title: Dark adaptation-induced changes in rod, cone and intrinsically photosensitive retinal ganglion cell (ipRGC) sensitivity differentially affect the pupil light response (PLR).
abstract: OBJECTIVE
  Our purpose was to explore pupil light response (PLR) with respect to the change in sensitivity of photoreceptors during various dark adaptation phases and to determine the optimal duration of dark adaptation time before the PLR.
  
  
  METHODS
  The PLR was recorded in 15 healthy subjects and three patients with neural or retinal vision loss after 1-sec blue and red light stimuli of 1, 10, and 100 cd/m(2). The PLR was repeated nine times at different checkpoints during the 40-minute dark adaptation. The transient contraction amplitude, sustained contraction amplitude, and relative sustained contraction ratio of the PLR were analyzed.
  
  
  RESULTS
  The increase in the transient contraction amplitude during the entire dark adaptation process was significant (changing up to 45.1 %) in the initial phase of dark adaptation under different stimulus conditions. The changes in the sustained contraction amplitude and the relative sustained contraction ratio were substantial (changing up to 71.0 % and 37.2 % from 1 to 20 minutes of dark adaptation, respectively) under high-intensity blue illumination. The inflection point of the contraction curves in the dark adaptation was 15 or 20 minutes. The patients' PLR results changed in a similar manner.
  
  
  CONCLUSIONS
  The changes in the sensitivity of different photoreceptors occurred at different rates, and the contraction amplitude of the PLR was significantly affected by the dark adaptation duration. So 20 minutes of dark adaptation before PLR testing was suggested to achieve a consistent and stable pupil response. The dark adaptation effect should be put into consideration when comparing the results from different phases of the PLR test.
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Bin
authors: B
authors: Wang
authors: College of Electronics and Control Engineering, Chang'an University, Xi'an, Shaanxi, China.
authors: Chao
authors: C
authors: Shen
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Lei
authors: L
authors: Zhang
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Linsong
authors: L
authors: Qi
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Lu
authors: L
authors: Yao
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Jianzhang
authors: J
authors: Chen
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Guoqing
authors: G
authors: Yang
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032.
authors: Tao
authors: T
authors: Chen
authors: Department of Aerospace Medicine, the Forth Military Medical University, Xi'an, Shaanxi, China, 710032. zhangzm@fmmu.edu.cn.
authors: Zuoming
authors: Z
authors: Zhang
mesh_terms: D000328:Adult; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D005901:Glaucoma / Q000503:physiopathology; D006801:Humans; D008027:Light; D008297:Male; D008875:Middle Aged; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D011680:Pupil / Q000528:radiation effects; D012025:Reflex, Pupillary / Q000502:physiology*; D012164:Retinal Diseases / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012167:Retinal Perforations / Q000503:physiopathology; D012174:Retinitis Pigmentosa / Q000503:physiopathology; D017299:Rod Opsins / Q000502:physiology; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: Dark adaptation; Intrinsically photosensitive retinal ganglion cell (ipRGC); Melanopsin; Monochromatic light; Photoreceptors; Pupil contraction; Pupil light response (PLR); Pupillometry