Nerve fiber counts of 16 normal human optic nerves from subjects aged 3.5 to 82 years showed a significant effect of age (P = .0207). The delay between death or enucleation and fixation also significantly affected the result (P = .0078). The mean (+/- S.E.M.) count for the 16 nerves was 1,244,005 +/- 20,033 fibers, giving a 99% confidence level between 1,192,400 and 1,295,610 fibers.