PURPOSE: To investigate changes in Ocular Response Analyzer parameters after myopic LASIK. METHODS: Thirty myopic patients (60 eyes) undergoing bilateral LASIK were studied prospectively. Corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) measurements were obtained with the Ocular Response Analyzer before and after LASIK. Central corneal thickness and corneal fl ap thickness were also measured with optical coherence tomography. RESULTS: Compared with preoperative baseline values, corneal hysteresis, corneal resistance factor, IOPg, IOPcc, and central corneal thickness decreased postoperatively (P<.01). Corneal hysteresis (CH), corneal resistance factor (CRF), IOPg, IOPcc, and central corneal thickness (CCT) increased between 10 days and 3 months (post-hoc, P<.05). (The differences between the preoperative values and those at 3 months postoperatively are denoted by Δ.) The correlation of the ablation depth was stronger for ΔCRF (r=0.457) than for ΔCH (r=0.271). ΔCH was negatively correlated to flap thickness (r=-0.361) and the ratio of fl ap thickness to preoperative central corneal thickness (r=-0.442) whereas ΔCRF was not. ΔCH was positively correlated with ΔIOPcc, and ΔCRF was positively correlated with ΔIOPg. ΔIOPg was positively correlated with ΔCCT whereas ΔIOPcc was not. CONCLUSIONS: Corneal biomechanical properties measured by corneal hysteresis and corneal resistance factor were decreased at 10 days after LASIK. Minimal recovery (approximately 10% of the changes) was achieved by 3 months. The changes in biomechanical properties may affect IOP measurement.
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