| Objective To evaluate and compare the consistency and changes of IOP measured by Goldmann applanation tonometer(GAT) and Non-contact tonometer(NCT) before and after FS-LASIK. Methods Cross-sectional study was used, IOP of GAT(IOP-GAT) and NCT(IOP-NCT) were measure in 303 eyes of 154 consecutive patients who underwent FS-LASIK in our hospital from Dec 2016 to Sept 2017. Besides, patients' age, absolute value of preoperative spherical equivalent(|SEpre|), preoperative radius of curvature(Rpre), preoperative central corneal thickness(CCTpre), preoperative IOP(IOP-GATpre, IOP-NCTpre), ablation depth(AD), ablation rate(AR) were studied to determine their influence on underestimation of IOP, and the stepwise regression formula should be obtained in the meantime. Results There was no statistical difference(P=0.192) between the average of IOP-GATpre and IOP-NCTpre(15.60±2.39 vs 15.49±2.58) mmHg. Meanwhile, Bland-Altman analysis showed the 95% limit of consistency value was 2.83 mmHg to 3.06 mmHg, postoperative IOP-GAT and IOP-NCT significantly decreased after FS-LASIK, but the reduction of IOP-NCT was much higher. There was a positive correlation of ΔIOP-GAT with|SEpre|, IOP-GATpre, CCTpre, AD, AR(P<0.05) and no correlation with age and Rpre. The regression formula was:ΔIOP-GAT=0.635×IOP-GATpre+15.633×AR-8.554(R2=0.504, F=204.163, P<0.05); meanwhile, there was a positive correlation between the reduction of ΔIOP-NCT with age,|SEpre|, IOP-NCTpre, CCTpre, AD,AR and no correlation with Rpre. The regression formula was:ΔIOP-NCT=0.603×IOP-NCTpre+20.493×AR-5.994(R2=0.653, F=274.921, P<0.05). Conclusion There exists a remarkable disagreement between IOP of GAT and NCT before and after FS-LASIK. Both IOP-GAT and IOP-NCT significantly decrease after FS-LASIK, but the reduction of IOP-NCT is much higher. Whatever, preoperative IOP measurement is the most important parameter that affects an underestimation of IOP after surgery. |
