Visual impairment 2

Visual ImpairmentVisual Impairment
Medical and PsychosocialMedical and Psychosocial
Aspects of DisabilityAspects of Disability

IntroductionIntroduction
• Vision impairment affects a significantVision impairment affects a significant
proportion of middle-aged and older Americansproportion of middle-aged and older Americans
– 1 in 6 adults (17%), age 45 and older, representing1 in 6 adults (17%), age 45 and older, representing
13.5 million Americans, reports some form of vision13.5 million Americans, reports some form of vision
impairment even when wearing glasses or contactimpairment even when wearing glasses or contact
lenseslenses
• The prevalence of visual impairments increaseThe prevalence of visual impairments increase
with agewith age
– 15% of people 45-6415% of people 45-64
– 17% of people 65-7417% of people 65-74
– 26% of people 75 and older26% of people 75 and older

Factors Affecting Visual FunctionFactors Affecting Visual Function
and Their Treatmentand Their Treatment
• Visual Acuity - ability to see "detail"Visual Acuity - ability to see "detail"
– Measured using testing distance/letter sizeMeasured using testing distance/letter size
– Normal is 20/20Normal is 20/20
– Limitation on acuity level is generally determined by the spacingLimitation on acuity level is generally determined by the spacing
of the conesof the cones
– Treatment: glasses or some form of magnificationTreatment: glasses or some form of magnification
• Visual Field - a person's peripheral visionVisual Field - a person's peripheral vision
– Scotoma - loss of vision in an areaScotoma - loss of vision in an area
• ContrastContrast
• Lighting and GlareLighting and Glare
– Often, too much light can be as detrimental as not enoughOften, too much light can be as detrimental as not enough

Definition of Legal BlindnessDefinition of Legal Blindness
• WHO Definition:WHO Definition: Best-corrected visual acuityBest-corrected visual acuity
of less than 6/120 (<20/400) in the better-seeingof less than 6/120 (<20/400) in the better-seeing
eye.eye.
• US Definition:US Definition: Best-corrected visual acuity ofBest-corrected visual acuity of
6/60 or worse (6/60 or worse (<<20/200) in the better-seeing20/200) in the better-seeing
eye.eye.
OROR
• Peripheral visual field is restricted to 20° or lessPeripheral visual field is restricted to 20° or less
in the widest meridian of the better eyein the widest meridian of the better eye
• (US Definition of Low Vision:(US Definition of Low Vision: best-corrected visual acuity of 6/12 (<20/40)best-corrected visual acuity of 6/12 (<20/40)
in better-seeing eye.)in better-seeing eye.)

StatisticsStatistics
• In 2000 there were 937,000 blindIn 2000 there were 937,000 blind
Americans older than 40 (0.78%)Americans older than 40 (0.78%)
• 2,400,000 with low vision (1.98%)2,400,000 with low vision (1.98%)
• Thus, there were 3.3 million AmericansThus, there were 3.3 million Americans
aged 40 or more with a visual impairmentaged 40 or more with a visual impairment
in 2000in 2000
The Eye Diseases Prevalence Research Group (2004). Causes and prevalence of visualThe Eye Diseases Prevalence Research Group (2004). Causes and prevalence of visual
impairment among adults in the United States.impairment among adults in the United States. Archives of Ophthalmology, 122Archives of Ophthalmology, 122, 477-485., 477-485.

The Eye Diseases Prevalence Research Group, Arch Ophthalmol 2004;122:477-485.
AMD=age-related macular degeneration, DR=diabetic retinopathy
Causes of blindness (best-corrected visual acuity <6/60 [<20/200] in the better-
seeing eye) by race/ethnicity

.
The Eye Diseases Prevalence Research Group, Arch Ophthalmol 2004;122:477-485.
AMD=age-related macular degeneration, DR=diabetic retinopathy
Causes of low vision (best-corrected visual acuity <6/12 [<20/40] in the better-seeing
eye, excluding those who were categorized as being blind by the US definition) by
race/ethnicity

Prevalence of Blindness by AgePrevalence of Blindness by Age
and Race (US)and Race (US)
WhiteWhite BlackBlack HispanicHispanic
40-4940-49 0.120.12 0.180.18 0.050.05
50-5450-54 0.100.10 0.340.34 0.100.10
55-5955-59 0.110.11 0.520.52 0.160.16
60-6460-64 0.150.15 0.810.81 0.260.26
65-6965-69 0.230.23 1.251.25 0.410.41
70-7470-74 0.430.43 1.931.93 0.640.64
75-7975-79 0.930.93 2.962.96 0.990.99
>>8080 6.826.82 6.856.85 2.422.42

CataractsCataracts
• A cataract is opacity or clouding ofA cataract is opacity or clouding of
the lens that may develop as athe lens that may develop as a
result of aging, trauma, hereditaryresult of aging, trauma, hereditary
factors, birth defects, or diabetesfactors, birth defects, or diabetes
• Cataracts are a normal part of agingCataracts are a normal part of aging
– Approximately 50% of AmericansApproximately 50% of Americans
between 65 and 74 and 70% overbetween 65 and 74 and 70% over
age 75 have cataractsage 75 have cataracts
• Prevalence factorsPrevalence factors
– Caucasians are three times as likelyCaucasians are three times as likely
as African-Americans to developas African-Americans to develop
cataractscataracts
– Smokers have a 60% increaseSmokers have a 60% increase
– Those taking medication for gout areThose taking medication for gout are
twice as likely to develop cataractstwice as likely to develop cataracts
• The greater the progression of theThe greater the progression of the
cataract, the greater the visualcataract, the greater the visual
impairment from the effects of glare,impairment from the effects of glare,
loss of contrast, and decreasedloss of contrast, and decreased
visual acuityvisual acuity
• Normally, cataracts are successfullyNormally, cataracts are successfully
treated with surgerytreated with surgery
• Assuming no complications, thereAssuming no complications, there
should be no vocational implicationsshould be no vocational implications
following cataract surgeryfollowing cataract surgery
No cataract cataract

Corneal DiseaseCorneal Disease
• The cornea is a structure that is prone to dystrophies, deposition,The cornea is a structure that is prone to dystrophies, deposition,
noninflammatory progressive thinning (keratoconus), infection, viralnoninflammatory progressive thinning (keratoconus), infection, viral
diseases, and traumadiseases, and trauma
• Interference with corneal integrity can result in a blurred or distorted imageInterference with corneal integrity can result in a blurred or distorted image
on the retinaon the retina
– May experience severe glare, cloudy vision, and reduced acuityMay experience severe glare, cloudy vision, and reduced acuity
• TreatmentTreatment
– Keratoplasty is the primary method of restoring vision for an individual with aKeratoplasty is the primary method of restoring vision for an individual with a
diseased, irregular, or scarred cornea - procedure involves transplanting adiseased, irregular, or scarred cornea - procedure involves transplanting a
healthy cornea from a compatible donorhealthy cornea from a compatible donor
– Recently, lasers have been used to treat some corneal problemsRecently, lasers have been used to treat some corneal problems
• Vocational ImplicationsVocational Implications
– Vocational goals will be dependent on the degree to which the retinal image isVocational goals will be dependent on the degree to which the retinal image is
compromisedcompromised

Macular DegenerationMacular Degeneration
• Macular degeneration is caused byMacular degeneration is caused by
degenerative changes to the macular areadegenerative changes to the macular area
of the retina that result in atrophy,of the retina that result in atrophy,
hemorrhage, exudates, fibrovascular scars,hemorrhage, exudates, fibrovascular scars,
or cyst formationsor cyst formations
• Risk factorsRisk factors
– CaucasianCaucasian
– Family historyFamily history
– High blood pressure or a history ofHigh blood pressure or a history of
hypertensionhypertension
– Light iris colorLight iris color
– SmokingSmoking
• Functional PresentationFunctional Presentation
– Visually manifested as distortions, a decreaseVisually manifested as distortions, a decrease
in the visual acuity, a decrease in colorin the visual acuity, a decrease in color
recognition, a loss of contrast, or an absoluterecognition, a loss of contrast, or an absolute
or relative area of no vision (scotoma)or relative area of no vision (scotoma)
– Reading may become increasingly difficultReading may become increasingly difficult
and driving may have to be discontinuedand driving may have to be discontinued

Macular DegenerationMacular Degeneration
– Laser treatment can sometimes be used to slow the progression ofLaser treatment can sometimes be used to slow the progression of
the diseasethe disease
– Other treatments that have been investigated (but not yetOther treatments that have been investigated (but not yet
established) include the use of radiation, laser treatment of drusenestablished) include the use of radiation, laser treatment of drusen
(small globular pathological growths formed on optic papilla or on(small globular pathological growths formed on optic papilla or on
Descemet's membrane), photodynamic therapy, submacularDescemet's membrane), photodynamic therapy, submacular
surgery, retinal cell transplantation, and the use of vascularsurgery, retinal cell transplantation, and the use of vascular
endothelial growth factorendothelial growth factor
– DrivingDriving
– Vision rehabilitation program may be needed before being able toVision rehabilitation program may be needed before being able to
return to workreturn to work
• Accommodations/Assistive TechnologyAccommodations/Assistive Technology
– Lenses and magnification devicesLenses and magnification devices
– Talking booksTalking books
– Bold, felt-tip pensBold, felt-tip pens
– Talking clocks (and other talking devices and appliances)Talking clocks (and other talking devices and appliances)

Diabetic RetinopathyDiabetic Retinopathy
• Diabetes accounts for about 5,000Diabetes accounts for about 5,000
new cases of blindness each year andnew cases of blindness each year and
people with diabetes have a 25 timespeople with diabetes have a 25 times
greater risk for blindness than thegreater risk for blindness than the
general populationgeneral population
– Approximately 40% of people withApproximately 40% of people with
diabetes have diabetic retinopathydiabetes have diabetic retinopathy
– Fluctuating or severely decreasedFluctuating or severely decreased
visual acuityvisual acuity
– Problems due to glare, reducedProblems due to glare, reduced
contrast sensitivity, and various typescontrast sensitivity, and various types
of visual field problemsof visual field problems
– May have transient episodes ofMay have transient episodes of
diplopiadiplopia

Diabetic RetinopathyDiabetic Retinopathy
– Rehabilitation considerations must include notRehabilitation considerations must include not
only vision but also the effect of diabetes ononly vision but also the effect of diabetes on
other systemsother systems
– Low-vision devicesLow-vision devices
– Prisms to correct transitory diplopiaPrisms to correct transitory diplopia

GlaucomaGlaucoma
• If left untreated, results in the destruction of theIf left untreated, results in the destruction of the
peripheral retinaperipheral retina
• Basically three types of glaucomaBasically three types of glaucoma
– Chronic open-angle glaucoma: elevated pressureChronic open-angle glaucoma: elevated pressure
over time eventually affects the optic nerve and visualover time eventually affects the optic nerve and visual
fieldfield
– Acute (closed-angle) glaucoma: rapid increase orAcute (closed-angle) glaucoma: rapid increase or
spiking of the intraocular pressure that may bespiking of the intraocular pressure that may be
accompanied by intense pain and even nausea oraccompanied by intense pain and even nausea or
vomitingvomiting
– Low-tension glaucoma: may be caused by aLow-tension glaucoma: may be caused by a
decrease in blood flow to the optic nervedecrease in blood flow to the optic nerve
• Over a period of time, especially if leftOver a period of time, especially if left
untreated, irreversible optic nerve and visualuntreated, irreversible optic nerve and visual
field damage will occur, impairing night vision,field damage will occur, impairing night vision,
visual acuity, mobility, and reading skillsvisual acuity, mobility, and reading skills

GlaucomaGlaucoma
– Medications that decrease production of aqueous humor or facilitateMedications that decrease production of aqueous humor or facilitate
outflow of fluidoutflow of fluid
– Laser surgery to create drainage holesLaser surgery to create drainage holes
– Other surgery procedures to assist with drainageOther surgery procedures to assist with drainage
– Progressive loss of vision may result in difficulty in performing one's jobProgressive loss of vision may result in difficulty in performing one's job
– Low-vision devices, including spectacles, hand and stand magnifiers,Low-vision devices, including spectacles, hand and stand magnifiers,
closed circuit TV, and lightingclosed circuit TV, and lighting
– Absorptive lenses enhance the apparent brightness of the scene andAbsorptive lenses enhance the apparent brightness of the scene and
often aid in mobilityoften aid in mobility
– Modifications in the work space may be required, with high technology,Modifications in the work space may be required, with high technology,
including voice-output devicesincluding voice-output devices

AlbinismAlbinism
• Albinism is a trait that is inherited through autosomal recessive orAlbinism is a trait that is inherited through autosomal recessive or
sex-linked transmission and results in characteristics that affect thesex-linked transmission and results in characteristics that affect the
pigmentation of the skin and hair as well as the iris and retinapigmentation of the skin and hair as well as the iris and retina
• Persons with albinism have a decrease in visual acuity due toPersons with albinism have a decrease in visual acuity due to
macular aplasiamacular aplasia
• Treatment consists of corrective spectacle lenses as well asTreatment consists of corrective spectacle lenses as well as
absorptive lenses to reduce light sensitivityabsorptive lenses to reduce light sensitivity
– Similar to other types of visual impairmentsSimilar to other types of visual impairments
– Need to pay attention to exposure to sunlightNeed to pay attention to exposure to sunlight
– Low-vision devices, including strong microscopic reading lenses,Low-vision devices, including strong microscopic reading lenses,
magnifiers, absorptive lenses, and telescopic lensesmagnifiers, absorptive lenses, and telescopic lenses

Retinitis PigmentosaRetinitis Pigmentosa
• A progressive eye disease that affectsA progressive eye disease that affects
the pigmentary layer of the retina, andthe pigmentary layer of the retina, and
most commonly affects the peripherymost commonly affects the periphery
or midperiphery of the retinaor midperiphery of the retina
• Most common cause of inheritedMost common cause of inherited
blindnessblindness
• In addition, 30% of people with RPIn addition, 30% of people with RP
report some degree of hearing lossreport some degree of hearing loss
– Night vision and peripheral vision goNight vision and peripheral vision go
hand in hand - the more advanced thehand in hand - the more advanced the
RP, the greater loss of peripheralRP, the greater loss of peripheral
vision and the more difficult to travelvision and the more difficult to travel
– Reading becomes more and moreReading becomes more and more
difficult as the visual field becomesdifficult as the visual field becomes
smallsmall
– Glare or light sensitivity is frequentlyGlare or light sensitivity is frequently
associated with RPassociated with RP

Retinitis PigmentosaRetinitis Pigmentosa
– At present, no medical or surgical treatments are known to stop orAt present, no medical or surgical treatments are known to stop or
decrease the progression of RPdecrease the progression of RP
– Refractive corrections are necessary, along with absorptive lensesRefractive corrections are necessary, along with absorptive lenses
to cut down the glare or light sensitivityto cut down the glare or light sensitivity
– Contrast-enhancing lenses may be beneficial in enhancingContrast-enhancing lenses may be beneficial in enhancing
performance and reducing adaptation times between outdoors andperformance and reducing adaptation times between outdoors and
indoorsindoors
– Individuals with severe progressive visual field loss should notIndividuals with severe progressive visual field loss should not
contemplate occupations that will necessitate drivingcontemplate occupations that will necessitate driving
– Closed-circuit TV to enable the person to control the brightness andClosed-circuit TV to enable the person to control the brightness and
contrast of the image viewedcontrast of the image viewed
– Prism lenses to increase the awareness of the peripheryPrism lenses to increase the awareness of the periphery
– The Nightsope might be able to be used for mobility under dimThe Nightsope might be able to be used for mobility under dim
illuminationillumination
– Mobility devices, such as a traveling cane, special laser cane,Mobility devices, such as a traveling cane, special laser cane,
sensory device, or Seeing Eye dogsensory device, or Seeing Eye dog

Peripheral Visual Field LossPeripheral Visual Field Loss
from Strokes or Tumorsfrom Strokes or Tumors• A person who has a stroke or tumor can be left with aA person who has a stroke or tumor can be left with a
resultant visual field lossresultant visual field loss
• In addition, can affect perception of visual form, color,In addition, can affect perception of visual form, color,
object meaning, recognition, and attentionobject meaning, recognition, and attention
• May also be disorders of the visual system such asMay also be disorders of the visual system such as
hallucinationshallucinations
• Vocational Implications - drivingVocational Implications - driving
– Prisms to enhance spatial awarenessPrisms to enhance spatial awareness
– Mirrors to facilitate peripheral field awarenessMirrors to facilitate peripheral field awareness
– Low-vision devicesLow-vision devices

General Vocational ImplicationsGeneral Vocational Implications
• Transportation issues need to beTransportation issues need to be
consideredconsidered
• Safety issues need to be consideredSafety issues need to be considered

ResourcesResources
• The National Society to Prevent Blindness (www.eyeinfo.org/national.html)The National Society to Prevent Blindness (www.eyeinfo.org/national.html)
• Prevent Blindness America (http://www.preventblindness.org/)Prevent Blindness America (http://www.preventblindness.org/)
• Prevent Blindness Florida (www.preventblindness.org/florida/)Prevent Blindness Florida (www.preventblindness.org/florida/)
• American Academy of Opthamology (http://www.aao.org/)American Academy of Opthamology (http://www.aao.org/)
• Glaucoma Research Foundation (http://www.glaucoma.org/)Glaucoma Research Foundation (http://www.glaucoma.org/)
• Lighthouse International (http://www.lighthouse.org/)Lighthouse International (http://www.lighthouse.org/)
• AMD Alliance International (http://www.amdalliance.org/)AMD Alliance International (http://www.amdalliance.org/)
• National Eye Institute (http://www.nei.nih.gov/)National Eye Institute (http://www.nei.nih.gov/)
• National RP Foundation (www.rpsa.org.za/training.htm)National RP Foundation (www.rpsa.org.za/training.htm)
• Research to Prevent Blindness (http://www.rpbusa.org/)Research to Prevent Blindness (http://www.rpbusa.org/)
• The Rehabilitation Research and Training Center on Blindness and LowThe Rehabilitation Research and Training Center on Blindness and Low
Vision (http://www.blind.msstate.edu/)Vision (http://www.blind.msstate.edu/)
• Florida Division of Blind Services (www.state.fl.us/dbs/index.shtml)Florida Division of Blind Services (www.state.fl.us/dbs/index.shtml)
• JAN's webpage (www.jan.wvu.edu/media/sight.html)JAN's webpage (www.jan.wvu.edu/media/sight.html)

Visual impairment 2

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Destaque

Destaque (6)

Semelhante a Visual impairment 2

Semelhante a Visual impairment 2 (20)

Mais de krishankasotia

Mais de krishankasotia (10)

Último

Último (20)

Visual impairment 2