PEDIATRICs. eye growth and development

pediatric optometry

1. DevelopmentofEye
•eyebeginstodevelopasapairofopticvesiclesoneachsideofforebrainattheendof4thweekofpregnancy.
•Opticvesiclesareoutgrowingsofthebrainwhichmakecontactwiththesurfaceectodermandthiscontact
induceschangesnecessaryforfurtherdevelopmentoftheeye.
•Throughagrooveatthebottomoftheopticvesicleknownaschoroidfissurethebloodvesselsentertheeye.
SurfaceEctoderm
•Lens
•cornealepithelium
Neuralcrest
Betweensurfaceectoderm&neuroectoderm
Neuralcrestcellsarederivedfromtheectodermandlieclosetotheneuraltube&form:
•Sclera
•Cornealstroma&endothelium
•Connectivetissue&bonystructureoftheorbit
Mesoderm
Liescloselytoneuralcrest,babawniya
•Extraocularmuscles
•Endothelialliningofbvoftheeye
•Sclera&choroid
NeuralTubeEctoderm(Neuroectoderm)-everythingfromneuralpathariseshere
•Retina
•EpithelialliningofCiliarybody&Iris
•Opticnerves
•Vitreous
ROP2predisposingfactors:
-#ofgestationalweeks(7mos/<37weeks)
-weight<2.1kg
InROP,there’slackofbloodsupply,brainwillsendsignaltomakeabnormalnewbloodvesselstomakeenough
bloodsupply,thisabnormalnewBVareweak&willleak,leadingtohemorrhage,&causeretinopathy.
PhysicalConditionOfTheEyeBeforeAndAfterBirth
Intrauterine
Eyelidsarenotfullyseparated.
Pupildoesn’tconstrict/dilate;theaqueousdrainagesystemmaynotbefullyfunctional.
Choroidlackspigment.
Retinalbvareimmature.
Opticnervenotmyelinated.(cantconductimpulse,orcantprocessinfo)
Lackofabilitytocontrollightenteringtheeye,visualsystemisnotreadytofunction.
AtBirth
Iriseshaveagray/bluishappearance;naturalcolordevelopsaspigmentforms.
Eyes'pupilsarenotabletodilatefullyyet
Curvatureoflensisnearlyspherical
Retinanotfullydeveloped
•Infants'eyesdevelopsignificantlyafterbirth.Themusclesoftheeye(ciliarymuscles)–becomestrongerafter
2mosofage,allowinginfantstofocusonparticularobjectsthrucontraction&relaxation.
Axiallength
•distancefromcorneatotheretinais16–17mmatbirth
•20-21mmat1year
•23–25mminadulthood
•Retinalimagesarealsosmallercomparedtoadultsduetoshorterdistancesfromretinatocornea.
Orbit,Lid&Adnexa
•Volumedoublesbyage1yr(10.3-22.3cu.mm)39.1byage6(adult59.2cu.mm)
•Palpebralfissurewidthislessascomparedtoverticaldimension(ovalappearance)
•Excretory&secretoryfunctionarepresent
•itisproventhat80%ofinfanthavenormalbasistearsecretionduringfirst2daysoflife
Conjunctiva
•Conjunctivainchildrenisthicker&tougher(duetolotsofepithelialcells)
•Conjunctivalsacisusuallysterileatbirth.
Cornea
•Changesinthefirstfewyearsincludeenlargement,flattening,thinning,&increasedtransparency.
•Cornealdiameteratbirth:horizontal9.8mm&vertical10.4mm
•Investigationsrecommendedifcornealdiameterof<9mmor>11mmisfoundinnewborn.
•Corneais0.96mmthickincenter&becomes0.52mmthickerbyage6mos.(corneabecomesflattergrowing)
•Peripheralthicknessis1.2mm.
•Cornealpower51.2D---43.5D(atbirthshapeofeyeballissphericalsocorneaissteeper,highpower)
Iris&pupil
•Iriscolorchanges&becomespermanentduringthefirst6mos.
•Newborn'spupilgrowsfrom2.2mmtoadult3.3mm.(3-4mmisaccpted,>5mmdilated,<3mmconstricted)
•Pupilissmall,meandiameteris3.6mmduetoconstantsleep&poorlydevelopeddilatormuscle.
•Abnormalpupilsizeininfantsis<1.8mm&>5.2mm.
•Pupillaryresponseby31weeksofgestationispositive.
Anteriorchanberangle&IOP
•Angleisshallow(sincehyperopic)&iris&ciliaryareinsertedposteriorly.
•MeanIOPis9.52+-2.66mmofHg.(adultnormaliop10-21mmHG)
Lens
•Crystallinelensw/45Dduringinfancy,losesabout20Dofpowerby6y/o
•Refractiveindexoflensalsodecreases.
•Lensthicknessincreasestoamaxat10weeks&thendecreases.
•1-2y/ohadthinnerlensesthanthoseof1-4daysold.
•thinningoflensby0.5mmbetweenbirth&13y/ow/60%occurringbefore3y/o
Retina
•Maculaisleastdevelopedatbirth
•Macularpigmentationappearsby34-35weeksgestation.
•Fovealreflexispresentby37weeksgestation.
•Fovealregiongetsthinner(1000лm-700лm)by4yrs.
•Conesdensity/areaincreasesbyage.
•Peripheralretinadevelopfasterthanfovealarea.

2. •Retinacontainsmostlyrodcells(motiondetection,peripheral,nightvision)
•1mospostnatal-Conecellsappearbutnotcompactlyarrange(colorperception,centralvision,recognition)
•8mospostnatal-Maculaismature
VISUALDEVELOPMENT
-Visualdevelopmentinachildisaverycomplexprocessstartingatanembryoageof18days.
-Itisacompositefunction(motorsystem,physiologicaldevelopment,corticaldevelopment)
Visualdevelopmentcanbroadlybedividedinto:
-Anatomical
-Oculomotor(incoordinationwithvestibulardevelopment)
-Physiological(visualacuity,accommodation,binocularity,ocularmovements,colorperception)
Allthesefactorscombinetoenablevisualprocessingw/cisofparamountimportanceinacademicperformance.
VisualProcessing
-beginsveryearly&developsthruinfancy,preschoolage&schoolingyears
-involvesvestibular&corticalcontrols&development
-Interferencew/devofanyoftheinterfacesresultsinthevisualprocessingbeingaffected.
StepsinInfantVisionDevelopment
•Atbirth,babiescan'tseeaswellasolderchildren/adults.Theireyes&visualsystemaren'tfullydeveloped.But
significantimprovementoccursduringthefirstfewmonthsoflife.
Atbirth
•Pooreyesight
•blinkinresponsetolightortouchingeye
•Eyesuncoordinated,maylookcross-eyed
•stareatobjectifheld8-10”away
•Initiallyfixeseyesonaface/lightthenbeginstofollowamovingobject
1Month
•followaslowlymovingblack&whitetargettomidline;hewillblinkatlightflash,hemayalsofollowfaces(eyes
&headbothmovingtogether).
•Acuityisstillpoor,&ocularmovementsmaybeuncoordinated.
•canonlyfocusabout8”to12”fromtheirface
•Looksatfaces&picturesw/contrastingblack&whiteimages
•Canfollowanobjectupto90deg
•Watchesparentclosely
•Tearsbegintoform
2Months
•eyesarenotwellcoordinated&mayappeartowanderorcrossed.Thisisusuallynormal.However,ifaneye
appearstoturninoroutconstantly,anevaluationiswarranted.
•Beginstoseeanobjectasoneimage
•Brieffixationoccurs,althoughocularmovementsarestilluncoordinated.attentiontoobjectsupto6″away.
•followsverticalmovementsbetterthanhorizontal,&isbeginningtobeawareofcolors(primarilyred&yellow)
3Months
•Ocularmovementsarecoordinatedmostofthetime;attractiontobothblac/white&coloredtargets.
•capableofglancingatsmallertargets(1inch),&isinterestedinfaces;visualattention&searchingbegins.
•beginstoassociatevisualstimuli&anevent(thebottleandfeeding).
•begintofollowmovingobjectswiththeireyes&reachforthings
4Months
•"Handregard"occur
•reacts(usuallysmiles)tofamiliarfaces.
•abletofollowavisualtargetpastmidline&cantrackhorizontally,vertically,&inacircle
•Canstareatablock
•Visualacuitymaybeinthe20/200to20/300range.
5Months
•abletolookatanobjectinhis/herownhands.
•visuallyawareoftheenvironment&canshiftgazefromneartofareasily
•can"study"objectsvisuallyatnearpoint&canconvergetheeyestodoso;canfixateobjectsat3”
•Eye-handcoordination(reaching)isusuallyachieved
•Depthperceptionisnotdevelopeduntilthefifthmonththattheeyesarecapableofworkingtogethertoforma
3Dviewoftheworldandbegintoseeindepth.
•Althoughaninfant'scolorvisionisnotassensitiveasanadult's,itisgenerallybelievedthatbabieshavegood
colorvisionbyfivemonthsofage.
6Months
•Eyemovementsarecoordinated&smooth;visioncanbeusedefficientlyatbothnearpoint&atdistance.
•Thechildrecognizesanddifferentiatesfacesat6”&canreachfor&graspavisualtarget.
•Handmovementsaremonitoredvisually
•interestedinwatchingfallingobjects,&fixatesonwheretheobjectdisappears.
6&9Months
•Acuityimprovesrapidly(tonearnormal).
•exploresvisually(watcheswhatisgoingonaroundhim/her).
•cantransferobjectsfromhandtohand,andinterestedingeometricpatterns.
9&12Months
•watchfaces&trytoimitateexpressions.
•Searchforhiddenobjects
•stareatsmallobjects
•Visuallyalerttonewpeople,objects&surroundings
•Differentiatebetweenfamiliar&unfamiliarpeople
•cannowjudgedistancesfairlywell&throwthingsw/precision.
1year
•Bothnearanddistantacuitiesaregood.
•Canwatchobjectsthataremovingfast
•Hecandiscriminatebetweensimplegeometricforms,scribblesw/crayon,&visuallyinterestedinpictures.
2years
•Myelinationofopticnerveiscompleted;allopticalskillsaresmooth&wellcoordinated.
•Visualacuityisnormal.
•canimitatemovements,matchsameobjectsbysingleproperties(color,shape),&canpointtospecificpictures
inabook.
3years
•Retinaltissueismature.
•candosimplepuzzles,
•candrawacrudecircle,&canput1"thingsintoholes

3. PreschoolVision:3to5YearsofAge
•fine-tuningthevisualabilitiesgainedduringinfancy&developingnewones.
•parentsneedtobealertforpresenceofvisionproblemslikecrossedeyesorlazyeye.
•parentsshouldwatchtheirchildforindicationofanydelaysindevelopment,w/cmaysignalvisionproblem.
Difficultywithrecognitionofcolors,shapes,lettersandnumberscanoccurifthereisavisionproblem.
School-agedVision:6to18y/o
•Visualacuity—abilitytoseeclearlyinthedistance,atintermediatedistance,&upclose
•EyeFocusing—abilitytoquickly&accuratelymaintainclearvisionasdistancefromobjectschange.allows
thechildtoeasilymaintainclearvisionovertimelikewhenreadingorwriting.
•Eyetracking—abilitytokeeptheeyesontargetwhenlookingfromoneobjecttoanother
•Eyeteaming—abilitytocoordinate&usebotheyestogetherwhenmovingtheeyes&abletojudgedistances
&seedepth
•Eye-handcoordination—abilitytousevisualinformationtomonitor&directthehands
•Visualperception—abilitytoorganizeimagesonaprintedpageintoletters,words&ideas&to
understand/rememberwhatisread.(photographicmemorydevelops)
VISUALMILESTONES(summary)
Afterbirth-Canfix&followalightsource,faceorlargecolourfultoy
1months-Fixationiscentral,steady&maintained,canfollowaslowtarget,&converge,preferlookingatface
3months-binovision&eyecoordination,eyesfollowamovinglight/face,responsivesmile.
6months-Reachesoutaccuratelyfortoys.
9months-lookforhiddentoys.
2years-Picturematching
3years-Lettermatchingofsingleletters(e.g.,SheridanGardiner)
5years-Snellenchartbymatchingornaming
NORMALVISUALDEVELOPMENT
•Pupillarylightreaction:30weeksgestation
•Blinkresponsetovisualstimuli:2-5mos
•Fixation-2mos
•Smoothpursuit:6-8weeks
•Saccades:1-3mos
•Optokineticnystagmus(OKN):2-4mos
•OcularAlignment:1mos
•Fovealmaturation:4mos
•Opticnervemyelination:7mosto2yrs
NORMALVISUALRESPONSE
Otherfunctionincorrelatewithvision
VISUALACUITYDEVELOPMENT INHUMAN
Develops&maturesfrombirthto6years
Newborn:quiteablurryvision:Indistinct&Shadowy
Improvessignificantlyoverthenext6months:Canrecognizethefaces
•Atbirth VA=6/240(20/800)
•1month VA=6/120(20/400)
•6months VA=6/30(20/200)
•1year VA=6/15(20/50)
PediatricsAgeGroup
Infants&Toddlers-birth-2y/o
Pre-schoolchildren-3-5y/o
Schoolagechildren-6-18y/o
VisualAcuity
-measureofthespatialresolutionofthevisualprocessingsystem
-Expressestheangularsizeofthedetailthatcanjustberesolvedbytheobserver
-Visualacuitytestingisaclinicalproceduretoaccesstheabilityofanindividualtodiscriminatedetailand
distinguishform.
4typesofVisualAcuity(D-RRL)
Detectionacuity:estimatestheminimumsizevisible.theactualpresence/absenceoftargetisdetermined
(Catforddrum,stycarballs)
Resolutionacuity:minimumseparationw/callowsdiscrimination.theminimumseparationdetectedbetween
theelementsofgratingsorcheckerboardisdetermined(preferentiallookingcharts,Leagratings)
Recognitionacuity:theminimumsize,w/cfacilitatesidentification(letters/picturesororientationof
symbolsareidentified(lettersorpictures)
Localizationacuity(VernierAcuity):estimatesabilitytodistinguishwhentwolinesplacedend-to-endis
displacedlaterally(differencesinspatialposition)ofatesttargetisdetermined
-Normaldevelopmentofvisualfunctionstartsw/thedetectionacuityacquiredatbirth,undergoesarapid
developmentintohigheracuityfunctionsuchasresolution,developinglateron.
-Therearemanytechniquesofvisualacuityassessmentavailabletoquantifythedifferentlevelofvisual
function

4. NormalvisualDevelopments
•Atbirth 6/120
•4months 6/60
•6months 6/36
•1year 6/18
•2years 6/6
VISUALACUITYOFINFANTEYES
VisionTestsinInfant