Laser treatment can be used as the initial treatment in some cases of glaucoma or it can be combined with medical or surgical treatment. There are different procedures for different types of glaucoma and the goals of the procedures vary according to the type of glaucoma being treated. The most commonly used types of glaucoma laser treatment are described below.

Laser trabeculoplasty

This procedure is performed on eyes that have open angles. The goal of the procedure is to lower the intraocular pressure. The laser beam is aimed at the trabecular meshwork, the structure through which fluid is drained. The laser beam stimulates the malfunctioning trabecular meshwork to improve its drainage of fluid. This procedure can lower intraocular pressure as much as some eye drops but it often needs to be repeated after a few years.

Laser iridotomy

This procedure is performed on eyes that have narrow or partially closed angles. A hole is created in the iris in the periphery, usually in an area that is covered by the upper lid. The hole enables fluid to flow directly from behind the iris to the anterior chamber without passing through the pupil. Since the fluid can easily pass through the hole to the anterior chamber, the fluid no longer has enough pressure to push the iris forward. So it helps the iris lie flat and keeps the iris from blocking the anterior chamber angle.

Laser iridoplasty

This procedure is done after or in combination with a laser iridotomy in certain cases of narrow or partially closed angles. The laser beam is aimed at the peripheral iris. The peripheral iris contracts in response to the laser beam and is pulled away from the anterior chamber angle. This procedure supplements the angle opening effect of a laser iridotomy.

Diode laser cyclophotocoagulation

In cases of severe, advanced glaucoma that do not respond well to medication and where glaucoma surgery or laser is not expected to succeed, the ciliary body (the fluid factory of the eye) can be partially destroyed using a laser beam or by freezing it. In glaucoma, the problem is one of too little drainage rather than overproduction of fluid, so most treatments aim to improve the drainage of fluid from the eye. Thus, partial destruction of the ciliary body is used mostly as a last resort. The general term for this procedure is cycloablation. A commonly used method for cycloablation uses a laser in a procedure called diode laser cyclophotocoagulation.

References:

1. Ritch R, Shields MB, Krupin T (Eds). The Glaucomas, 2^nd Edition. St. Louis, Missouri, USA, 1996, Mosby-Year Book, Inc.
2. Epstein DL, Allingham RR, Schuman JS (Eds). Chandler and Grant’s Glaucoma, 4^th Edition. Baltimore, Maryland, USA, 1997, Williams & Wilkins.
3. South East Asian Glaucoma Interest Group. Asia-Pacific Glaucoma Guidelines. Sydney, Australia, 2003-2004, SEAGIG.
4. European Glaucoma Society. Terminology and Guidelines for Glaucoma 2^nd Ed. Savona, Italy, 2003, EGS.