Abstract: Objective To establish and validate the regression formula of intraocular pressure(IOP)by analyzing the influencing factors of IOP following laser assisted in situ keratomileusis(LASIK). Methods A prospective case study was performed on 235 myopia patients receiving LASIK. After self-contrast of randomized paired design, the influencing factors of IOP noncontact tonometer(IOP_NCT)were analyzed. The multiple regression formula to forecast the changes of IOP_NCT after LASIK was established and verified. Results The preoperative IOP_NCT was not related to gender, dominant eye, age or keratometry of the patients(P>0.05), but positively related to the central corneal thickness(CCT)and absolute value of spherical equivalent. The IOP_NCT changes after LASIK(△IOP_NCT)were not related to age, keratometry or stroma bed thickness of the patient(P>0.05), but positively related to the preoperative IOP_NCT, CCT, ablation depth, ablation rate(AR)and absolute value of spherical equivalent. The multiple linear regression formula of the IOP_NCT changes after LASIK was: △IOP_NCT = IOP_NCT-preop×0.552 + AR×0.158-6.219(R2=0.561, P<0.01). After Verification by practical cases, there was no statistically significant difference between the estimated values and measured values of the IOP_NCT changes after LASIK(t=-0.129, P=0.897). Conclusion The IOP_NCT of pre-LASIK is not related to gender, dominant eye, age or keratometry of the patient, but positively related to the central corneal thickness and absolute value of spherical equivalent. The △IOP_NCT is not related to age, keratometry or stroma bed thickness of the patient, but positively related to the IOP_NCT of pre-LASIK, central corneal thickness, absolute value of spherical equivalent, ablation depth and rate. The values of △IOP_NCT can be estimated by the regression formula.

Key words: Myopia, Intraocular pressure, Laser assisted in situ keratomileusis, Regression analysis