Bahramizadeh-Sajadi Shima, Katoozian Hamid Reza, Ariza-Gracia Miguel Angel, Gholami Morteza, Baradaran-Rafii Alireza, Büchler Philippe
ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
PLoS One. 2024 Dec 5;19(12):e0311926. doi: 10.1371/journal.pone.0311926. eCollection 2024.
The cornea plays a role in the refractive power of the eye, and when its natural curvature and thickness are compromised by diseases such as keratoconus or high myopia, this results in loss of visual acuity. Intracorneal rings (ICRs) were developed as a treatment option to restore the natural corneal curvature by implanting rings into tunnels cut within the corneal stroma. However, selecting and placing the appropriate ring can be difficult, and predicting refractive outcomes is challenging.
The purpose of this study was to better understand the design parameters of the rings that determine postoperative refractive and mechanical outcomes.
We developed an automated finite element simulation pipeline for ICR implantation and tested 300 variations of 20 ICRs.
The outcome of ICR was dominated by the vertical size of the ring; 84% of the change in corneal curvature can be attributed to the vertical size of the ring, while only 13% were attributed to the detailed cross-sectional shape of the ring. However, the cross-sectional shape of the ring is limited to the change in axial length and contact pressure between the ring and the cornea. The horizontal dimension of the ring plays only a minor role in the postoperative outcome.
These results support Keraring's approach to ring scaling, in which only the vertical dimension of the ring is changed, while the horizontal dimension remains constant. Numerical models help to understand ICR outcomes, design implants, and personalize empirical nomograms to achieve more successful postoperative outcomes.
角膜在眼睛的屈光能力中起作用，当圆锥角膜或高度近视等疾病损害其天然曲率和厚度时，会导致视力丧失。角膜内环（ICR）作为一种治疗选择而被开发出来，通过将环植入角膜基质内切割的隧道中来恢复角膜的天然曲率。然而，选择和放置合适的环可能很困难，并且预测屈光结果具有挑战性。
本研究的目的是更好地理解决定术后屈光和力学结果的环的设计参数。
我们开发了一种用于ICR植入的自动化有限元模拟流程，并测试了20种ICR的300种变体。
ICR的结果主要由环的垂直尺寸决定；角膜曲率变化的84%可归因于环的垂直尺寸，而只有13%归因于环的详细横截面形状。然而，环的横截面形状限制了轴向长度的变化以及环与角膜之间的接触压力。环的水平尺寸在术后结果中仅起次要作用。
这些结果支持Keraring的环缩放方法，即仅改变环的垂直尺寸，而水平尺寸保持不变。数值模型有助于理解ICR结果、设计植入物并个性化经验性列线图以实现更成功的术后结果。
