LowVisionLigh+ng:ItsImportantButHowImportant?

GregoryL.Goodrich,Ph.D.VisionRehabilita9onResearchConsultant

AERBVIConference2015

Norfolk,VA

Disclaimer&Acknowledgement

•  IwillspeakabouttheLuxIQfromJasperRidge.IamaresearchconsultantforJasperRidge.

•  Myresearchwasapprovedbyandconductedinaccordancewithregula9onsofVAPaloAltoResearchServiceandtheVA/StanfordIns9tu9onalReviewBoard.

•  Apprecia9ontoPeterBorden,Ph.D.forcontentusedinthispresenta9on.

Lightisreallyimportant

Light

Thereisan“op9mum”

Light

Whatis“op9mum”ligh9ng?

•  Op9mumligh9ngisimportantinmaximizingvisualfunc9on–  Formany,butnotall,lowvisionindividuals“more”lightisbeZer

•  mayadd~2linesofvisualacuity

–  Mayimprovethebenefitofop9calprescrip9on

•  Op9mumligh9ngvariesfrompersontoperson–  Notsimply“more”light–  Brightnessnotonlyfactor;color,colortemperature,glare,etc.

•  Aswithrefrac9ons,ligh9ngcanbemeasuredandquan9fied–  Needcalibrated,fast,easilyusedmeasurementtool

www.freshnessmag.com

The“Curse”ofTerminology

Ididn’treallyunderstandligh9ngun9lIbegantounderstandtheterminology.Turnsoutitisn’tallthatdifficultonceyouhavesomeclarifica9on.

Lux??????

Candelas

Volts

??????

WhoneedsbeZerligh9ng?

•  Normallysighted–  Readingindimlight–  Threadingneedle–  Workingin9ghtspaces–  Etc.

•  Peoplewithvisualimpairments–  Mostwithcentralfieldloss–  Mostwithperipheralfieldloss–  Somewithtrauma9cbraininjury

•  BeZerlightinvolvesbrightness,color,glare,distribu9on

www.e-educa9on.psu.edu

Wheredoweneedop9mizedligh9ng?

health.howstuffworks.com

www.consumerreports.org

•  ReadingpillboZles•  Readingforwork,school,&enjoyment•  Cooking&hobbies•  Finances-wri9ngchecks&readingbills•  Etc.

www.pinterest.com

www.moneyandstuff.info

TaskvsAmbientLigh9ng

Taskligh9ngHigherintensityLocalligh9ngOp9mizedforacuity,task,dura9on,comfort

Ambientligh9ngLowerintensityBroadarealigh9ngOp9mizedforsafety,mood

Myfocusisontaskligh9ng

pt.slideshare.net

Illuminancevs.Luminance

•  Illuminance:lighthi9ngthepagelux(lumens/m2)orfoot-candles;1footcandle=10lux–  Usuallydiminisheswithdistanceandanglefromsource–  Independentofsurfaceproper9es(color,finish,texture)

•  Luminance:lightcomingfromthepage(candelaspersquaremeter,cd/m2)–  Dependsonsurfaceproper9essuchastexture,reflectance.

www.klightlab.com

www.new-learn.info

Luminanceandilluminanceinvisiontes9ng

Luminance:Built-inlight Illuminance–Reflectedlight

Rela9ngluminanceandilluminance

•  Asasimpleruleofthumb,•  Forareflec9vemaZesurface,

1candela/m2≈3lux(3lumens/m2)•  Forexample,aback-liteyechartemits200cd/m2.

ThisisequivalenttotheilluminanceonawhitemaZeeyechartina600luxexamroom.

=

Commonilluminancevalues

Starlight .0001luxFullmoon .27–1luxGeneralresiden9alligh9ng 50–100luxVerydarkovercastday 100luxResiden9aldiningroom 100–200luxResiden9alreading 200–500luxClassroom,brightlitexamroom500–1,000luxOvercastday 1,000luxFulldaylight 10,000–100,000lux

www.ltlmagazine.com

Source:ReaMS.Ligh@ngHandbook:ReferenceandApplica@on.NY:Illumina9ngEngineeringSocietyofNorthAmerica;1993;Wikipedia

Measurementofligh9ng

•  Lightmetersmeasureilluminanceineither–  Lux,or–  Footcandles

•  Rela9velyinexpensive–  ~$30.00andup

Illuminanceandangle

•  Illuminancedependsonanglebetweenlightsourceandreflec9ngsurface.Thelowertheanglethelowertheilluminance.

Textatangleincreasesarea:lowerilluminance

SourceTextfacingsource:higherilluminance

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:

–  Perfectlywhitepagewithblacktesthascontrastof1or100%–  Anewspapermighthavedarkgreyprint(75%reflec9on)onlightgrey

paper(15%)yieldingacontrastof67%

•  Ligh9ngorfiltersdonotchangecontrast!

Contrast = RMAX − RMINRMAX + RMIN

Keyproper9es:Glare

•  Unwantedlightfromwindow,lamp,reflec9ons,orthepageitself.

•  Glarecanbedifficulttocontrolwhenprovidingbrightlight.

Glare:Reducesperceivedcontrast

•  Ligh9ngdoesnotchangeactualcontrast,butreducesre9nal(perceived)contrast

NoglareContrast=(100–10)/(100+10)=82%

GlareContrast=(120–30)/(120+30)=60%

102030

100120

Luminance

Text Page Text Page

Glare:Example

Clockonnightstandwithout(clockfacevisible)

Andwithbrightglaresource(clockfacenotvisible)

Awaytoreduceglare

Brightness:Steven’sPowerLaw

Theeye’ssensa9onofhigherintensitydecreasesastheintensityincreases.Onlylargechangesinbrightnessareeffec9ve.Thismayincreaseglareunlessligh9ngiscarefullycontrolled.Example:3-waybulbwith50,100and150waZsoutput.Thedifference,50waZs,isthesamebetweeneachseyng.0to50waZsismoreno9ceablethan100to150waZs.Schwartz,VisualPercep9on,4thedi9on

Intensity

Sensa9on

Warmandcoolwhite

“Warm”hasmorered “Cool”hasmoreblue

Lightshavea(non-intui9ve)colortemperature(oKelvin)

•  Thehigherthetemperaturethecoolerthelightcolor)

Warmer

Cooler

AMDandmorelight

•  Mostnormallysightedfolkreachpeakacuityat500lux(normaltaskligh9ng).**

•  AMDpa9entsmayneed>4Xor2000luxtoachievepeakacuity.

•  Mostpreferbrighterlight

www.pinterest.com

**Moreaboutthislater–ligh9ngtomaximizeacuityandpreferredligh9ngforreadingaredifferent.

WBRCStudy

•  Designedtocomparevisualacuity(highandlowcontrast)fornormalsandlowvisionpa9ents

•  ComparedacuitymeasuredintheclinicwiththatobtainedusingtheLuxIQ–  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)**

64.6 65.0 64.9 65.0

63.3 64.6 64.7 65.0

42.547.7 47.9* 50.5*

25.9

30.1* 33.1*35.4*

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Clinic LuxIQ-White LuxIQ-Temperature

LuxIQ-Green

NofC

haractersR

ead

ControlsHigh

ControlsLow

SubjectsHigh

SubjectsLow

64.6 65.0 64.9 65.0

63.3 64.6 64.7 65.0

42.547.7 47.9* 50.5*

25.9

30.1* 33.1*35.4*

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Clinic LuxIQ-White LuxIQ-Temperature

LuxIQ-Green

NofC

haractersR

ead

ControlsHigh

ControlsLow

SubjectsHigh

SubjectsLow

•  Controlssignificantlyyoungerthansubjects•  Controlsusedsignificantlygreaterworkingdistances•  Subjectshadvarietyofpathologies

•  AMD=8•  Glaucoma=8•  OtherTBI(hemianopia),NAION,diabe9cre9nopathy,trauma/TBI,

inters99alkera99s,CRAO,andmacularedema•  Controlspreferredgreaterbrightnessthansubjects•  Subjectsusedbestnearcorrec9onforallcondi9ons

Ligh9ngmeasurementtools:LuxIQ

•  Leuslidercontrolsbrightness–  0to5,000lux

•  Rightslidercontrolscolortemperature–  2,700to6,300oK

•  Slidersmoveleutorighttoincreasebrightness/colortemperature

•  Readingsfromscalesabovesliders

•  Colenbranderhigh/lowcontrastnearacuitychart

•  RecordednumberofleZersread

Controlledstudyofbrightnessandcolortemperature

•  Controlspreferredsignificantlybrighterlight–  Controls:500–5000lux–  Subjects:700–5000lux

•  Nosignificantdifferencebetweennormalandcontrolpopula9onsoncolortemp.–  Controls:2700–5500oK–  Subjects:2700–6500oK 500lux=valuewherenormallysightedreach

asymptoteforvisualacuity

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Brightness ColorTemp.

Controls

Subjects

2825

1954

42604400

NumberofleZersread

0

10

20

30

40

50

60

70

ControlsHigh ControlsLow SubjectsHigh SubjectsLow

Clinic

LuxIQwhite

LuxIQTemp

*•  MaximumleZers=65•  Nosignificantchangefor

controls•  Comparedtoclinic

illumina9onsubjectsreadsignificantlygreaternumberofcharactersonbothhighandlowcontrastcharts

•  Gainvariedbysubjectfromnoaddi9onalleZerstoover2lines

*

**

StudyConclusions

•  Bothcontrolsandsubjectspreferredbrightlight(controlssignificantlymore)

•  Controlsandsubjectsverysimilarinpreferredcolortemperature•  Brightnessandcolortemperaturesignificantlyimprovednumber

ofleZersreadonhighcontrastforsubjectsbutnotcontrols•  Brightnessandcolortemperatureeachsignificantlyimproved

numberofleZersreadonlowcontrastforsubjectsbutnotcontrols

•  Op9mizedligh9ngenhancedeffec9venessoflowvisionprescrip9on

•  Lowvisionindividualsusingop9mizedligh9ngreadsmallerprint;op+mizedligh+ng=magnifica+on

Caveats

•  Notallsubjectspreferredorbenefitedfrombrighterlight–  EvenamongAMDpa9entswhoarethoughttoneedmorelight

•  Preferenceforligh9ngisindividualforbothcontrolsandlowvisionsubjects

•  Individualmeasurementandprescrip9onofligh9ngshouldimprovelowvisionindividual’sperformanceonneartasks

Relatedstudies

•  RotruckandFletcher(ARVO2015)–  POAGpa9entsprefersignificantlylesslightthanAMDpa9ents

•  POAG2,345lux(±922);AMD4,289lux(±713)

–  Op9mumligh9ngsignificantlyimprovesacuityHicontrast 1.8M 1.2MLowcontrast 6.6M 5.2M

Room(500lux) Op9mum

Prescribingligh9ng

•  Currentstandardistrialanderrorlackingsystema9c,calibratedbasis

•  LuxIQoffersacalibratedop9on–  Ithasbeenshowntoimproveacuityandmayimprovevisual

comfortforlowvisionreaders.

Swappingbulbs …orlamps

Nextsteps

•  I’macardcarryingresearchersoofcourseI’mgoingtotellyoumoreresearchisneeded–  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

–  Pa9entswithAMDandPOAGmayrequiredifferentligh9ngtomaximizevisualacuity-JillRotruck,DonFletcher;LauraWalker

–  Func9onalImpactofTaskLigh9ngonReadingwithLowVision-TonyA.Succar,LauraWalker,KarenKendrick,AndraMies,DonaldC.Fletcher

Ques9ons?

Thankyou!

ContactInforma9on:Greg.Goodrich@yahoo.com