Effects of selective-wavelength block filters on pupillary light reflex under red and blue light stimuli.
OBJECTIVE
To investigate at which wavelength melanopsin-containing retinal ganglion cells (mRGCs) depolarize and how they affect pupillary constriction induced by light stimulation in humans.


METHODS
The pupil light reflex was evaluated for 30 normal subjects by use of an infrared pupillometer. Blue light stimulation (470 nm) and red light stimulation (635 nm) of 100 cd/m(2) were selected. Selective-wavelength block filters which can selectively remove the wavelengths 440 and 470 nm were used. Visual tests were also performed to observe the effects of the filters on visual acuity, color vision, and contrast sensitivity.


RESULTS
The pupil transiently constricts and then settles toward a steady-state diameter when stimulated with the light. When the 470-nm-block filter was worn, the sustained phase of pupillary constriction, thought to be mediated by the mRGCs, was not stable but there was no effect on the initial phase of pupillary constriction under blue light stimulation. Visual acuity, color vision, and contrast sensitivity were not affected by the 470-nm-block filter.


CONCLUSIONS
These results suggest that the mRGC in humans may respond to 470-nm-wavelength light at 100 cd/m(2), and there is a possibility of affecting the sustained phase of the light reflex without changing visual performance.
School of Allied Health Sciences, Kitasato University, 1-15-1 Kitasato, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan. hitoshi@e03.itscom.net
Hitoshi
H
Ishikawa
Asami
A
Onodera
Ken
K
Asakawa
Satoshi
S
Nakadomari
Kimiya
K
Shimizu
D015350:Contrast Sensitivity / Q000502:physiology; D006801:Humans; D008027:Light; D011680:Pupil / Q000502:physiology*; D012025:Reflex, Pupillary / Q000528:radiation effects*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D017299:Rod Opsins / Q000378:metabolism; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult; D000099210:Melanopsin
D017299:Rod Opsins; D000099210:Melanopsin