The effect of excimer laser photorefractive keratectomy on intraocular pressure measurements using the Goldmann applanation tonometer.

Purpose: The authors determined whether photorefractive keratectomy (PRK) affects Goldmann applanation readings in human eyes.

Methods: The intraocular pressure (IOP) of 111 patients was measured using Goldmann applanation tonometry at baseline and 12 months after PRK. Ultrasonic corneal thickness measurements and keratometry were also obtained. Contralateral eyes were used as controls.

Results: There was a statistically significant decrease in mean tonometer readings in the treated eyes when compared with the control eyes (0.5 +/- 2.1 mmHg, P = 0.01) accompanied by a significant reduction in mean central pachymetry in the treated eyes (23 +/- 23 microns, P < 0.001). In the treated eyes, the mean spherical equivalent and mean central keratometry readings were significantly reduced by 3.3 +/- 1.5 and 2.2 +/- 1.2 diopters, respectively (P < 0.001).

Conclusion: Photorefractive keratectomy causes a mild lowering of the Goldmann tonometer readings. The reduction in IOP measurement is probably not enough to alter a therapeutic decision in an individual patient known to have glaucoma, but it may delay recognition and treatment of glaucoma.