What is it? When, why and how is it done in glaucoma?
There are many different kinds of laser used in ophthalmology and specifically in glaucoma. A laser is amplified light energy which can be targeted to different parts of the eye with minimal or no damage to surrounding structures. Argon laser is a blue-green spectrum laser which targets pigmented or darker structures in the eye such as the iris.
Argon laser is used for:
Peripheral Iridoplasty (ALPI):
- WHEN: It is used for selected people with a plateau iris (Zada, Dunn, and White 2018) and occasionally for acute angle closure (Ng, Ang, and Azuara-Blanco 2008)
- WHY: When the edge of the iris is too close to the cornea (clear front window) it risks blocking the drainage of aqueous fluid from the angle of the eye. This can cause the pressure inside the eye (IOP) to increase and worsen glacuoma damage to the optic nerve
- HOW: After local anaesthetic a lens is placed on the surface of the eye to give a clearer view to the doctor and avoid the worry of blinking. The laser is then applied around the edge of the iris to shrink down the thick tissue blocking the drainage angle. There is very minimal discomfort with this procedure, and it takes around 5 minutes per eye to perform.
Argon Laser Trabeculoplasty (ALT):
- WHEN: This has now been almost entirely replaced by selective laser trabeculoplasty (SLT) which is equally effective but leaves no damage to the eye tissues (Kent et al. 2015; Juzych et al. 2004).
- WHY: When the IOP is too high and damage to the optic nerve is worsening, your ophthalmologist can improve the drainage of fluid and lower the IOP from the eye using this procedure.
- HOW: after local anaesthetic a lens is placed on the surface of the eye to give a clearer view to the doctor, focus the laser and avoid the worry of blinking. The laser is then applied around the drainage angle. There is very minimal discomfort with this procedure, and it takes around 5 minutes per eye to perform.
References:
Juzych, Mark S., Vikás Chopra, Michael R. Banitt, Bret A. Hughes, Chaesik Kim, Mark T. Goulas, and Dong H. Shin. 2004. “Comparison of Long-Term Outcomes of Selective Laser Trabeculoplasty versus Argon Laser Trabeculoplasty in Open-Angle Glaucoma.” Ophthalmology 111 (10): 1853–59.
Kent, Shefalee S., Cindy M. L. Hutnik, Catherine M. Birt, Karim F. Damji, Paul Harasymowycz, Francie Si, William Hodge, Irene Pan, and Andrew Crichton. 2015. “A Randomized Clinical Trial of Selective Laser Trabeculoplasty versus Argon Laser Trabeculoplasty in Patients with Pseudoexfoliation.” Journal of Glaucoma 24 (5): 344–47.
Ng, W. S., G. S. Ang, and A. Azuara-Blanco. 2008. “Laser Peripheral Iridoplasty for Angle-Closure.” Cochrane Database of Systematic Reviews 2008/07/23 (3): Cd006746.
Zada, Mark, Hamish Dunn, and Andrew White. 2018. “Pilocarpine Test May Predict Success of Argon Laser Peripheral Iridoplasty.” Clinical & Experimental Ophthalmology 46 (9): 1089–91.