title: Effect of levodopa on the human dark adaptation threshold.
abstract: BACKGROUND
  In several species there is strong evidence that the retinal dopamine turnover is influenced by retinal dark and light adaptation. In the human retina, dopamine has been found in amacrine and interplexiform cells.
  
  
  METHODS
  In the present study, the influence of orally administered levodopa on the human dark adaptation was investigated in healthy subjects using the Goldmann-Weekers adaptometer. To exclude effects of levodopa on the pupil size, a second group was examined after pupil dilation before each examination. A third and fourth group were examined under the same conditions as the first two groups, but without levodopa administration.
  
  
  RESULTS
  Levodopa caused a uniform threshold elevation throughout dark adaptation with undilated and dilated pupils. No effect on sensitivity was observed in the control groups.
  
  
  CONCLUSIONS
  These results show a dopaminergic reduction in sensitivity during human dark adaptation.
authors.affiliation: Kantonsspital St. Gallen, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Gottlob
authors.forename: K
authors.initials: K
authors.lastname: Strenn
authors.forename: B
authors.initials: B
authors.lastname: Schneider
mesh_terms: D000284:Administration, Oral; D000328:Adult; D003623:Dark Adaptation / Q000187:drug effects*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D011680:Pupil / Q000502:physiology; D012684:Sensory Thresholds / Q000187:drug effects; D014796:Visual Perception / Q000187:drug effects*
chemical_list: D007980:Levodopa