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Peripheral Iridotomy

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Updated May 10, 2011

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Definition: A peripheral iridotomy (PI) is a laser procedure for the treatment of narrow angle glaucoma and also a preventative treatment for people at risk for narrow angle glaucoma. Narrow angle glaucoma can come on suddenly, causing a variety of symptoms. If not treated within hours, people with narrow angle glaucoma can suffer substantial vision loss.

Narrow angle glaucoma, as the name implies, occurs when the drainage canal in the angle of the eye where the cornea meets the iris becomes narrower due to the iris moving forward. The drainage canal becomes blocked, and the pressure inside the eye rises quickly, as the intraocular fluid can no longer escape.

A peripheral iridotomy is performed to allow fluid to escape even if the angle becomes blocked. The procedure is performed by a physician with a Nd:Yag (neodymium-doped yttrium aluminium garnet) or an argon laser. A very tiny hole is created with the laser in the upper part of the iris. This hole acts to equalize the fluid between the front and back part of the eye.

A peripheral iridotomy creates little to no pain and is performed while the patient sits upright. The physician will use a device similar to a slit lamp biomicroscope used in an eye examination to focus the laser. Patients may have temporary side effects such as mild inflammation, blurred vision and a temporary increase in eye pressure. These side effects are managed successfully by topical medicated eye drops.

Also Known As: peripheral iridectomy
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