Previous studies of argon laser trabeculoplasty (ALT) have examined the effects of laser spot size, power, duration, anterior vs posterior spot placement, and extent of trabecular meshwork (TM) treated per session. Many surgeons perform ALT initially over 180° of TM and postpone further treatment if a sufficient response is obtained. Initially treating 180° of TM, reserving the other 180° until the initial treatment effect wears off, delays surgical intervention longer than initially treating 360° of TM.1
Most people have greater meshwork pigmentation inferiorly than superiorly. To our knowledge, no prior studies have addressed whether initially treating one specific region of TM is equally efficacious as treating any other specific region. We hypothesized that the intraocular pressure (IOP) response to initially treating the inferior half of the TM might be detectably different compared with initially treating the superior half.
One hundred two eyes of 80 consecutive patients with primary
Grayson D, Chi T, Liebmann J, Ritch R. Initial Argon Laser Trabeculoplasty to the Inferior vs Superior Half of Trabecular Meshwork. Arch Ophthalmol. 1994;112(4):446-447. doi:10.1001/archopht.1994.01090160020004