MULTIMODAL OPTICAL COHERENCE ELASTOGRAPHY AND BRILLOUIN MICROSCOPY TO EVALUATE IN VIVO LENS BIOMECHANICS IN PRESBYOPIA

Abstract

Presbyopia is a loss of the dynamic accommodation response of our visual system to adjust to near and far stimuli and affects everyone as they age. Unlike static visual defects such as myopia, presbyopia affects the ability of the eye to adjust it’s focusing power since the lens must change both size and shape. Despite this, current therapies such as spectacles are static corrections of vision and do not treat the underlying cause of presbyopia. Growing evidence suggests that lens stiffening is critical to the inability of the eye to adjust focus, and that spatial varying mechanical properties of the lens are changing with age, and thus the structure-function relationship of these properties is of clinical importance. However, the major barrier to innovation in this space is the lack of clinical characterization and monitoring of accommodation biomechanics, which would aid both diagnostic monitoring and therapeutic planning. Optical coherence elastography (OCE) and Brillouin microscopy are promising technologies with synergistic strengths that can quantitatively assess lens elastography in vivo. To address this unmet need, we developed a clinical multimodal OCE/Brillouin system capable of measuring co-located Brillouin spectra and OCE information to map the depth-dependent elastic moduli. First, the multimodal OCE/Brillouin instrument was developed, and performance specifications were quantified. Next, the relationship between spatial-varying mechanical properties and overall mechanical properties were validated using porcine lenses and clinical OCE/Brillouin datasets to characterize the human lens. Finally, improvements to the Brillouin spectrometer acquisition time were made to reduce motion artifacts and improve translation into the clinical pipeline. This research will ultimately result in enabling patient-specific predictive models of accommodation changes from lens softening procedures for presbyopia treatment.