STTR Phase II: Refractive correction using non-invasive laser-induced refractive index change

这项小型企业创新研究的第二阶段项目使下一代视力矫正隐形眼镜的开发成为可能，该隐形眼镜基于一种名为LIRIC（激光诱导折射率变化）的新型光电化技术。全世界有超过23亿人患有视觉系统屈光不正，而超过5亿人无法获得充分的屈光矫正。眼镜是屈光矫正的一种选择，但戴眼镜可能存在实际限制，甚至与社会污名有关，特别是在青少年中。与此同时，隐形眼镜的视力矫正仅限于由其厚度轮廓决定光学处方的镜片。这对视觉质量、眼内稳定性和角膜健康都有负面影响。这项研究代表了视力矫正应用的根本转变，因为它改变了光学材料的折射率，使以前不可用的视力矫正器能够在薄而稳定的隐形眼镜上使用。LIRIC使用高重复率的飞秒激光对局部介质进行微修饰，以在水凝胶和活体角膜中产生定制的屈光矫正。LIRIC的工作原理是通过积累眼部材料的局部折射率（RI）变化，形成折射侧梯度折射率透镜。使用LIRIC而不是表面形状来改变折射率可以导致视力矫正的几个基本进展，对视力保健具有深远的影响：1)可以专门制造适合患者和稳定的隐形眼镜，并且屈光矫正与镜片形状分离；2)与现有方法相比，复杂和不规则的屈光校正（如不规则散光、老花眼和高阶像差）更容易书写，空间分辨率更高；3)多焦和衍射光学设计可用于老花眼和黄斑退行性矫正。通过第一阶段制造的LIRIC镜片观察的患者的视觉表现（视力和对比灵敏度）与对照镜片相当。第二阶段工作的目标是证明LIRIC以商业制造所需的工艺速度在隐形眼镜中工作。这项工作的目标是证明可以在15秒内成功处理6.5 mm的光学区域。为了有效地做到这一点，LIRIC工艺必须在超过10米/秒的激光扫描速度下实现1波以上的相变（波长为555nm）。

This Small Business Innovation Research Phase II project enables the development of the next generation of contact lenses for vision correction based on a novel photomodification technique called "LIRIC (Laser Induced Refractive Index Change)." More than 2.3 billion people world-wide suffer from refractive error in their visual system, while over 500 million have inadequate access to refractive correction. Glasses are an option for refractive correction, however there can be practical limitations and even social stigma associated with wearing glasses, particularly among adolescents. Meanwhile vision correction with contact lenses is limited to lenses whose optical prescription is determined by their thickness profile. This has negative consequences for visual quality, on-eye stability and corneal health. The research represents a fundamental shift in how vision correction is applied because it alters the refractive index of an optical material, enabling previously unavailable visual correctors in thin, stable contact lenses. LIRIC uses a high repetition rate, femtosecond laser to micro-modify the local medium to produce custom refractive corrections in hydrogels, and in living cornea. LIRIC works by accumulating localized refractive index (RI) changes in an ocular material to create a refractive lateral gradient index lens. Changing the refractive index using LIRIC instead of the surface shape can lead to several fundamental advances for vision correction, with profound implications for vision care: 1) contact lenses can be manufactured specifically for patient fit and stability with the refractive correction decoupled from the lens shape; 2) difficult and irregular refractive corrections (i.e. for irregular astigmatism, presbyopia, and higher order aberrations) could be written more easily and with better spatial resolution than with existing methods; 3) multifocal and diffractive optical designs can be utilized for presbyopic and macular degenerative corrections. Patients viewing through LIRIC lenses, created in Phase I, had visual performance (visual acuity and contrast sensitivity) on par with a control lens. The objective of the Phase II work is to demonstrate that LIRIC works in contact lenses at process speeds necessary for commercial manufacturing. The goal of this work is to demonstrate that a 6.5 mm optical zone can be successfully processed in 15 seconds. To effectively do so, the LIRIC process has to achieve more than 1 wave of phase change (at 555 nm wavelength) at laser scanning velocities in excess of 10 meter/second.