Letter: Contrast sensitivity and viewing distance.
D000065:Accommodation, Ocular; D000328:Adult; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D007834:Lasers; D008297:Male; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology; D014792:Visual Acuity; D014794:Visual Fields