Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, United States.
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, United States.
J Biomech. 2022 May;136:111054. doi: 10.1016/j.jbiomech.2022.111054. Epub 2022 Mar 18.
Accommodation alters the shape of the eye lens to change focus from distant to near vision. This function declines with age in the development of presbyopia and most people experience a near total loss of accommodative ability by 55 years. Currently, there are no surgical procedures that correct presbyopia, but considerable work has been done in the development of accommodative intraocular lenses (AIOLs) implanted during cataract surgery. Despite these efforts, AIOLs only restore ∼ 20% of youthful accommodative amplitude and they suffer from high rates of visually-debilitating fibrosis. An important design tool that is lacking that could aid in improving AIOL designs is modeling. Herein, we addressed this need through the development of a fully 3-D finite element model that was used to predict the behavior of a dual-optic AIOL implanted within the post-surgical lens capsule. Models of the native human lens were developed to identify the stress-free configuration of the lens capsule needed to accurately predict the accommodated state of the lens and the configuration of the zonular traction needed for the disaccommodated state. The AIOL model demonstrated the functional importance of implant stiffness and predicted an approximately linear relationship between zonular traction magnitude and axial displacement of the optics. To our knowledge, this is the first model that can be used to gain insights into AIOL efficacy. It provides a foundation for continued development of a predictive tool that could ultimately improve AIOL designs that seek to restore youthful accommodative function.
适应改变眼睛晶状体的形状，以改变从远视到近视的焦点。随着年龄的增长，这种功能在远视的发展中下降，大多数人在 55 岁时几乎完全丧失了适应能力。目前，还没有手术程序可以矫正远视，但在白内障手术中植入可调节人工晶状体 (AIOL) 的开发方面已经做了大量工作。尽管有这些努力，AIOL 仅恢复了约 20%的年轻适应幅度，并且它们容易出现高比例的视觉致残纤维化。缺乏可以帮助改进 AIOL 设计的重要设计工具是建模。在这里，我们通过开发一个完全 3-D 有限元模型来解决这一需求，该模型用于预测在术后晶状体囊内植入的双光 AIOL 的行为。开发了天然人晶状体的模型，以确定晶状体囊的无应力配置，这对于准确预测晶状体的适应状态以及用于非适应状态的悬韧带牵引配置是必要的。AIOL 模型证明了植入物刚度的功能重要性，并预测了在光学器件的轴向位移和子午线牵引强度之间存在近似线性关系。据我们所知，这是第一个可用于深入了解 AIOL 功效的模型。它为继续开发预测工具奠定了基础，该工具最终可能会改进寻求恢复年轻适应功能的 AIOL 设计。
