arvo poster 2014 shaobo v3
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Melanopsin is a photopigment allowing a small subset of retinal ganglion cells to absorb light energy directly and fire
action potential with or without synaptic input form rods and
cones. Intrinsic photo response of melanopsin-containing
retinal ganglion cells (MGCs) provides sustained irradiance
coding for non-visual photoperception functions including
circadian photoentrainment and the pupillary light response.
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 MGC, and can be
measured by chromatic pupillometry. Measuring PIPR holds
promise as a novel tool to assess MGC 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 consistent
PIPR can be induced with full-field blue light stimuli of
shorter duration and lower intensity than with central-field
Full-field and central-field light stimulation were presented
with a Colordome Ganzfeld bowl originally designed for
Pupillary light response was monitored with a video based
eye tracker at 60Hz.
Experimental Conditions (cont.):
For each of the intensity and duration steps, a red flash was
presented first followed by a blue flash 45 s after the offset of
the red flash. Participants were provided with a short break at
45 s after the offset of the blue flash to allow the pupil size to
return to baseline and to prevent fatigue.
Measurement and Data Analysis:
Pupil size data were normalized to baseline calculated from
the mean pupil size during a 1 s period before the onset of
Primary Outcome Measure
PIPR: mean of the normalized pupil size over a 20 s period
from 10-30s after the offset of light stimuli (smaller number
means greater pupil constriction).
400 cd/m2, full-field blue stimulus induced significantly
larger PIPR than central-field blue stimulus of the same
PIPR to red flashes did not differ significantly full-field vs.
No further increase in PIPR was observed when the
duration increased from 400-1000 ms.
400-1000 ms, 400 cd/m2 blue full-field stimuli induced
significantly greater PIPR than 1000 ms blue central-field
stimulus of the same duration.
Full-field stimulation is more effective that central-field
stimulation in inducing PIPR, suggesting that PIPR is a
function of stimulus intensity, duration and area.
This study is the first to demonstrate that saturating PIPR
up to 30 seconds post illumination can be induced in vivo
with a strong blue flash lasting only a few hundred
This updated understanding of the relation between PIPR
and stimulus intensity, duration and area will allow
investigators to tailor their PIPR testing paradigm to target
a specific research question, and greatly facilitate the
development of a convenient and comfortable technique to
assess MGCs function for emerging clinical use.
Contact InformationContact Information
FullFull--Field Field ChChroromamatictic Pupillometry in the Assessment of the PostPupillometry in the Assessment of the Post--Illumination Pupil ResponseIllumination Pupil Response
Driven by MelanopsinDriven by Melanopsin--Containing Retinal Ganglion CellsContaining Retinal Ganglion Cells
1Shaobo Lei, 1,2H.C. Goltz, 1M. Chandrakumar, 1,2,3A.M.F. Wong
1Program in Neuroscience & Mental Health, Hospital for Sick Children; Department of Ophthalmology and Vision Sciences, 2University of Toronto & 3Hospital for Sick Children, Toronto Canada
No.4110 - A0098
10 visually-normal adult subjects (mean age: 31 years,
range 22 56), only right eyes were stimulated and
recorded, left eyes were patched during recording.
Experiment 1 (intensity trials): After 10 min dark adaptation,
PIPR was induced with alternating red (64010 nm) and
blue (46717 nm), 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 6090 central-field
blue stimulus at 400 cd/m2 was also presented for 1 second.
Experiment 2 (duration trials): 10 min dark adaptation, 100
cd/m2 and 400 cd/m2, red and blue full-field stimulations of
increasing duration from 4-1000 ms were presented
alternately. 100 cd/m2 and 400 cd/m2 trials were conducted
on different days.
* Mean (n=10) normalized post-illumination pupil response (PIPR) tracings in response to 1 s stimulation of varying intensity from 10 visually-normal participants.
PIPR to full-field blue stimulation increased monotonically
with increasing stimulus intensity.
Red light (internal reference) induced no or minimal PIPR
at all intensity level.
Results: Results: Experiment 1 (intensity Experiment 1 (intensity trials)trials)
* Comparison of PIPR induced using 400 cd/m2 central-field stimuli (dashed line) vs 100-400 cd/m2 full-field stimuli (solid lines)
PIPR in response to 400 cd/m2 increased as the duration of
stimulus increased from 4-200 ms.
* Mean PIPR to 100 cd/m2 and
400 cd/m2 full-field stimulation
of varying duration from 10
Results: Results: Experiment 2 (duration trials)Experiment 2 (duration trials)
* comparison of PIPR to full-field blue stimuli of 400 cd/m2 intensity of the 6 longest duration steps (100, 200, 400, 600, 800, and 1000 ms.
*Authors have no commercial interest to disclose.
One-way ANOVA with post hoc corrected for pairwise
multiple comparisons using the TukeyKramer method.
Full-Field vs. Central-field Stimulation
* Intensity-response function of PIPR to full-field stimulation vs. PIPR to 1s, 400 cd/m2 central-field stimuli
* Duration-response function of PIPR to full-field stimulation vs. PIPR to 1s, 400 cd/m2 central-field stimuli