The Relation Between Light-Induced Lacrimation and the Melanopsin-Driven Postillumination Pupil ResponseLight-Induced Lacrimation and PIPR

摘要

Purpose:Toinvestigatethechromaticcharacteristicsandintensity-responsefunctionoflight-inducedreflexlacrimationanditscorrelationwiththemelanopsin-drivenpostilluminationpupilresponse(PIPR).Methods:Elevenvisuallynormalparticipantscompletedtheexperiment.Lacrimationwasmeasuredinoneeyebyplacingacalibratedfilterpaperstripintheconjunctivalsacovera1minute-interval(Schirmer'stest)duringwhichparticipantsreceivedeithernolightstimulation(baselinetrial)oroneflashofblueorredlightstimulipresentedbinocularlywithaGanzfeldstimulator,whilethepupilresponsewasrecordedsimultaneouslyfromthefelloweyebyusinganeyetracker.Lightstimulationtrialswerepresentedinalternatingfashionatsevenincrementalintensitysteps(0.1,1,3.16,10,31.6,100,and400cd/m2).Postilluminationpupilresponsewasdefinedasthemeanpupilconstrictionfrom10to30secondspostillumination.Results:Theamountoflacrimationinresponseto10to400cd/m2bluelightwassignificantlygreaterthanbaselineandincreasedmonotonicallywithincreasinglightintensity.Redlightdidnotinducesignificantreflexlacrimationuntilthebrighteststimulationat400cd/m2.TherewasapositivelinearcorrelationbetweenPIPRandlacrimationinresponsetobluelight(r=0.74,P0.001)butnottoredlight(r=0.13,P=0.25).Conclusions:Thechromaticcharacteristicsandintensity-responseoflight-inducedlacrimationarehighlyconsistentwiththefeaturesofmelanopsinphototransduction.Thisfindingisthefirstinvivoevidenceinhumans,supportingthehypothesisthatlight-inducedreflexlacrimationismediatedprimarilybymelanopsinphotoactivity,andprovidesnewinsightintotheputativemechanismsofphotophobia.