title: Choroideremia: melanopsin-mediated postillumination pupil relaxation is abnormally slow.
abstract: OBJECTIVE
  To investigate the rod-cone and melanopsin pupillary light response (PLR) pathways in choroideremia.
  
  
  METHODS
  Eight patients with choroideremia and 18 healthy age-matched controls underwent chromatic pupillometry by applying blue (463 nm) and red light (643 nm) at 100 lux intensity to the right eye while recording pupil diameters. Absolute baseline pupil size (mm), normalized maximal pupil constriction and the early and late postillumination pupillary dilation, from 0 to 10 seconds and 10 to 30 seconds after the end of illumination, respectively, were determined. Postillumination responses to blue light were considered to be primarily driven by melanopsin activation of the intrinsic photosensitive retinal ganglion cells.
  
  
  RESULTS
  Baseline pupil diameters were comparable in patients with choroideremia and control subjects (p = 0.48). The maximum pupil constriction in patients with choroideremia was severely weakened in red light but only mildly weakened in blue light (p < 0.05). Postillumination dilation of the pupil was normal after red illumination but extremely protracted after blue illumination. Also, in contrast to healthy subjects, no abrupt change in the dilation curve was seen in the patients after the end of blue illumination, the early-phase dilation being completely abolished (p < 0.01).
  
  
  CONCLUSIONS
  Rod-cone-driven pupil responses were decreased as expected in an outer retinal degeneration, and near-normal pupil constriction in blue light supports that the melanopsin system is normal. In contrast, the lack of brisk early-phase dilation after blue illumination in choroideremia is remarkable and may be interpreted to mean that the absence of photoreceptor inhibition promotes a tonic contraction of the pupil.
authors.affiliation: Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Shakoor
authors.initials: S
authors.lastname: Ba-Ali
authors.affiliation: Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.
authors.forename: Søren Kirchhoff
authors.initials: SK
authors.lastname: Christensen
authors.affiliation: Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.
authors.forename: Birgit
authors.initials: B
authors.lastname: Sander
authors.affiliation: Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenberg
authors.affiliation: Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Larsen
authors.affiliation: Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Lund-Andersen
mesh_terms: D000328:Adult; D000368:Aged; D015794:Choroideremia / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015877:Miosis / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D010775:Photic Stimulation; D011446:Prospective Studies; D011680:Pupil / Q000502:physiology*; D012025:Reflex, Pupillary / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000378:metabolism* / Q000473:pathology / Q000528:radiation effects; D017299:Rod Opsins / Q000378:metabolism*; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: choroideremia; intrinsically photosensitive retinal ganglion cells; iris; melanopsin; postillumination pupillary response; pupillary light reflex; pupillometry