April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Full-Field Chromatic Pupillometry in the Assessment of the Post-Illumination Pupil Response Driven by Melanopsin-Containing Retinal Ganglion Cells
Author Affiliations & Notes
  • Shaobo Lei
    Program in Neuroscience and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
  • Herbert C Goltz
    Program in Neuroscience and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
    Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
  • Manokaraananthan Chandrakumar
    Program in Neuroscience and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
  • Agnes MF Wong
    Program in Neuroscience and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada
    Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
  • Footnotes
    Commercial Relationships Shaobo Lei, None; Herbert Goltz, None; Manokaraananthan Chandrakumar, None; Agnes Wong, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 4110. doi:https://doi.org/
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      Shaobo Lei, Herbert C Goltz, Manokaraananthan Chandrakumar, Agnes MF Wong; Full-Field Chromatic Pupillometry in the Assessment of the Post-Illumination Pupil Response Driven by Melanopsin-Containing Retinal Ganglion Cells. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4110. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: A sustained pupil constriction can be observed after the offset of a bright blue light stimulus. This post-illumination pupil response (PIPR) is produced by the intrinsically photosensitive melanopsin-containing retinal ganglion cells (ipRGCs), and can be measured by chromatic pupillometry. While chromatic pupillometry holds promise as a new diagnostic and outcome measurement tool to assess ipRGC function, current testing protocols use central-field stimulation and require a very bright light of long duration which can be difficult for some subjects. We test the hypothesis that a more robust PIPR can be induced with full-field blue light stimuli of shorter duration and lower intensity than with existing protocols.

Methods: Ten visually-normal adult subjects (mean age: 31 years, range 22 - 56) were tested. Pupil responses were recorded with an infrared eye tracker at 60 Hz. Full-field red (640±10 nm) and blue stimuli (467±17 nm) were presented in a darkened room using a Ganzfeld system. In experiment 1 (intensity trials), PIPR was induced using 1-second full-field stimuli of increasing intensity from 0.1 to 400 cd/m2 (11 steps). For comparison with a previously published protocol, a 60°×90° central-field blue stimulus at 400 cd/m2 was also presented for 1 second. In experiment 2 (duration trials), PIPR was induced using 100 and 400 cd/m2 full-field stimuli of increasing duration from 4 to 1000 ms (10 steps).

Results: PIPR increased monotonically with increasing stimulus intensity. Full-field stimulation using blue light at 400 cd/m2 intensity induced significantly more sustained PIPR than central-field stimulation (p = 0.001, post-hoc Student’s t-test). In addition, PIPR increased as the duration of stimulus increased from 4-200 ms; however, no further increase in PIPR was observed when the duration increased from 400-1000 ms.

Conclusions: Compared to existing central-field protocols, robust PIPR can be induced with a full-field protocol with lower intensity and shorter duration. This study is the first to demonstrate that saturating PIPR can be induced in vivo with a strong blue flash lasting only a few hundred milliseconds. This refined protocol will improve the recording quality and the subjective experience of future pupillometry testing.

Keywords: 667 pupil • 668 pupillary reflex • 648 photoreceptors  
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