Low vision introduction

Introduction to Low VisionIntroduction to Low Vision
Raju Kaiti, M. Optom
Consultant Optometrist
NEH

Bangkok Definition of LowBangkok Definition of Low
VisionVision
 ““A person with low vision is one who hasA person with low vision is one who has
impairment of visual functioning even afterimpairment of visual functioning even after
treatment and/or standard refractive correction, andtreatment and/or standard refractive correction, and
has a visual acuity of less than 6/18 to lighthas a visual acuity of less than 6/18 to light
perception, or a visual field less than 10 degreesperception, or a visual field less than 10 degrees
from the point of fixation, but who uses, or isfrom the point of fixation, but who uses, or is
potentially able to use, vision for the planning and/orpotentially able to use, vision for the planning and/or
execution of a task.execution of a task.””
 Management of low vision in children- Report of a WHOManagement of low vision in children- Report of a WHO
Consultation 1992Consultation 1992

Low vision categories – ICD-10Low vision categories – ICD-10
 World health OrganizationWorld health Organization’’s Tenth Revision of thes Tenth Revision of the
International statistical classification of diseases andInternational statistical classification of diseases and
related health problems( ICD-10) has included low visionrelated health problems( ICD-10) has included low vision
as category 1 and 2 of visual impairment.as category 1 and 2 of visual impairment.
 This classification defines low vision as corresponding toThis classification defines low vision as corresponding to
 Visual acuity of less than 6/18 but equal to or betterVisual acuity of less than 6/18 but equal to or better
than 3/60, orthan 3/60, or
 corresponding visual field loss, to less than 20corresponding visual field loss, to less than 20
degrees, in the better eye with best possibledegrees, in the better eye with best possible
correction.correction.

Low visionLow vision
 Low vision - the best corrected visual acuity inLow vision - the best corrected visual acuity in
the better eye less than 6/18 and/or visual fieldthe better eye less than 6/18 and/or visual field
less than 20 degree from the point of fixation.less than 20 degree from the point of fixation.
 Blindness – the best corrected visual acuity inBlindness – the best corrected visual acuity in
the better eye less than 3/60 and/or visual fieldthe better eye less than 3/60 and/or visual field
less than 10 from the point of fixation.less than 10 from the point of fixation.

Aspects of vision lossAspects of vision loss
 DisorderDisorder
 Anatomic changes- inflammation, atrophy, scarAnatomic changes- inflammation, atrophy, scar
 ImpairmentImpairment
 Functional changes- visual acuity, VF, contrastFunctional changes- visual acuity, VF, contrast
sensitivitysensitivity
 DisabilityDisability
 Skills and abilities affected- reading, writing, DLS,Skills and abilities affected- reading, writing, DLS,
MobilityMobility
 HandicapHandicap
 Socioeconomic consequences- extra effort, loss ofSocioeconomic consequences- extra effort, loss of
independenceindependence

Goals of Low Vision ManagementGoals of Low Vision Management
 Increase functionalityIncrease functionality
 Make the most of the remaining visionMake the most of the remaining vision
 Provide link to community resources andProvide link to community resources and
support servicessupport services
 EducationEducation

Functional Effects of LowFunctional Effects of Low
VisionVision
 Loss of central vision (visualLoss of central vision (visual
acuity)acuity)
 Loss of peripheral vision (visualLoss of peripheral vision (visual
field)field)
 Glare and contrastGlare and contrast

Issues Related to Decreased AcuityIssues Related to Decreased Acuity
 Difficulty readingDifficulty reading
 Problems writing/ completingProblems writing/ completing
paperworkpaperwork
 Inability to recognize distanceInability to recognize distance
objects and facesobjects and faces

Issues Related to Visual Field LossIssues Related to Visual Field Loss
 Location of scotoma important!Location of scotoma important!
 Generalized loss of visual field difficultGeneralized loss of visual field difficult
to compensate forto compensate for
 Mobility and independent travelMobility and independent travel
 Reading may require adaptationsReading may require adaptations

Issues Related to ContrastIssues Related to Contrast
 Need for additional lightingNeed for additional lighting
 Problems with glareProblems with glare
 Increased adjustment to changes inIncreased adjustment to changes in
illuminationillumination
 Visual discomfort and fatigueVisual discomfort and fatigue

Common ConditionsCommon Conditions
 Macular DegenerationMacular Degeneration
 GlaucomaGlaucoma
 Diabetic RetinopathyDiabetic Retinopathy
 Stroke/ brain injuryStroke/ brain injury
 Retinitis pigmentosaRetinitis pigmentosa
 Optic Nerve diseaseOptic Nerve disease
 AlbinismAlbinism
 NystagmusNystagmus
 Cortical Visual ImpairmentCortical Visual Impairment
 CataractCataract
 Corneal OpacitiesCorneal Opacities
 ToxoplasmosisToxoplasmosis
 AmblyopiaAmblyopia
 Retinal DetachmentRetinal Detachment
 Refractive errorRefractive error

Current blindness and low visionCurrent blindness and low vision
datadata
 Estimated Visually impaired person globally – 253Estimated Visually impaired person globally – 253
millionmillion
 36 million36 million
 217 million – low vision (moderate to severe visual217 million – low vision (moderate to severe visual
impairment)impairment)
 81% of people who are blind or have moderate or severe81% of people who are blind or have moderate or severe
VI are aged 50 years and above.VI are aged 50 years and above.
 Over 80% of all vision impairment can be prevented orOver 80% of all vision impairment can be prevented or
cured.cured.
 Un-operated cataract remains the leading cause ofUn-operated cataract remains the leading cause of
blindness in low and middle income countries.blindness in low and middle income countries.

Causes of Low VisionCauses of Low Vision
 Major causes of moderate to severe visualMajor causes of moderate to severe visual
impairment:impairment:
 Uncorrected refractive errors, 53%Uncorrected refractive errors, 53%
 Un-operated cataract, 25%Un-operated cataract, 25%
 ARMD, 4%ARMD, 4%
 Glaucoma, 2%Glaucoma, 2%
 Diabetic retinopathy, 1%Diabetic retinopathy, 1%

 Major causes of blindness:Major causes of blindness:
 Un-operated cataract, 35%Un-operated cataract, 35%
 Uncorrected refractive errors, 21%Uncorrected refractive errors, 21%
 Glaucoma, 8%Glaucoma, 8%
 An estimated 19 million children are visionAn estimated 19 million children are vision
impaired.impaired.
 Of these, 12 million children have a visionOf these, 12 million children have a vision
impairment due to refractive error.impairment due to refractive error.
 About 1.4 million have irreversible blindnessAbout 1.4 million have irreversible blindness

Risk FactorsRisk Factors
 Etiologies may be: Etiologies may be:
 CongenitalCongenital: Pre- or postnatal trauma,: Pre- or postnatal trauma,
genetic or developmental abnormalitiesgenetic or developmental abnormalities

 HereditaryHereditary: Ocular diseases (e.g.,: Ocular diseases (e.g.,
retinitis pigmentosa, Stargardt's macularretinitis pigmentosa, Stargardt's macular
degeneration)degeneration)
 AcquiredAcquired: Ocular infection or disease,: Ocular infection or disease,
neurological insult, trauma, age-relatedneurological insult, trauma, age-related
changes or systemic disease.changes or systemic disease.

CataractCataract
 Clouding of the lensClouding of the lens
 Difficulty recognizing facesDifficulty recognizing faces
 Total Blindness in mature stateTotal Blindness in mature state
 Causes: Aging, UV exposure, TraumaCauses: Aging, UV exposure, Trauma
 Treatment: SurgeryTreatment: Surgery
 19 million people worldwide are blind due to19 million people worldwide are blind due to
cataractscataracts
 Comprises 40% of blindness in AsiaComprises 40% of blindness in Asia

GlaucomaGlaucoma
 Increased IOP damages the optic nerveIncreased IOP damages the optic nerve
causing partial or total blindnesscausing partial or total blindness
 Patient is asymptomatic initiallyPatient is asymptomatic initially
 First sign is side vision lossFirst sign is side vision loss
 Treatment: Early diagnosis and treatmentTreatment: Early diagnosis and treatment
with medicine or surgerywith medicine or surgery

Macular DegenerationMacular Degeneration
 Damage to maculaDamage to macula
 Central vision deterioratesCentral vision deteriorates
 Patient will never be completely blind becausePatient will never be completely blind because
their peripheral vision will always remaintheir peripheral vision will always remain
 Complaints: Difficult to read, recognize faces,Complaints: Difficult to read, recognize faces,
distorted imagesdistorted images
 Causes: Aging (leading cause of low vision,Causes: Aging (leading cause of low vision,
increased life expectancy)increased life expectancy)

Diabetic RetinopathyDiabetic Retinopathy
 Affects small blood vessels of eyes causingAffects small blood vessels of eyes causing
leakageleakage
 Not enough blood and nutrients reach the retinaNot enough blood and nutrients reach the retina
 New blood vessels develop (neovascularization)New blood vessels develop (neovascularization)
 Causes visual field loss, retinal detachments,Causes visual field loss, retinal detachments,
loss and fluctuation of visionloss and fluctuation of vision
 Treatment: Medical (diabetic control), Laser toTreatment: Medical (diabetic control), Laser to
stop further damagestop further damage

Retinal DetachmentRetinal Detachment
 Elevation of retina from underlyingElevation of retina from underlying
supportive tissue, causing damage to thesupportive tissue, causing damage to the
retinaretina
 Depending upon the location, duration,Depending upon the location, duration,
severity of detached retina, vision loss canseverity of detached retina, vision loss can
range from severe to mildrange from severe to mild
 Treatment: surgicalTreatment: surgical

Retinitis PigmentosaRetinitis Pigmentosa
 Disease that affects the pigment of theDisease that affects the pigment of the
retinaretina
 Degeneration in periphery at first, thenDegeneration in periphery at first, then
progresses centrally with timeprogresses centrally with time
 Causes field constriction and nightCauses field constriction and night
blindnessblindness

TraumaTrauma
 Traumatic insult to the eyeTraumatic insult to the eye
 Vision loss depending on severity, natureVision loss depending on severity, nature
and extent of damage that occurred to theand extent of damage that occurred to the
eyeeye

Optic AtrophyOptic Atrophy
 Loss of optic nerve functionLoss of optic nerve function
 Usually progressive and will often lead toUsually progressive and will often lead to
total blindnesstotal blindness
 Patients will have central vision loss asPatients will have central vision loss as
well as visual field losswell as visual field loss

AmblyopiaAmblyopia
 Lazy eye causing low vision due to lack ofLazy eye causing low vision due to lack of
proper development of eyes and visualproper development of eyes and visual
system during childhoodsystem during childhood
 Vision loss may be mild to severeVision loss may be mild to severe
 Treatment: possible if child is brought toTreatment: possible if child is brought to
hospital before 10 years of agehospital before 10 years of age

ToxoplasmosisToxoplasmosis
 Organism: Toxoplasma gondiiOrganism: Toxoplasma gondii
 Enters retina via blood and damages partEnters retina via blood and damages part
of the retina permanently causing severeof the retina permanently causing severe
vision lossvision loss
 Severely decreased vision if macula isSeverely decreased vision if macula is
involvedinvolved

Stroke/Brain lesionStroke/Brain lesion
 Disease of the brain also causes visualDisease of the brain also causes visual
damagedamage
 Patients may suffer from double vision,Patients may suffer from double vision,
hemianopic field defect, problem with eyehemianopic field defect, problem with eye
movement, may cause optic nerve deathmovement, may cause optic nerve death
leading to total blindnessleading to total blindness

Corneal OpacitiesCorneal Opacities
 Injury to the cornea heals with opaqueInjury to the cornea heals with opaque
white opacitieswhite opacities
 Vision loss depends upon the location andVision loss depends upon the location and
extent of opacity ranging from mild toextent of opacity ranging from mild to
severesevere
 Treatment: Corneal TransplantTreatment: Corneal Transplant

Central Field Loss DisordersCentral Field Loss Disorders
 Optic AtrophyOptic Atrophy

Multiple Field LossMultiple Field Loss
 Retinal detachmentRetinal detachment
 TraumaTrauma

Tunnel VisionTunnel Vision
 Retinitis PigmentosaRetinitis Pigmentosa
 StrokeStroke

Contrast Loss and GlareContrast Loss and Glare
ProblemsProblems
 CataractsCataracts
 Corneal DiseaseCorneal Disease
 AlbinismAlbinism

Blurred VisionBlurred Vision
 CataractsCataracts
 Corneal DiseaseCorneal Disease

DistortionDistortion
 Retinal DetachmentRetinal Detachment

Leading Causes of LegalLeading Causes of Legal
BlindnessBlindness
 Birth to 19 years of ageBirth to 19 years of age
 Congenital Cataract, Optic Atrophy, Albinism, ROP,Congenital Cataract, Optic Atrophy, Albinism, ROP,
Cone-rod dystrophyCone-rod dystrophy
 20-44 years of age20-44 years of age
 Albinism, Cone-rod Dystrophy, Optic Atrophy, Myopia,Albinism, Cone-rod Dystrophy, Optic Atrophy, Myopia,
Retintis Pigmentosa, Diabetic Retinopathy, MacularRetintis Pigmentosa, Diabetic Retinopathy, Macular
DegenerationDegeneration
 Diabetic Retinopathy, Glaucoma, RetinitisDiabetic Retinopathy, Glaucoma, Retinitis
Pigmentosa, Macular Degeneration, CataractsPigmentosa, Macular Degeneration, Cataracts

Leading Causes of LegalLeading Causes of Legal
BlindnessBlindness
 Macular degeneration, Diabetic retinopathy,Macular degeneration, Diabetic retinopathy,
Glaucoma, Cataracts, Retinitis PigmentosaGlaucoma, Cataracts, Retinitis Pigmentosa
 75 years of age and older75 years of age and older
 ARMD, Glaucoma, Cataract, DiabeticARMD, Glaucoma, Cataract, Diabetic
retinopathyretinopathy
 Source: The Feinbloom Vision Rehabilitation Center of The Eye Institute atSource: The Feinbloom Vision Rehabilitation Center of The Eye Institute at
the Pennsylvania College of Optometrythe Pennsylvania College of Optometry

Factors Affecting PrognosisFactors Affecting Prognosis
 Visual AcuityVisual Acuity
 DurationDuration
 Visual FieldsVisual Fields
 Stability of ConditionStability of Condition
 AgeAge
 MotivationMotivation
 EducationEducation
 Emotional StateEmotional State
 PersonalityPersonality

Incidence and NeedIncidence and Need
 Incidence of visually impairing conditionsIncidence of visually impairing conditions
increases with age.increases with age.
 The number of persons with severe visualThe number of persons with severe visual
impairments is expected to rise as medicalimpairments is expected to rise as medical
advances increase the survival of infants andadvances increase the survival of infants and
adults.adults.
 There will be a greater need for rehabilitation asThere will be a greater need for rehabilitation as
survival increases for patients with traumaticsurvival increases for patients with traumatic
brain injuries.brain injuries.

Exam SequenceExam Sequence
 History/ intakeHistory/ intake
 Visual acuityVisual acuity
 Visual field testingVisual field testing
 PupilsPupils
 Extraocular muscle testingExtraocular muscle testing
 RefractionRefraction
 Color vision and Contrast TestingColor vision and Contrast Testing
 Ocular HealthOcular Health

Comprehensive Exam ofComprehensive Exam of
Patient with Low VisionPatient with Low Vision
 Patient HistoryPatient History
 Visual AcuityVisual Acuity
 RefractionRefraction
 Ocular Motility and Binocular Vision AssessmentOcular Motility and Binocular Vision Assessment
 Visual Field AssessmentVisual Field Assessment
 Ocular Health AssessmentOcular Health Assessment
 Supplemental TestingSupplemental Testing

History takingHistory taking
inin
Low VisionLow Vision

How to start?How to start?
 Observation & InformationObservation & Information
 Presenting historyPresenting history
 General health historyGeneral health history
 Social historySocial history
 Functional historyFunctional history
 Psychological historyPsychological history

 Observe how the patient enters the roomObserve how the patient enters the room
 Observe the clothing & personalityObserve the clothing & personality
 Observe his behavior & communicationObserve his behavior & communication
skillsskills
ObservationObservation

General informationGeneral information
 Name, Age/Gender, Accompanied byName, Age/Gender, Accompanied by
 Causes of low vision, referred byCauses of low vision, referred by
 Financial statusFinancial status
 Academic/ EmploymentAcademic/ Employment

 Unilateral/bilateral decrease in visionUnilateral/bilateral decrease in vision
 Major problemsMajor problems
Presenting historyPresenting history

 If any/similar problem in family?If any/similar problem in family?
 Consanguineous marriage?Consanguineous marriage?
 Systemic illness- diabetes, glaucomaSystemic illness- diabetes, glaucoma
 Genetic disorders- albinismGenetic disorders- albinism
Family historyFamily history

Visual historyVisual history
 Gradual/sudden vision lossGradual/sudden vision loss
 StableStable
 Any surgery – cataract?Any surgery – cataract?
 Glaucoma- medicine?Glaucoma- medicine?
 Macular diseases- laser?Macular diseases- laser?
 Significant problems- night blindness,Significant problems- night blindness,
glare, Color vision, field loss, stereopsis,glare, Color vision, field loss, stereopsis,
Adaptation?Adaptation?

General health historyGeneral health history
 Birth history? Delayed milestone?Birth history? Delayed milestone?
Mental retardation?Mental retardation?
 Hearing loss- hearing aids?Hearing loss- hearing aids?
 Arthritis – affecting hands?Arthritis – affecting hands?
 Stroke- affecting side?Stroke- affecting side?
 Diabetes- insulin dependent?Diabetes- insulin dependent?
 Heart diseases, cancer, HTN,Heart diseases, cancer, HTN,
Accidents etc.Accidents etc.
 Medicine undergone, undergoing?Medicine undergone, undergoing?

 Marital StatusMarital Status
 Living arrangementLiving arrangement
 Family/dependentsFamily/dependents
 Employment/ Retired?Employment/ Retired?
Social historySocial history

Psychological historyPsychological history
 Self analysis of own performance levelSelf analysis of own performance level
 Staying all the time at homeStaying all the time at home
 FrustrationFrustration
 ConfidenceConfidence
 Sharing & social gatheringSharing & social gathering
 Communication – hesitationCommunication – hesitation
 Needs lot of assistance?Needs lot of assistance?

Functional historyFunctional history
 Glasses- how long? Still working?Glasses- how long? Still working?
 Low vision care- LVD used- source ofLow vision care- LVD used- source of
LVD- LVD in current useLVD- LVD in current use
 Near vision task problem?Near vision task problem?
 Newspaper print, school/college books/Newspaper print, school/college books/
other reading materials,other reading materials,
 specific task- insulin via syringe, tailor-specific task- insulin via syringe, tailor-
needling, officer- typing/readingneedling, officer- typing/reading
 What to ask- working environment, lighting,What to ask- working environment, lighting,
contrast, print size etccontrast, print size etc

 Writing task problem?Writing task problem?
 Write in straight lineWrite in straight line
 Sign documentsSign documents
 Type of writing pen used?Type of writing pen used?
 Distance vision task problemsDistance vision task problems
 Chalkboard – sitting distance/environmentChalkboard – sitting distance/environment
 Recognizing faces- reaction in facesRecognizing faces- reaction in faces
 Street name/ bus numberStreet name/ bus number
 Watching TVWatching TV
 Sports/ outdoor activitiesSports/ outdoor activities

 Specific lighting needSpecific lighting need
 Reduced light/ bright lightReduced light/ bright light
 Fluorescent/incandescent light – at home & workingFluorescent/incandescent light – at home & working
environmentenvironment
 MobilityMobility
 Outdoor/indoorOutdoor/indoor
 Day/ nightDay/ night
 Familiar/unfamiliar placesFamiliar/unfamiliar places
 Bumping into objectsBumping into objects
 Going down steps/ curbsGoing down steps/ curbs
 Driving/ cycling problem- what conditions?Driving/ cycling problem- what conditions?

 Glare problemGlare problem
 Delayed adaptationDelayed adaptation
 Color perceptionColor perception
 Daily living skillsDaily living skills
 Home managementHome management
 Self help skillsSelf help skills
 Money/food identificationMoney/food identification
 Summarize the problem- state the patientsSummarize the problem- state the patients
goal - try to solve them.goal - try to solve them.

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