Frigelli Matteo, Ariza Gracia Miguel A, Aydemir M Enes, Torres-Netto Emilio A, Hafezi Farhad, Rozema Jos, Büchler Philippe, Kling Sabine
ARTORG Center for Biomedical Engineering Research, University of Bern, Switzerland.
ELZA Institute AG, Zürich, Switzerland.
Invest Ophthalmol Vis Sci. 2025 Sep 2;66(12):51. doi: 10.1167/iovs.66.12.51.
To validate an existing finite element model (FEM) for predicting the flattening effect of corneal cross-linking (CXL) in a clinical scenario and to use this model to investigate the parameters that most influence CXL-induced flattening effects.
Retrospective data were collected from two clinical cohorts, each with 20 patients receiving either standard or customized CXL. Data were collected before surgery and at the six-month follow-up. Both CXL treatments were simulated with a FEM calibrated on experimental data. Standard anterior corneal geometry indexes (e.g., sphere, cylinder), as well as the curvature changes observed at follow-up were compared to those predicted by FEM simulations.
At follow-up, patients who underwent customized CXL exhibited more corneal flattening compared to those who received standard CXL (Kmax-t: -2.28 ± 1.4 D vs. -0.81 ± 1.5 D; P < 0.001). The FEM-predicted curvature reduction in the central CXL regions showed a significant correlation with the follow-up data for both standard (R2 = 0.48, P < 0.01) and customized CXL (R2 = 0.59, P < 0.01). Compared to follow-up data, standard CXL model showed concordance correlation coefficients > 0.9 for nine corneal geometry parameters and customized CXL model for three. Sensitivity analysis demonstrated that a 3 mm Hg increase in intraocular pressure (IOP) combined with a 10% weaker keratoconus region alters flattening outcomes by up to 20%.
Customized CXL induces a flattening of about 2 diopters in the cone region six months after surgery. The model adequately captured the curvature corrections induced by the treatment in the keratoconus cone region, but showed reduced accuracy in predicting global corneal metrics, particularly for customized CXL. The induced flattening effects depend on the IOP, keratoconus-induced biomechanical weakening, and the fluence delivered to the cone.
验证一个现有的有限元模型（FEM），用于预测临床场景中角膜交联（CXL）的扁平效应，并使用该模型研究对CXL诱导的扁平效应影响最大的参数。
从两个临床队列中收集回顾性数据，每个队列有20例接受标准或定制CXL的患者。在手术前和六个月随访时收集数据。两种CXL治疗均使用根据实验数据校准的FEM进行模拟。将标准的角膜前表面几何指数（如球镜、柱镜）以及随访时观察到的曲率变化与FEM模拟预测的结果进行比较。
随访时，接受定制CXL的患者比接受标准CXL的患者表现出更多的角膜扁平（最大曲率-角膜顶：-2.28±1.4D对-0.81±1.5D；P<0.001）。FEM预测的中央CXL区域的曲率降低与标准CXL（R2=0.48，P<0.01）和定制CXL（R2=0..59，P<0.01）的随访数据均显示出显著相关性。与随访数据相比，标准CXL模型对九个角膜几何参数的一致性相关系数>0.9，定制CXL模型对三个角膜几何参数的一致性相关系数>0.9。敏感性分析表明，眼内压（IOP）升高3mmHg并伴有圆锥角膜区域强度减弱10%会使扁平结果改变高达20%。
定制CXL在术后六个月可使圆锥区域扁平约2屈光度。该模型充分捕捉了圆锥角膜圆锥区域治疗引起的曲率矫正，但在预测整体角膜指标方面准确性降低，尤其是对于定制CXL。诱导的扁平效应取决于IOP、圆锥角膜引起的生物力学减弱以及传递到圆锥的能量密度。
