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

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.