The influence of peripheral iridotomy on the intraocular pressure course in patients with pigmentary glaucoma

Purpose: To evaluate the influence of laser peripheral iridotomy on the long-term intraocular pressure course for patients with pigmentary glaucoma. Patients and Methods: Retrospective analysis of data contributed by members of the American Glaucoma Society on patients with bilateral pigmentary glaucoma, who received uniocular laser iridotomy. The main outcome measure was the post-laser intraocular pressure course of the treated eyes, compared with the fellow, untreated eyes. Results: Sixty patients were included in the study, 46 of whom were observed for a minimum of 2 years (mean 70.3 +/- 26.0 months; range 24-113 months). Among the 14 patients who were observed for less than 2 years, the mean intraocular pressure in the treated eyes increased 0.36 +/- 2.63 mm Hg, compared with the fellow, untreated eyes. Among the 46 patients, observed for 2 years or more, the mean intraocular pressure in the treated eyes decreased 4.0 +/- 5.4 min Hg, compared with 1.9 +/- 3.8 mm Hg in the fellow eyes (P = 0.005). However, analysis by linear models indicates that a higher mean baseline intraocular pressure in the treated eyes accounts for the apparent treatment effect of laser peripheral iridotomy. Conclusion: The study does not provide support for the benefit of laser peripheral iridotomy in the long-term intraocular pressure control of patients with pigmentary glaucoma, when the data are subjected to rigid statistical analysis. This does not disprove the benefit of laser iridotomy in this patient population, but underscores the need for a large, prospective study to address the question.