Increased phosphorylated neurofilament in the peripheral and central retina of patients with ALS. Phosphorylated neurofilament is shown in red using SMI 31, with nuclei counterstained with DAPI in blue. P-NF–positive spheroids ranging from 8 to 15 µm in diameter were observed in the peripheral retina (B, arrow) but not in the central retina in patients with ALS (D). Compared with controls (A, C), a stronger P-NF signal was observed in patients with ALS (B, D) in both peripheral (B) and central (D) retinal regions. (A) Control (case 9); (B) ALS (case 7); (C) control (case 3); (D) ALS (case 5). Abbreviations: RNFL = retinal nerve fiber layer; GCL = ganglion cell layer; IPL = inner plexiform layer; INL = inner nuclear layer; OPL = outer plexiform layer; ONL = outer nuclear layer. Scale bar = 50 µm.