OPTN and glaucoma: We have previously established that hPSC-derived RGCs with the glaucoma-associated OPTN(E50K) mutation exhibit morphological and functional deficits [27, 58] and more recently, we demonstrated that astrocytes with the OPTN(E50K) mutation can confer neurodegenerative phenotypes upon otherwise healthy RGCs [30], underscoring the important role that astrocytes play in overall homeostasis.