Dino Tsuchiyama, Aeromedical Consultation Service Ophthalmology Branch electro-diagnostic technician, confirms settings on a multifocal electroretinogram machine before conducting a test on Lt. Col. Christopher Cannon (image on screen). The test helps determine the health of the retina, if there is damage to the optic nerve and the overall health of the eye. (U.S. Air Force photo/John Harrington)