Study On Biomechanical Changes Of Corneal FS-LASIK, SBK And LASEK

Objective:Use Corvis ST to study corneal biomechanics influenced by residual stromal thickness and intraocular pressure after FS-LASIK.Methods:Select two healthy corneosclera of cadaver eyes preserved in EUSOL-C,fixed in artificial anterior chamber,operate FS-LASIK surgery and reserve setting corneal stroma bed thickness,use Corvis ST to measure the biomechanical parameters under different intraocular pressure.Results:Intraocular pressure and AT1?AT2?DA have obvious correlation under different corneal stroma bed thickness.When substrate bed less than 200 microns,corneal biomechanical parameters and the correlation of intraocular pressure significantly enhanced;the corneal stroma bed thickness and Vin?HC-radius have obvious correlation within normal intraocular pressure,and when intraocular pressure is higher than normal,corneal stroma bed thickness are related to AT1?AT2?HC-radius?DA,we also find a a turning point at 200 microns in correlation curve of HC-radius.Conclusion:intraocular pressure of patients and the operation parameters Play important roles in the safety of surgery.According to the results of this study,we believe that the patients with intraocular pressure under 20 mmHg and preserve more than 300 microns residual stromal thickness are good for maintaining postoperative corneal biomechanical stability.Objective:To study the influence of three different corneal refractive surgeries on corneal biomechanics.Methods:50 patients(97 eyes)were enrolled in this prospective case series study.There were 55 eyes underwent FS-LASIK,21 eyes underwent SBK and 21 eyes underwent LASEK.AT1?AT2?AL1?AL2?Vin?Vout?PD?HC-radius?DA?IOP?CCT were obtained with Corvis ST preoperatively and immediately?1 day?1 week?1 month?3 months postoperatively.Results:There was varying significance of correlation between AT1?DA?IOP with CCT?RST?AD in FS-LASIK,AT1 IOP with CCT?age?AD and DA with age in SBK,AT1 with CCT and DA with age and IOP with CCT in LASEK.There are statistically significances in AT1?DA?IOP between the postoperative follow-up time and pre-operation.AT1?DA?IOP have statistical differences between three different surgeries in after surgery and postoperative 1 week,and no statistical difference after 3 months postoperative.Conclusion:Corneal biomechanics are influenced by CCT and age etc,there are different influences on corneal biomechanical properties between different refractive surgeries.As corneal epithelium and stromal were gradually healing,biomechanics became stable.In this study,the stability from strong to week are LASEK?FS-LASIK?SBK.