loss can occur within hours of the onset of the problem.
Administering medications to lower the pressure within the eye is done first. In the past, a piece of the iris was then surgically removed in a procedure called an iridectomy to make a hole in the iris and create a channel (other than the canal of Schlemm) to permit the free flow of fluid. Today a comparable procedure can be done by laser to burn a small hole in the iris to keep the intraocular pressure within normal limits.