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The development of technique for in-vivo imaging of retinal ganglion cells (RGCs) is important to understand the mechanisms of RGC degeneration and to test new treatment modalities.
With the addition of adaptive optics, it is possible to visualize the dendritic structures of macaque retinal ganglion cellsThis is of particular relevance in the evaluation of chronic progressive optic neuropathy like glaucoma, in which long term serial monitoring is required to study the course of the disease and the response to treatment. In the study by Gray et al. (121), macaques RGCs were retrograde labeled and imaged in vivo with a scanning laser ophthalmoscope (SLO). While a number of studies have demonstrated in-vivo imaging of RGCs with SLO, Gray et al. showed that it is possible to visualize the dendritic structures with the addition of adaptive optics. The key objective for imaging RGCs in vivo is to allow longitudinal evaluation. It is important to assess whether this technique is capable of detecting serial changes when the RGCs degenerate. As prolonged light exposure would be required to brighten the dendritic processes, this may limit its potential for serial assessment because of phototoxicity and bleaching of the fluorescence dye.
The techniques for in-vivo imaging of RGCs are rapidly evolving. A recent study by Walsh and Quigley1 also demonstrated in-vivo imaging of dendritic structures in a strain of transgenic mice expressing yellow fluorescent protein in a subset of RGCs using a confocal scanning laser microscope. Further investigations are required to examine the use of these imaging techniques for studying cellular changes of RGC degeneration.