Visual ImpairmentIntroductionFactors Affecting Visual Function and Their TreatmentDefinition of Legal BlindnessStatisticsSlide 6Slide 7Prevalence of Blindness by Age and Race (US)Slide 9CataractsCorneal DiseaseMacular DegenerationSlide 13Diabetic RetinopathySlide 15GlaucomaSlide 17AlbinismRetinitis PigmentosaSlide 20Peripheral Visual Field Loss from Strokes or TumorsGeneral Vocational ImplicationsResourcesVisual ImpairmentMedical and Psychosocial Aspects of DisabilityIntroduction•Vision impairment affects a significant proportion of middle-aged and older Americans –1 in 6 adults (17%), age 45 and older, representing 13.5 million Americans, reports some form of vision impairment even when wearing glasses or contact lenses •The prevalence of visual impairments increase with age –15% of people 45-64 –17% of people 65-74 –26% of people 75 and olderFactors Affecting Visual Function and Their Treatment•Visual Acuity - ability to see "detail" –Measured using testing distance/letter size –Normal is 20/20 –Limitation on acuity level is generally determined by the spacing of the cones –Treatment: glasses or some form of magnification •Visual Field - a person's peripheral vision –Scotoma - loss of vision in an area •Contrast •Lighting and Glare –Often, too much light can be as detrimental as not enoughDefinition of Legal Blindness•WHO Definition: Best-corrected visual acuity of less than 6/120 (<20/400) in the better-seeing eye.•US Definition: Best-corrected visual acuity of 6/60 or worse (<20/200) in the better-seeing eye. OR •Peripheral visual field is restricted to 20° or less in the widest meridian of the better eye •(US Definition of Low Vision: best-corrected visual acuity of 6/12 (<20/40) in better-seeing eye.)Statistics•In 2000 there were 937,000 blind Americans older than 40 (0.78%)•2,400,000 with low vision (1.98%)•Thus, there were 3.3 million Americans aged 40 or more with a visual impairment in 2000The Eye Diseases Prevalence Research Group (2004). Causes and prevalence of visual impairment among adults in the United States. Archives of Ophthalmology, 122, 477-485.The Eye Diseases Prevalence Research Group, Arch Ophthalmol 2004;122:477-485.AMD=age-related macular degeneration, DR=diabetic retinopathyCauses 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 retinopathyCauses 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/ethnicityPrevalence of Blindness by Age and Race (US)White Black Hispanic40-49 0.12 0.18 0.0550-54 0.10 0.34 0.1055-59 0.11 0.52 0.1660-64 0.15 0.81 0.2665-69 0.23 1.25 0.4170-74 0.43 1.93 0.6475-79 0.93 2.96 0.99>80 6.82 6.85 2.42Cataracts•A cataract is opacity or clouding of the lens that may develop as a result of aging, trauma, hereditary factors, birth defects, or diabetes •Cataracts are a normal part of aging –Approximately 50% of Americans between 65 and 74 and 70% over age 75 have cataracts •Prevalence factors –Caucasians are three times as likely as African-Americans to develop cataracts –Smokers have a 60% increase –Those taking medication for gout are twice as likely to develop cataracts •The greater the progression of the cataract, the greater the visual impairment from the effects of glare, loss of contrast, and decreased visual acuity •Normally, cataracts are successfully treated with surgery •Assuming no complications, there should be no vocational implications following cataract surgery No cataractcataractCorneal Disease•The cornea is a structure that is prone to dystrophies, deposition, noninflammatory progressive thinning (keratoconus), infection, viral diseases, and trauma •Interference with corneal integrity can result in a blurred or distorted image on the retina –May experience severe glare, cloudy vision, and reduced acuity •Treatment –Keratoplasty is the primary method of restoring vision for an individual with a diseased, irregular, or scarred cornea - procedure involves transplanting a healthy cornea from a compatible donor –Recently, lasers have been used to treat some corneal problems •Vocational Implications –Vocational goals will be dependent on the degree to which the retinal image is compromisedMacular Degeneration•Macular degeneration is caused by degenerative changes to the macular area of the retina that result in atrophy, hemorrhage, exudates, fibrovascular scars, or cyst formations •Risk factors –Caucasian –Family history –High blood pressure or a history of hypertension –Light iris color –Smoking •Functional Presentation –Visually manifested as distortions, a decrease in the visual acuity, a decrease in color recognition, a loss of contrast, or an absolute or relative area of no vision (scotoma) –Reading may become increasingly difficult and driving may have to be discontinuedMacular Degeneration•Treatment –Laser treatment can sometimes be used to slow the progression of the disease –Other treatments that have been investigated (but not yet established) include the use of radiation, laser treatment of drusen (small globular pathological growths formed on optic papilla or on Descemet's membrane), photodynamic therapy, submacular surgery, retinal cell transplantation, and the use of vascular endothelial growth factor •Vocational Implications –Driving –Vision rehabilitation program may be needed before being able to return to work •Accommodations/Assistive Technology –Lenses and magnification devices –Talking books –Bold, felt-tip pens –Talking clocks (and other talking devices and appliances)Diabetic Retinopathy•Diabetes accounts for about 5,000 new cases of blindness each year and people with diabetes have a 25 times greater risk for blindness than the general population –Approximately 40% of people with diabetes have diabetic retinopathy •Functional Presentation –Fluctuating or severely decreased visual acuity –Problems due to glare, reduced contrast sensitivity, and various types of visual field problems –May have transient episodes of diplopiaDiabetic Retinopathy•Vocational Implications –Rehabilitation considerations must include not only vision but also the effect of diabetes on