Refractive error

Refractive error means that the shape of your eye does not bend light correctly, resulting in a blurred image. The main types of refractive errors are myopia (nearsightedness), hyperopia (farsightedness), presbyopia (loss of near vision with age), and astigmatism.

1. By
Mr. Ravi Rai Dangi
Assistant Professor
MSc. Child Health Nursing

2. RefractiveError
Refractiveerrormeansthattheshapeofyoureyedoesnot
bendlightcorrectly,resultinginablurredimage.Themain
typesofrefractiveerrorsaremyopia(nearsightedness),
hyperopia(farsightedness),presbyopia(lossofnearvision
withage),andastigmatism.

3. RefractionMeans
Refractionisthebendingoflightasitpassesthrough
oneobjecttoanother.Visionoccurswhenlightraysare
bent(refracted)astheypassthroughthecorneaandthe
lens.Thelightisthenfocusedontheretina.
Theretinaconvertsthelight-raysintomessagesthat
aresentthroughtheopticnervetothebrain.Thebrain
interpretsthesemessagesintotheimageswesee.

4. Signs and Symptoms
Blurredvision
Doublevision
Haziness(uncleared)
Glareorhalosaroundbrightlights
Squinting
Headaches
Eyestrain

5. Risk factor / Etiology
Genetics
Marfansyndrome
X-linkeddisorders
Environmental
Readinghasalsobeenfoundtobeapredictorof
myopiainchildren.
Socioeconomicstatusandhigherlevelsofeducation
havealsobeenreportedtobeariskfactorfor
myopia.

6. Types

7. Myopia (nearsightedness)
Itisaconditionwhereobjectsupcloseappearclearly,
whileobjectsfarawayappearblurry.Fortreatmentuse
concavelens

8. Hyperopia (farsightedness)
Peoplewithhyperopiacanusuallyseedistantobjectswell,
buthavetroublefocusingonnearbyobjects.Fortreatment
useconvexlens

9. Astigmatism
Itisaconditioninwhichtheeyedoesnotfocuslight
evenlyontotheretina,thelight-sensitivetissueatthe
backoftheeye.
Thiscancauseimagestoappearblurryandstretchedout.
Cylindricalerroroccurswhentheincominglightraysare
unabletoreachacommonfocuswithintheeye.
Astigmatismdistortsorblursvisionforbothnearandfar
objects.

11. Presbyopia
Itisanage-relatedconditioninwhichtheabilitytofocus
upclosebecomesmoredifficult.
Astheeyeages,thelenscannolongerchangeshape
enoughtoallowtheeyetofocuscloseobjectsclearly.
Whentheflexibilityofthelensdeclines,typicallydueto
age.
Theindividualwouldexperiencedifficultyinnearvision,
oftenrelievedbyreadingglasses,bifocal,orprogressive
lenses

13. Diagnostic Evaluation
Dilating Eye Drops

14. Retinoscopy
Ahandheldinstrumentcalledaretinoscopeprojectsa
beamoflightintotheeye.Whenthelightismoved
verticallyandhorizontallyacrosstheeye,theexaminer
observesthemovementofthereflectedlightfromthe
backoftheeye.

15. Thisreflectioniscalledredreflex.Theexaminerthen
introduceslensesinfrontoftheeyeandasthepower
ofthelenseschanges,thereisacorrespondingchange
inthedirectionandpatternofthereflection.
Theexaminerkeepschangingthelensesuntilreaching
alenspowerthatindicatestherefractiveerrorofthe
patient.

16. Management
Refractiveerrorscanbecorrectedwitheyeglasses,
contactlenses,orsurgery
Eyeglassesarethesimplestandsafestwaytocorrect
refractiveerrors.

17. Inmanycases,contactlensesprovideclearervision,a
widerfieldofvision,andgreatercomfort.Theyareasafe
andeffectiveoptioniffittedandusedproperly.
Itisveryimportanttowashyourhandsandcleanyour
lensesasinstructedinordertoreducetheriskofinfection.
Contact Lens

18. RefractiveSurgery