Simultaneous in vivo confocal reflectance and two-photon retinal ganglion cell imaging based on a hollow core fiber platform

We have developed a compact hollow core fiber (HCF)-based imaging platform capable of simultaneous in vivo confocal reflectance and two-photon imaging through the mouse pupil. We demonstrate the performance of this platform by imaging retinal ganglion cells (RGCs) in which the fluorophores YFP and GCaMP3 are expressed in Thy1-YFP-16 and Thy1-GCaMP3 transgenic mice, respectively. Confocal reflectance images of the mouse retina served as a reference for the simultaneous acquisition of the two-photon signals that clearly showed RGCs with single-cell resolution. The use of an HCF platform makes the system compact with future application in the longitudinal investigation into the structure and function of healthy and diseased RGCs.