title: Chromatic pupillometry in patients with retinitis pigmentosa.
abstract: OBJECTIVE
  To evaluate the chromatic pupillary response as a means of assessing outer and inner retinal function in patients with retinitis pigmentosa (RP).
  
  
  METHODS
  Evaluation of diagnostic technology.
  
  
  METHODS
  Thirty-two patients with RP and visual loss and 43 normal subjects.
  
  
  METHODS
  Patients were tested with a chromatic pupillometer using red and blue lights (1, 10, and 100 cd/m(2)), and their pupil responses were compared with those from 43 normal subjects (reported previously). Visual field and electroretinography (ERG) results were examined and compared with the pupil responses.
  
  
  METHODS
  The percent pupil contraction of the transient response to a low-intensity (1 cd/m(2)) blue light and high-intensity (100 cd/m(2)) red light and the sustained response to a high-intensity blue light was calculated for 1 eye of each subject.
  
  
  RESULTS
  The pupil responses to red and blue light at all intensities were recordable in all patients except 1, whose pupil responded only to bright blue light. There was a significant difference of the pupil response between patients with RP and normal subjects in testing conditions that emphasized rod (1 cd/m(2) blue light) or cone (100 cd/m(2) red light) contribution (P<0.001). Patients with a non-recordable scotopic ERG showed significantly reduced pupil responses (P<0.001) to low-intensity blue light (1 cd/m(2)). Patients with a non-recordable or abnormal photopic ERG showed significantly reduced pupil responses (P<0.05) to high-intensity red light (100 cd/m(2)). Patients with a nonrecordable ERG had the most visual field loss and reduced pupil responses. Unexpectedly, patients with RP showed a slower re-dilation of the pupil after termination of bright blue light compared with red light, a pattern not observed in normal subjects.
  
  
  CONCLUSIONS
  Pupil responses to red and blue light stimuli weighted to favor cone or rod input are significantly reduced in patients with RP but are still recordable in patients having a non-recordable ERG. In addition, outer photoreceptor disease appears to unmask a post-illumination pupillary constriction to bright blue light, most likely mediated by intrinsic activation of melanopsin ganglion cells. Chromatic pupillometry provides a novel, noninvasive method for following retinal functional status, particularly in patients with severe RP and non-recordable ERG.
authors.affiliation: Department of Ophthalmology and Visual Science, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Randy
authors.initials: R
authors.lastname: Kardon
authors.forename: Susan C
authors.initials: SC
authors.lastname: Anderson
authors.forename: Tina G
authors.initials: TG
authors.lastname: Damarjian
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Grace
authors.forename: Edwin
authors.initials: E
authors.lastname: Stone
authors.forename: Aki
authors.initials: A
authors.lastname: Kawasaki
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D004596:Electroretinography; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D011680:Pupil / Q000502:physiology*; D012025:Reflex, Pupillary / Q000528:radiation effects*; D012174:Retinitis Pigmentosa / Q000503:physiopathology*; D014786:Vision Disorders / Q000503:physiopathology; D014794:Visual Fields / Q000502:physiology