Pneumotonometry versus Goldmann tonometry after laser in situ keratomileusis for myopia

Abstract

Purpose To assess the reliability of intraocular pressure (IOP) measurement by Goldmann applanation tonometry (GAT) versus pneumotonometry in patients after laser in situ keratomileusis (LASIK) for myopia. Setting Shiley Eye Center, University of California San Diego, La Jolla, California, USA. Methods In this prospective study, 31 eyes of 17 patients were evaluated before and 1 month after having LASIK for myopia. A masked observer measured preoperative and postoperative IOP by GAT centrally and by pneumotonometry at the center and the periphery of the cornea. Central corneal thickness and curvature were evaluated. Results Preoperative IOP showed a good correlation between GAT and pneumotonometry values ( r = 0.82). Mean postoperative IOP by GAT was lower by 3.8 mm Hg ± 2.2 (SD) (26.3% ± 15.2%) than by pneumotonometry: 2.3 ± 2.8 mm Hg (15.4% ± 10.7%) ( P = .01). There were no statistically significant differences in central IOP versus peripheral IOP measured by pneumotonometry ( P = .4). Regression analysis showed no statistically significant differences in IOP as a function of change in corneal thickness or change in corneal curvature with either device. Conclusion Postoperatively, there was a decrease in IOP measured by central GAT that was statistically significant. Differences in pneumotonometry were less substantial, with greater reliability of pneumotonometry than GAT after LASIK.