Figure 1.

Toluidine blue stained retinal sections representing grading of degenerative changes in the optic nerve.

(A) Grade 1: normal optic nerve with intact axons. (B) Grade 2: early mild lesions with axonal swelling and appearance of glial cells (arrowhead). (C) Grade 3: *indicates nuclear clearing, # indicates vacuolation, arrow indicates axonal swellings and focal presence of degenerating axons. (D) Grade 4: nuclear clearing (*), vacuolation (#), axonal swellings and numerous degenerating axons spread all over the optic nerve section as indicated by arrow. (E) Grade 5: shows numerous nuclear clearing (*), vacuolation (#), axonal swelling and nearly all axons degenerating (arrows) across the entire section.