LowVisionLigh+ng:ItsImportantBut
HowImportant?
GregoryL.Goodrich,Ph.D.
VisionRehabilita9onResearchConsultant
AERBVIConference2015
Norfolk,VA
Disclaimer&Acknowledgement
•  IwillspeakabouttheLuxIQfromJasperRidge.Iama
researchconsultantforJasperRidge.
•  Myresearchwasapprovedbyandconductedinaccordance
withregula9onsofVAPaloAltoResearchServiceandtheVA/
StanfordIns9tu9onalReviewBoard.
•  Apprecia9ontoPeterBorden,Ph.D.forcontentusedinthis
presenta9on.
Lightisreallyimportant
Light
Thereisan“op9mum”
Light
Whatis“op9mum”ligh9ng?
www.freshnessmag.com
•  Op9mumligh9ngisimportantinmaximizingvisualfunc9on
–  Formany,butnotall,lowvisionindividuals“more”lightisbeZer
•  mayadd~2linesofvisualacuity
–  Mayimprovethebenefitofop9calprescrip9on
•  Op9mumligh9ngvariesfrompersontoperson
–  Notsimply“more”light
–  Brightnessnotonlyfactor;color,colortemperature,glare,etc.
•  Aswithrefrac9ons,ligh9ngcanbemeasuredand
quan9fied
–  Needcalibrated,fast,easilyusedmeasurementtool
The“Curse”ofTerminology
Ididn’treallyunderstand
ligh9ngun9lIbeganto
understandthe
terminology.
Turnsoutitisn’tallthat
difficultonceyouhave
someclarifica9on.
Lux
?????
?
Volts
Candelas
??????
WhoneedsbeZerligh9ng?
•  Normallysighted
– 
– 
– 
– 
Readingindimlight
Threadingneedle
Workingin9ghtspaces
Etc.
•  Peoplewithvisualimpairments
–  Mostwithcentralfieldloss
–  Mostwithperipheralfieldloss
–  Somewithtrauma9cbraininjury
www.e-educa9on.psu.edu
•  BeZerlightinvolvesbrightness,color,glare,distribu9on
Wheredoweneedop9mizedligh9ng?
• 
• 
• 
• 
• 
ReadingpillboZles
Readingforwork,school,&enjoyment
Cooking&hobbies
Finances-wri9ngchecks&readingbills
Etc.
www.consumerreports.org
www.moneyandstuff.info
health.howstuffworks.com
www.pinterest.com
TaskvsAmbientLigh9ng
Taskligh9ng
Higherintensity
Localligh9ng
Op9mizedforacuity,task,
dura9on,comfort
Ambientligh9ng
Lowerintensity
Broadarealigh9ng
Op9mizedforsafety,mood
Myfocusisontaskligh9ng
pt.slideshare.net
Illuminancevs.Luminance
•  Illuminance:lighthi9ngthepage
lux(lumens/m2)orfoot-candles;
1footcandle=10lux
–  Usuallydiminisheswithdistanceandanglefromsource
–  Independentofsurfaceproper9es(color,finish,texture)
•  Luminance:lightcomingfromthepage
(candelaspersquaremeter,cd/m2)
www.klightlab.com
–  Dependsonsurfaceproper9essuchastexture,reflectance.
www.new-learn.info
Luminanceandilluminanceinvisiontes9ng
Luminance:Built-inlight
Illuminance–Reflectedlight
Rela9ng
luminanceandilluminance
•  Asasimpleruleofthumb,
•  Forareflec9vemaZesurface,
1candela/m2≈3lux(3lumens/m2)
•  Forexample,aback-liteyechartemits200cd/m2.
ThisisequivalenttotheilluminanceonawhitemaZeeye
chartina600luxexamroom.
=
Commonilluminancevalues
Starlight
.0001lux
Fullmoon
.27–1lux
Generalresiden9alligh9ng
50–100lux
Verydarkovercastday
100lux
Residen9aldiningroom
100–200lux
Residen9alreading
200–500lux
www.ltlmagazine.com
Classroom,brightlitexamroom500–1,000lux
Overcastday
1,000lux
Fulldaylight
10,000–100,000lux
Source:ReaMS.Ligh@ngHandbook:[email protected]:
Illumina9ngEngineeringSocietyofNorthAmerica;1993;Wikipedia
Measurementofligh9ng
•  Lightmetersmeasure
illuminanceineither
–  Lux,or
–  Footcandles
•  Rela9velyinexpensive
–  ~$30.00andup
Illuminanceandangle
•  Illuminancedependsonanglebetweenlightsourceand
reflec9ngsurface.Thelowertheanglethelowerthe
illuminance.
Textfacingsource:higherilluminance
Source
Textatangleincreasesarea:
lowerilluminance
Keyproper9es:Color
•  Colorarisesfromthemixofwavelengthsinthesourcelight
•  Monochroma9clighthasonewavelength:
–  Green=~527nm
–  Red=~630nm
•  Mixingcolorscreateshues
(Moreonthislater)
Keyproper9es:Contrast
•  Contrast=differencebetweenbackgroundandtext
•  100%contrastispureblackonpurewhite
•  Eyechartsouenhave80%contrastwhilemanyreading
materialshavelowcontrast
•  Contrastisapropertyofthemedium-ligh9ngorfiltersdo
notchangeit.
The Daily
Mar+ansinvadeearth
Contrast
•  Commondefini9onis:
RMAX − RMIN
Contrast =
RMAX + RMIN
–  Perfectlywhitepagewithblacktesthascontrastof1or100%
–  Anewspapermighthavedarkgreyprint(75%reflec9on)onlightgrey
paper(15%)yieldingacontrastof67%
•  Ligh9ngorfiltersdonotchangecontrast!
Keyproper9es:Glare
•  Unwantedlightfromwindow,lamp,reflec9ons,orthepage
itself.
•  Glarecanbedifficulttocontrolwhenprovidingbrightlight.
Glare:Reducesperceivedcontrast
•  Ligh9ngdoesnotchangeactualcontrast,butreduces
re9nal(perceived)contrast
Luminance
120
100
30
20
10
Text
Page
Noglare
Contrast=
(100–10)/(100+10)=82%
Text
Glare
Page
Contrast=
(120–30)/(120+30)=60%
Glare:Example
Clockonnightstand
without(clockfacevisible)
Andwithbrightglaresource
(clockfacenotvisible)
Awaytoreduceglare
Brightness:Steven’sPowerLaw
Theeye’ssensa9onofhigherintensitydecreasesas
theintensityincreases.
Onlylargechangesinbrightnessareeffec9ve.
Thismayincreaseglareunlessligh9ngiscarefully
Sensa9on
controlled.
Example:
3-waybulbwith50,100and150waZsoutput.
Thedifference,50waZs,isthesamebetweeneachseyng.
0to50waZsismoreno9ceablethan100to150waZs.
Schwartz,VisualPercep9on,4thedi9on
Intensity
Warmandcoolwhite
“Warm”hasmorered
“Cool”hasmoreblue
Lightshavea(non-intui9ve)color
temperature(oKelvin)
•  Thehigherthetemperaturethecoolerthelightcolor)
Warmer
Cooler
AMDandmorelight
•  Mostnormallysightedfolkreachpeakacuityat500lux
(normaltaskligh9ng).**
•  AMDpa9entsmayneed>4Xor2000luxtoachievepeak
acuity.
•  Mostpreferbrighterlight
**Moreaboutthislater–ligh9ngto
maximizeacuityandpreferredligh9ng
forreadingaredifferent.
www.pinterest.com
WBRCStudy
•  Designedtocomparevisualacuity(highandlowcontrast)for
normalsandlowvisionpa9ents
•  Comparedacuitymeasuredintheclinicwiththatobtained
usingtheLuxIQ
–  Subjectsset:
•  Brightness
•  Colortemperature
•  Counterbalancedorderofpresenta9on
WBRCStudypar9cipants
Controls(N=10)
SubjectsN=30)
MeanAge
55.5yrs.(40-68)
70.7yrs.(51-90)*
WorkingDistance
44.7in.(32-56cm)
26.3in.(12-45cm)**
•  Controlssignificantlyyoungerthansubjects
•  Controlsusedsignificantlygreaterworkingdistances
•  Subjectshadvarietyofpathologies
•  AMD=8
•  Glaucoma=8
•  OtherTBI(hemianopia),NAION,diabe9cre9nopathy,trauma/TBI,
inters99alkera99s,CRAO,andmacularedema
•  Controlspreferredgreaterbrightnessthansubjects
•  Subjectsusedbestnearcorrec9onforallcondi9ons
Ligh9ngmeasurementtools:LuxIQ
•  Leuslidercontrolsbrightness
–  0to5,000lux
•  Rightslidercontrolscolor
temperature
–  2,700to6,300oK
•  Slidersmoveleutorightto
increasebrightness/color
temperature
•  Readingsfromscalesabove
sliders
•  Colenbranderhigh/low
contrastnearacuitychart
•  RecordednumberofleZers
read
Controlledstudyofbrightnessandcolor
temperature
•  Controlspreferred
significantlybrighterlight
–  Controls:500–5000lux
–  Subjects:700–5000lux
•  Nosignificantdifference
betweennormaland
controlpopula9onsoncolor
temp.
–  Controls:2700–5500oK
–  Subjects:2700–6500oK
5000
4500
4260
4400
4000
3500
3000
2500
2000
2825
Controls
1954
Subjects
1500
1000
500
0
Brightness
ColorTemp.
500lux=valuewherenormallysightedreach
asymptoteforvisualacuity
NumberofleZersread
70
•  MaximumleZers=65
•  Nosignificantchangefor 60
controls
•  Comparedtoclinic
50
illumina9onsubjectsread
40
significantlygreater
numberofcharacterson
bothhighandlowcontrast 30
charts
•  Gainvariedbysubjectfrom 20
noaddi9onalleZerstoover
10
2lines
*
*
*
*
0
ControlsHigh
ControlsLow
SubjectsHigh
SubjectsLow
Clinic
LuxIQwhite
LuxIQTemp
StudyConclusions
•  Bothcontrolsandsubjectspreferredbrightlight(controls
significantlymore)
•  Controlsandsubjectsverysimilarinpreferredcolortemperature
•  Brightnessandcolortemperaturesignificantlyimprovednumber
ofleZersreadonhighcontrastforsubjectsbutnotcontrols
•  Brightnessandcolortemperatureeachsignificantlyimproved
numberofleZersreadonlowcontrastforsubjectsbutnot
controls
•  Op9mizedligh9ngenhancedeffec9venessoflowvision
prescrip9on
•  Lowvisionindividualsusingop9mizedligh9ngreadsmallerprint;
op+mizedligh+ng=magnifica+on
Caveats
•  Notallsubjectspreferredorbenefitedfrombrighterlight
–  EvenamongAMDpa9entswhoarethoughttoneedmorelight
•  Preferenceforligh9ngisindividualforbothcontrolsandlow
visionsubjects
•  Individualmeasurementandprescrip9onofligh9ngshould
improvelowvisionindividual’sperformanceonneartasks
Relatedstudies
•  RotruckandFletcher(ARVO2015)
–  POAGpa9entsprefersignificantlylesslightthanAMDpa9ents
•  POAG2,345lux(±922);AMD4,289lux(±713)
–  Op9mumligh9ngsignificantlyimprovesacuity
Hicontrast 1.8M
Lowcontrast 6.6M
Room(500lux)
1.2M
5.2M
Op9mum
Prescribingligh9ng
•  Currentstandardistrialanderrorlackingsystema9c,
calibratedbasis
Swappingbulbs
…orlamps
•  LuxIQoffersacalibratedop9on
–  Ithasbeenshowntoimproveacuityandmayimprovevisual
comfortforlowvisionreaders.
Nextsteps
•  I’macardcarryingresearchersoofcourseI’mgoingtotell
youmoreresearchisneeded
–  Doesop9mumligh9ngimprovereadingdura9on?
–  Doesimprovementtranslatetoothertasks?
–  Studiesdonearewithadults,doesthebenefittranslatetochildren?
•  StudywithchildrenwithCVIstar9ngupatCaliforniaSchoolfortheBlind
(Marasch,Lueck,&Goodrich)
–  LuxIQ2mayprovidecalibratedtoolforprescribing9nts/filters?
ResearchFindingsReferences
(availableatwww.jasperridge.net)
•  AAO2013
–  Quan9fyingPa9entLigh9ngNeedstoImproveLowVisionClinical
Prac9ceandPa9entPerformance-GregoryL.Goodrich,ShanidaIngalla,
MeganDolkas
•  Envision2014
–  IsLowVisionLigh9ngComingofAge-GregoryL.Goodrich,Donald
Fletcher,KarenKendrick,FaydimRassamdana
–  Measuringandprescribingpreferredlightintensityandcolor-Peter
Borden,MicheleKlein
•  ARVO2015
–  Pa9entswithAMDandPOAGmayrequiredifferentligh9ngtomaximize
visualacuity-JillRotruck,DonFletcher;LauraWalker
–  Func9onalImpactofTaskLigh9ngonReadingwithLowVision-TonyA.
Succar,LauraWalker,KarenKendrick,AndraMies,DonaldC.Fletcher
Ques9ons?
Thankyou!
ContactInforma9on:[email protected]