Engineering Applications of Laser Department, National Institute of Laser Enhanced Sciences, Cairo University, Giza, Egypt.
Medical Applications of Laser Department, National Institute of Laser Enhanced Sciences, Cairo University, Giza, Egypt.
Int J Numer Method Biomed Eng. 2024 Oct;40(10):e3861. doi: 10.1002/cnm.3861. Epub 2024 Aug 18.
Laser corneal reshaping is a safe and effective technique utilized to treat common vision disorders. An advanced laser delivery system equipped with a pulsed UV laser with specific parameters is used to ablate parts of the cornea surface to correct the existing refractive error. The argon fluoride (ArF) excimer pulsed gas laser at 193 nm is the most employed type in the commercial devices for such treatments. This laser is generated using a mixture of Argon, Fluorine, and a significant amount of Neon gases. However, due to the ongoing Russian-Ukraine war, the availability of Neon gas is currently very limited, as this region is considered the primary supplier of pure Neon gas. Consequently we suggest replacing the common ArF laser source in the commercial devices with a solid-state (forth harmonic neodymium-doped yttrium aluminum garnet laser at 266 nm). This replacement uses the same operation parameters, optics, and scanning algorithm. Parameters from five commercial devices (Zeiss MEL 90, Technolas TENEO 317, Alcon Wave Light EX 500, Schwind Amaris 750 s, OptoSystems MICROSCAN VISUM) were compared with those of the i-ablation device, a research device that uses a 266 nm laser source. Our goal is to reduce production costs through a simple modification that has a significant impact. Consequently, the present study aims to find an alternative laser source for the current ArF laser without exchanging the complete system's design. This recommendation is based on a numerical simulation study. The thermal effect on a human cornea model was numerically evaluated using finite-element solutions of Pennes' bioheat equation on the COMSOL platform by applying two laser wavelengths. The results demonstrated that changing the laser source significantly impacts the thermal effect, even with the same laser settings. All studied devices showed a reduction in the thermal effect to below 40°C, compared with nearly 100°C under ordinary conditions.
激光角膜重塑是一种安全有效的技术，用于治疗常见的视力障碍。先进的激光传输系统配备了具有特定参数的脉冲紫外激光，用于消融角膜表面的部分以矫正现有的屈光不正。193nm 的氩氟（ArF）准分子脉冲气体激光是此类治疗中商业设备中最常使用的类型。这种激光是通过氩气、氟气和大量氖气的混合物产生的。然而，由于俄罗斯和乌克兰之间的持续战争，氖气的供应目前非常有限，因为该地区被认为是纯氖气的主要供应地。因此，我们建议用固态（266nm 掺钕钇铝石榴石激光的四倍频）取代商业设备中常见的 ArF 激光源。这种替代使用相同的操作参数、光学器件和扫描算法。对五个商业设备（蔡司 MEL 90、Technolas TENEO 317、Alcon Wave Light EX 500、Schwind Amaris 750s、OptoSystems MICROSCAN VISUM）的参数与 i-ablation 设备（使用 266nm 激光源的研究设备）的参数进行了比较。我们的目标是通过简单的修改来降低生产成本，这种修改具有重大影响。因此，本研究旨在在不更换整个系统设计的情况下，为当前的 ArF 激光找到替代激光源。这一建议是基于数值模拟研究得出的。通过在 COMSOL 平台上对彭内斯生物传热方程的有限元解进行数值评估，研究了两种激光波长对人眼角膜模型的热效应。结果表明，即使激光设置相同，改变激光源也会显著影响热效应。与普通条件下近 100°C 的温度相比，所有研究的设备都显示出热效应降低到 40°C 以下。
