Editor,—I read with interest the article by Koller and co-workers,1 in which the authors investigated causes and risk factors for membrane formation in the anterior chamber after argon laser trabeculoplasty (ALT). In their discussion the authors conclude that ALT and especially repeated ALT represent a risk for late membrane formation over the trabecular meshwork, which leads to late failure of ALT. They suggest that both late membrane formation and immediate intraocular pressure (IOP) spikes after ALT are induced by the same mechanism—that is, laser induced inflammation.

I agree with the authors that laser induced inflammation is a possible factor for subacute and late membrane formation over the trabecular meshwork. In a retrospective study2 in which the duration of success (IOP <22 mm Hg after treatment) was investigated …