At study termination, retinas were individually isolated and snap frozen in liquid nitrogen. Retinal tissue was homogenized by adding 1 scoop of 0.9 to 2.0 mm diameter beads (no. SSB14B; Next Advance, Inc., Averill Park, NY, USA) and 150 μL of cell lysis buffer (Bio Rad, Hercules, CA, USA) to each retina. The tubes were placed in a Next Advance Bullet Blender Storm 24 and homogenized at a speed setting of 12 for 5 minutes at 4°C. The tubes were then removed and rocked for 15 minutes at 4°C and centrifuged at 13,000g for 5 minutes at 4°C. The supernatant was removed to a new tube, and a Bradford assay was conducted to determine protein concentration. Equal concentrations of total protein were separated by SDS-PAGE, transferred to PVDF, and detected using either a rabbit polyclonal antibody against phosphorylated Stat3 (catalog [cat.] no. 9145; Cell Signaling, Danvers, MA, USA) or a mouse monoclonal antibody against β-actin (cat. no. A3854; Sigma-Aldrich Corp., St. Louis, MO, USA).