Optical strategies for in vivo retinal ganglion cell imaging

Retinal ganglion cells (RGCs) are essential in transmitting visual information from the retina to the brain, and their impairment has been linked to glaucoma and various neuro-ophthalmic diseases. In vivo imaging of RGC morphology and functionality is crucial for understanding the pathophysiology of retinal disease caused by RGC degeneration and their responses to treatments. This review provides a comprehensive overview of optical technologies suitable for in vivo RGC imaging. First, we compare scanning laser ophthalmoscopy, optical coherence tomography, and two-photon imaging and discuss their effectiveness in quantifying RGC damage in retinal disorders. Then, we discuss how functional vascular imaging techniques and specialized fluorophores, such as capQ and GCaMP, can be exploited to provide deeper insights into the physiology of RGCs. Lastly, we highlight the clinical translation of these imaging modalities, emphasizing handheld devices and clinical workflows to improve the image acquisition process. We also highlight the emerging role of machine learning, which automates tasks such as segmentation and disease classification to improve the efficiency of large data analysis.