The optical detection of retinal ganglion cell damage

We provide an overview of developments in the use OCT imaging for the detection of retinal ganglion cell damage in vivo that avoid use of any exogenous ligands to label cells. The method employs high resolution OCT using broad spectral light sources to deliver axial resolution of under 5 microns. The resolution approximates that of cellular organelles, which undergo degenerative changes that progress to apoptosis as a result of axon damage. These degenerative changes are manifest as the loss of retinal ganglion cell dendrites and fragmentation of the subcellular network of organelles, in particular, the mitochondria that support dendritic structure. These changes can alter the light scattering behaviour of degenerating neurons. Using OCT imaging techniques to identify these signals in cultured neurons, we have demonstrated changes in cultured cells and in retinal explants. Pilot studies in human glaucoma suggest that similar changes are detectable in the clinical setting. High resolution OCT can be used to detect optical scatter signals that derive from the retinal ganglion cell layer and are associated with neuronal damage. These findings suggest that OCT instruments can be used to derive quantitative measurements of retinal ganglion cell damage. Critically, these signals can be detected at an early stage of retinal ganglion cell degeneration when cells could be protected or remodeled to support visual recovery