The decrease of corneal stiffness is the key factor leading to keratoconus, and the corneal collagen fiber stiffness and fiber dispersion are closely related to the corneal biomechanical properties. In this paper, a finite element model of human cornea based on corneal microstructure, namely collagen fiber, was established before and after laser assisted in situ keratomileusis (LASIK). By simulating the Corvis ST process and comparing with the actual clinical results, the hyperelastic constitutive parameters and corneal collagen fiber stiffness modulus of the corneal material were determined before and after refractive surgery. After LASIK, the corneal collagen fiber stiffness modulus increased significantly, and was highly correlated with central corneal thickness (CCT). The predictive relationship between the corneal collagen fiber stiffness modulus and the corresponding CCT before and after surgery was: = exp(9.14 - 0.009CCT ), = exp(8.82 - 0.008CCT ). According to the results of this study, the central corneal thickness of the patient can be used to estimate the preoperative and postoperative collagen fiber stiffness modulus, and then a personalized corneal model that is more consistent with the actual situation of the patient can be established, providing a theoretical reference for more accurately predicting the safe surgical cutting amount of the cornea.
Biomechanical Phenomena ; Cornea ; Corneal Topography ; Finite Element Analysis ; Humans ; Keratomileusis, Laser In Situ ; Myopia

Objective:To compare the effects of intensive and standard blood pressure control on the outcomes of patients with acute ischemic stroke in the anterior circulation who have successfully recanalized after endovascular therapy (EVT).Methods:A multicenter, open-label, blinded-endpoint, randomized controlled design was used. Patients with anterior circulation stroke received EVT and successfully recanalized in Nanjing First Hospital, Nanjing Medical University and several branch hospitals from July 2020 to October 2022 were prospectively included. They were randomly divided into the intensive blood pressure control group (target systolic blood pressure [SBP] 100-120 mmHg) or the standard blood pressure control group (target SBP 121-140 mmHg). The blood pressure of both groups needs to achieve the target within 1 h and maintain for 72 h. The primary outcome endpoint was outcome at 90 d, and the good outcome was defined as a score of 0-2 on the modified Rankin Scale. Secondary outcome endpoints included early neurological improvement, symptomatic intracranial hemorrhage (sICH) within 24 h, and death and serious adverse events within 90 d.Results:A total of 120 patients were included, including 63 in the intensive blood pressure control group and 57 in the standard blood pressure control group. There was no statistically significant difference in baseline characteristics between the two groups. The SBP at 72 h after procedure was 122.7±8.1 mmHg in the intensive blood pressure control group and 130.2±7.4 mmHg in the standard blood pressure control group, respectively. There were no significantly differences in the good outcome rate (54.0% vs. 54.4%; χ2=0.002, P=0.963), the early neurological improvement rate (45.2% vs. 34.5%; χ2=1.367, P=0.242), the incidence of sICH (6.3% vs. 3.5%; P=0.682), mortality (7.9% vs. 14.0%; χ2=1.152, P=0.283) and the incidence of serious adverse events (12.7% vs. 15.8%; χ2=0.235, P=0.628) at 90 d between the intensive blood pressure control group and the standard blood pressure control group. Conclusion:In patients with anterior circulation stroke and successful revascularization of EVT, early intensive blood pressure control don’t improve clinical outcomes and reduce the incidence of sICH.