Intraocular pressure assessment in both eyes of the same patient after laser in situ keratomileusis

PURPOSE: To measure intraocular pressure (IOP) after laser in situ keratomileusis (LASIK) in both eyes of the same patient and analyze the correlation between IOP measurement and keratometric (K) power, central corneal thickness (CCT), and laser ablation depth. SETTING: Private practice, Kaohsiung, Taiwan. METHODS: This prospective cohort study enrolled patients with myopia or myopic astigmatism. In all patients, the targeted post-LASIK spherical equivalent was within +/- 0.25 diopter. The IOP was measured using noncontact tonometry; K power, by autokeratorefractometry; and CCT, by ultrasound pachymetry. Laser ablation depth was determined using the excimer laser's software, and the ratio of laser ablation depth to decreased IOP was calculated. Correlations were determined by stepwise multiple regression analysis and the Mann-Whitney U test. RESULTS: High preoperative IOP was significantly associated with high postoperative IOP (P<.001) and with a large decrease in IOP (P<.001). Thus, 62.7% and 37.5% of postoperative IOP and decreased IOP measurements, respectively, were explainable by the preoperative IOP. Postoperative IOP (P = .904), decreased IOP after LASIK (P = .479), and the ratio of laser ablation depth to decreased IOP (P = .971) did not significantly differ and were positively correlated (P<.001) between eyes of the same patient. CONCLUSIONS: The IOP measurement reduction after LASIK was greater in cases of higher preoperative IOP and smaller in cases of lower preoperative IOP. The IOP measurements after LASIK were not significantly associated with laser ablation depth, and the measurements were similar and proportional in eyes of the same patient.