tokens: In all subjects with history of EMB - induced optic neuropathy , there was a mean loss of 72 % nerve fiber layer thickness in the temporal quadrant ( patient A , with eventual recovery of visual acuity and fields , 58 % loss ; patient B , with intermediate visual deficits , 68 % loss ; patient C , with chronic visual deficits , 90 % loss ), with an average mean optic nerve thickness of 26 +/- 16 microm .