library_construction_protocol: Samples were dissociated in papain, followed by FACS sorting. For RNA-seq, RNA from 5,000 – 10,000 FACS-sorted RGCs were isolated with RNeasy Micro Kit (Qiagen), and RNA-seq libraries were prepared with SMART-Seq v4 Ultra Low Input RNA Kit (Clontech), following manufacturers' protocols. The cDNA was fragmented to 300 base pairs (bp) using the Covaris M220 (Covaris), and then the manufacturer's instructions were followed for end repair, adaptor ligation, and library amplification. The libraries were quantified by the Qubit dsDNA HS Assay Kit (Molecular Probes); Library size distribution and molar concentration of cDNA molecules in each library were determined by the Agilent High Sensitivity DNA Assay on an Agilent 2200 TapeStation system.