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Revolutionary Two-Photon Microscopy System for Retinal Imaging

Team of scientists from the Hong Kong University of Science and Technology developed an adaptive optics two-photon excitation fluorescence microscopy for retinal imaging.

Direct retinal imaging plays an important role not only in understanding diseased eye and ocular therapeutic discovery, but also study of a variety of well-defined central nervous system (CNS) disorders. The retina is the only part of the CNS that can be visualized using non-invasive optical imaging methods.

Current retinal imaging tools provide limited resolution, images taken are often inadequate in resolution. The resolve of subcellular structures and dynamics of retinal neurons, are mainly attributable to the large optical aberrations of the living eye.

In their work published in the journal, Light: Science and Applications in May 2020 the research team developed an adaptive optics two-photon excitation fluorescence microscopy (AO-TPEFM) using direct wave-front sensing for high-resolution in vivo fluorescence imaging of mouse retina. This allowed in vivo fundus imaging at an unprecedented resolution after full AO correction.

It will provide a necessary tool to study biological processes in the retina, and possibility of discovering more information about neurodegenerative disease.

“In this work, we advance two-photon microscopy for near-diffraction-limited and functional retinal imaging in living mice,” said Prof. Qu Jianan, lead researcher and Professor at the Department of Electronic and Computer Engineering, HKUST. “The localized two-photon fluorescence signals were used as nonlinear guide stars to achieve accurate measurement of ocular aberrations at the imaging location. We demonstrate that depth-resolved structures in different retinal layers can be resolved allowing for a wide range of studies which are infeasible otherwise.”

AO technology is used to improve the performance of an optical system through deforming a mirror. Thus, allowing it to correct for distortion(s). AO was first invented to remove the effects of atmospheric distortion in astronomical telescopes and laser communication systems.

“Direct wave-front sensing based on nonlinear fluorescent guide stars would be advantageous for accurate measurement of ocular aberrations at the exact imaging location, and thus permits highly efficient AO correction.” said Prof. Qu. “As the technology is more widely deployed, AO-TPEFM could help investigate the development of neurodegenerative diseases, since the eye offers a window into nerves of the central nervous system that link the eye with the brain.” [APBN]