The distribution of the retinal sensitivity was measured using a fundus perimeter in 10 amblyopic patients with eccentric fixation. In 9 of 10 patients, the highest retinal sensitivity was detected in the eccentric fixation area. In no case was the peak sensitivity located in the fovea. These results suggests that the eccentric fixation develops in an attempt to fixate with a retinal locus having higher sensitivity, not visual acuity, than the fovea.