Experimental detection of retinal ganglion cell damage in vivo

In vivo detection of retinal ganglion cell (RGC) damage should have experimental and clinical relevance. A number of experimental models have been recently described to visualize RGCs in vivo. With retrograde injection of fluorescent tracers into the superior colliculus, lateral geniculate body, or optic nerve, RGCs can be detected in vivo with confocal laser scanning microscopy, fluorescent microscopy, or confocal scanning laser ophthalmoscopy. Although the resolution of these imaging techniques is limited to detecting only the cell bodies, the addition of adaptive optics has allowed in vivo visualization of axonal and dendritic processes. An ideal experimental model for detection of RGC damage should be non-invasive and reproducible. The introduction of a strain of transgenic mice that express fluorescent proteins under the control of Thy-1 promoter sequence has offered a non-invasive approach to detect RGCs. Long- term serial monitoring of RGCs over a year has been shown possible with this technique. In vivo imaging of RGCs could provide crucial information to investigating the mechanisms of neurodegenerative diseases and evaluating the treatment response of neuroprotective agents.