Making Eye Health a Population Health Imperative Vision for Tomorrow (2016) / Chapter Skim
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2 Understanding the Epidemiology of Vision Loss and Impairment in the United States
2 Understanding the Epidemiology of Vision Loss and Impairment in the United States
Pages 55-134
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From page 55... ...
. Many eye diseases, conditions, and injuries affect vision, but they do not all contribute equally to the overall burden of vision loss in terms of numbers or populations affected nor the severity or the permanence of subsequent visual impairment.
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From page 56... ...
,2 cataracts, diabetic retinopathy, and glaucoma (Prevent Blindness, 2012b) .3 Refractive error alone is estimated to affect more than 48 million people ages 12 and older in the United States (Prevent Blindness, 2012g)
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From page 57... ...
Surrounding the macula, rods are more sensitive to light and are responsible for night vision, peripheral vision, and the ability to Vitreous gel Iris Optic nerve Cornea Macula Pupil Fovea Lens Retina Iris FIGURE 2-1 Anatomy of the human eye.
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From page 58... ...
Table 2-1 defines and provides TABLE 2-1 Common Visual System Conditions and Diseases and General Examples of Therapeutic Approaches for Improvement Disease or Affected Condition Structure Definition and General Approaches for Improvement Age-related Macula A degenerative eye disease that causes damage to the macular macula. "Dry" AMD is caused by the breakdown of degeneration light-sensitive cells in the macula, where as neovascular (AMD)
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From page 59... ...
Symptoms include seeing "floating" spots, blurred vision, and permanent vision loss. Treatments include control of systemic blood glucose, laser treatment for growth of new blood vessels, and eye injections to control macular edema.
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From page 60... ...
. In diseases such as diabetic retinopathy, glaucoma, and AMD, physiological changes related to the aging process alter the physical conditions under which light enters the eye or compromise the cellular function or neural pathways that relay information about the physical environment to the eye or the brain.
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From page 61... ...
Thus, the public health goal is to either prevent the impairment or to increase access to treatments and interventions that do correct for the vision impairment. This section presents estimates of overall prevalence for uncorrectable vision impairment only, along with the epidemiology for refractive error, amblyopia and strabismus, visual system injury, glaucoma, diabetic retinopathy, AMD, cataract, vision-threatening infection, and rare eye diseases and conditions.
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From page 62... ...
9 Prevent Blindness America pooled data from U.S. and international studies: Baltimore Eye Survey, Beaver Dam Eye Study, Blue Mountains Eye Study, Kongwa Eye Survey, Proyecto VER, Rotterdam Study, Salisbury Eye Evaluation Study, San Antonio Heart Study, San Luis Valley Diabetes Study, Visual Impairment Project, and Wisconsin Epidemiological Study of Diabetic Retinopathy.
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From page 63... ...
for uncorrectable vision impairment 3.22 2.91 Number of persons affected (in millions) for blindness 1.02 1.29 Total number of people with uncorrectable visual impairment and blindness 4.24 4.20 a Varma defines uncorrectable vision impairment as best-corrected visual acuity worse than 20/40 but better than 20/200 in the better-seeing eye; Varma defines blindness as best-corrected visual acuity of 20/200 or worse in the better-seeing eye.
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From page 64... ...
E3. TABLE 2-4 Prevalence and Number of Uncorrectable Visual Impairment and Blindness in Adults Ages 40 and Older by Age Group by Race/ Ethnicity and Gender in 2015 and Projected for 2050 in the United States Vision Impairment Blindness Age- Age Adjusted Adjusted Number in Prevalence Number in Prevalence Millions (%)
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From page 65... ...
. Women will continue to account for more cases of uncorrectable vision impairment and blindness than men, but this gap will close slightly from 1.33 to 1.3 women for every man in 2015 and FIGURE 2-2 Estimated numbers of persons with uncorrectable visual impairment (not including blindness)
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From page 66... ...
The number of Hispanics, African Americans, and Asians with uncorrectable vision impairment is also predicted to increase from 2015 to 2050, but the number of "other minorities" will remain relatively static. By 2050, Hispanics will surpass the number of African Americans with uncorrectable visual impairment.
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From page 67... ...
. The prevalence of visual impairment or amblyopia from uncorrected refractive error was more than 5 percent among African American and Hispanic preschoolers (ages 30 to 72 months)
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From page 68... ...
Geographic Distribution of Uncorrectable Vision Impairment and Blindness The overall burden of eye disease varies from state to state, and the pattern of highest and lowest prevalence varies by condition. Similarly, the distribution of uncorrectable visual impairment and blindness varies significantly by region and state.
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From page 69... ...
collected data from 19 states that fielded a special vision module during the 2006–2008 Behavioral Risk Factor Surveillance System (BRFSS) to estimate prevalence rates based on self-reported data among adults ages 65 and older for cataract, glaucoma, AMD, and diabetic retinopathy (CDC,
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From page 70... ...
Data from the American Community Survey from 2009 to 2013 show significant inter-county variation (between less than 1.0 percent to 18.4 percent) in the prevalence of severe vision loss among adults ages 12 Note: BRFSS data can be compared to Prevent Blindness data at www.visionproblems.
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From page 71... ...
Smaller geographic areas more closely align with service referral and delivery patterns 13 Thesurvey included people ages 18 and older. 14 Severe vision loss is defined in the American Community Survey as a positive self-reported response to the question, "Is this person blind or does s/he have serious difficulty seeing even when wearing glasses?
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From page 72... ...
, socioeconomic factors are associated with eye disease burden in a geographical area. Persons of all ages are at greater risk of developing eye disease if they are poor, have less education, or are unemployed (e.g., Ko et al., 2012; Roy, 2000; Roy and Affouf, 2006; Tielsch et al., 1991; Varma et al., 2004b)
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From page 73... ...
. This same study also found that students who were Hispanic or African American or attending a Title 1 school were more likely to have untreated refractive error as well.
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From page 74... ...
Figure 2-7 depicts the extent to which different eye diseases contribute to the prevalence of vision impairment and blindness among different racial and ethnic groups. Glaucoma and diabetic retinopathy account for a greater proportion of vision impairment and blindness among Hispanics and individuals of African ancestry than among non-Hispanic whites.
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From page 75... ...
Refractive Error in Adults Refractive error is the most common cause of vision impairment among adults in the United States. One estimate suggests that more than 48 million
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From page 76... ...
. One recent study found that older adults ages 65 to 84 with uncorrected refractive error and vision impairment16 16 Uncorrected refractive error was defined as visual acuity between 20/30 and 20/80 with out corrective lenses, and vision impairment was defined as post-refraction best-corrected visual acuity in both eyes of 20/30 or worse (Zebardast et al., 2015)
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From page 77... ...
Estimates for the projected number of cases of myopia between 2010 and 2050 indicate that, among whites, the number of cases will remain fairly stable, there will be a 1.5-fold increase of cases in African Americans, an almost 3-fold increase in the number of cases among Hispanics, and a 2.5-fold increase in cases among other minority 30% 25% 20% Prevalence 15% 10% 5% 0% 9 4 9 4 9 4 9 + −4 −5 −5 −6 −6 −7 −7 80 40 50 55 60 65 70 75 White Black Hispanic Other FIGURE 2-8 2010 U.S. age-specific prevalence rates for hyperopia by age (40 years and older)
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From page 78... ...
Refractive Error in Children Uncorrected refractive error can have a substantial impact on children. Uncorrected refractive error in young children can lead to physical, developmental, and academic problems.
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From page 79... ...
Racial and socioeconomic disparities have been examined as potential risk factors in uncorrected and undercorrected refractive error in both adult and pediatric populations. Qiu and colleagues (2014)
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From page 80... ...
Common Risk Factors for Refractive Error Risk factors for significant refractive error in childhood include parental history; having had prenatal, perinatal, or postnatal complications; and having had a significant neurodevelopmental condition (Jones-Jordan et al., 2010; O'Donoghue et al., 2015; Parssinen et al., 2014; Zadnik et al., 1994, 2015)
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From page 81... ...
. Other risk factors for refractive errors in children may include a sedentary lifestyle and maternal smoking during pregnancy (Borchert et al., 2011; O'Donoghue et al., 2015; Pan et al., 2012)
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From page 82... ...
Other related conditions, which are not examined in this chapter but are important to acknowledge, include anisometropia (significant differences in refractive error in both eyes) , convergence insufficiency (an eye muscle condition in which both eyes do not easily turn inward to see at near distances)
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From page 83... ...
. The Baltimore Pediatric Eye Disease Study (BPEDS)
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From page 84... ...
African Americans 2.1 0.08 McKean-Cowdin et al., Non-Hispanic white 3.2 1.8 2013 (MEPEDS) Asian 3.5 1.81 MEPEDS, 2008 African Americans 2.5 1.5 Hispanics 2.4 2.6 NOTE: BPEDS = Baltimore Pediatric Eye Disease Study Group; MEPEDS = Multi-Ethnic Pediatric Eye Disease Study Group.
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From page 85... ...
In adults, cataract is the most common ocular diagnosis after refractive error, and it accounts for the largest proportion of vision impairment in adults over age 40 (NEI/NIH, 2010d)
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From page 86... ...
Despite having lower prevalence rates of cataracts, minority populations are more likely to have vision impairment from untreated cataracts. For example, adult African American participants in the Baltimore Eye Survey were five times as likely as whites to have unoperated "senile" cataracts (Sommer et al., 1991; Zambelli-Weiner et al., 2012)
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From page 87... ...
, which are all considered to be risk factors for cataract formation; however, the primary role of these factors in cataract formation is less clear (Cheung and Wong, 2007; Leske et al., 1999; Park and Lee, 2015; Yu et al., 2014)
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From page 88... ...
. Other potential risk factors for cataracts, such as arthritis, the extended use of calcium channel blockers, thyroid hormone use, and corticosteroid use are in early stages of investigation.
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. A 2009 study found that workers who are more likely to have eye injuries have less than a high-school education, are nonHispanic whites, are self-employed, and live in the Midwest region (Forrest and Cali, 2009)
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From page 90... ...
. Patients with TBI may experience a range of visual symptoms and disorders, including problems with visual acuity, visual fields, oculomotor function, among others (Brahm et al., 2009; Cockerham et al., 2009; Goodrich et al., 2013; Magone et al., 2014; Rosner et al., 2016)
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From page 91... ...
. Infections and Vision Impairment The eye and vision health of children and adults can be compromised by infection, including eye infections, systemic infections that can potentially affect the development or function of the visual system, and nosocomial infections following eye surgery.
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Neonatal conjunctivitis, may cause red eyes, swollen eye lids, and discharge of pus. Usually a minor eye infection, in some cases conjunctivitis can lead to scarring, eye damage, or vision loss.
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From page 93... ...
In some cases, scar tissue may form and contract, causing retinal detachment and potentially permanent vision loss. Left unchecked, diabetic retinopathy can also lead to diabetic macular edema (DME)
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Common Risk Factors for Diabetic Retinopathy By definition, individuals with diabetic retinopathy have diabetes. Hyperglycemia, hypertension, and dyslipidemia (an abnormal amount of lipids)
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From page 95... ...
. Other possible mechanisms related to obesity for diabetic retinopathy include increased vasoproliferative factors (e.g., vitreous vascular endothelial growth factor [VEGF]
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From page 96... ...
. Another study found that visual impairment from glaucoma was 15 times more likely among African Americans than whites (Muñoz et al., 2000)
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From page 97... ...
Common Risk Factors for Glaucoma Certain physical and medical conditions are associated with increased risk of glaucoma. Physiological risk factors for developing glaucoma include an elevated IOP, greater cup-to-disc ratio, and thin central corneal measurement (Coleman and Miglior, 2008; Gordon et al., 2002)
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From page 98... ...
. Age-Related Macular Degeneration AMD is a progressive, chronic condition that affects the retina, with most vision loss occurring in later stages of the disease (Lim et al., 2012)
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From page 99... ...
. Common Risk Factors for AMD A number of environmental, behavioral, genetic, and other physical conditions have been associated with the risk of AMD.
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. One study found synergistic effects among small groups of risk factors, such as obesity and alcohol, obesity and smoking, alcohol and high cholesterol, high cholesterol and smoking, and smoking and family history (La Torre et al., 2013)
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From page 101... ...
In other disease states, such as neovascular age-related macular degeneration or diabetic retinopathy, gene therapy has the potential to alter the production or function of existing cell proteins, such as vascular endothelial growth factor, which trigger conditions in the eye that can lead to vision loss (Campbell et al., 2016)
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From page 102... ...
3. Correctable (e.g., vision impairment from diseases and conditions for which available treatments can eliminate or correct for exist ing vision impairment, such as uncorrected refractive error and cataracts)
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From page 103... ...
In addition to interventions that target specific forms of vision loss, the promotion of general social, environmental, and political determinants of health could also improve eye and vision health. For example, policies and interventions that promote healthy eating and reduce exposure to UV light could affect the prevalence of diabetic retinopathy, AMD, or cataracts.
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From page 104... ...
These topics are discussed at length in Chapters 5, 6, 7, and 8. Correctable Vision Impairment Vision impairment associated with uncorrected refractive error can easily be avoided by correcting the refractive error with eyeglasses, contacts, or laser surgery (when appropriate)
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Modifiable Vision Impairment Comprehensive eye exams are important to ensure early detection and treatment of many eye diseases and conditions that cause modifiable vision impairment, such as diabetic retinopathy, glaucoma, and neovascular AMD (Sloan et al., 2014)
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From page 106... ...
However, it is important to note that, when left untreated, modifiable vision impairment can progress to uncorrectable vision impairment (as with glaucoma, neovascular AMD, amblyopia, and diabetic retinopathy)
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From page 107... ...
To understand the magnitude of the undiagnosed and correctable visual impairment that currently exists in the United States, the committee commissioned an analysis to establish the preventable burden of vision impairment in the United States from five conditions (diabetic retinopathy, glaucoma, refractive error, cataracts, and age-related macular degeneration)
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From page 108... ...
Undiagnosed cases were identified by subtracting the total number of identified cases in NHANES from overall prevalence using VPUS. In the case of uncorrected refractive error, visual acuity tests in NHANES data were used to identify the proportion of individuals with uncorrected refractive error.
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From page 109... ...
wrote that "because refractive error's impact on visual acuity can be mitigated relatively easily, it has sometimes been overlooked as an important cause of visual impairment" (p.
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From page 110... ...
. Similarly, the MEPEDS study found that the prevalence of poor visual acuity or amblyopia development due to uncorrected refractive error was 4.3 percent among African American and 5.3 percent among Hispanic preschoolers (ages 30 to 72 months)
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, net economic savings over the next 10 years would yield an average savings of more than $87.7 billion annually in direct and indirect costs, a remarkable 40-fold return for treatment of uncorrected refractive error. Undercorrection of refractive error is also a concern.
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From page 112... ...
Uncorrected refractive error and correctable cataracts should be a major component of any comprehensive population health approach to improving overall eye and vision health and health equity in the United States, especially among children. KEY KNOWLEDGE AND RESEARCH GAPS Despite the important contributions that existing literature has made to advance knowledge about eye and vision health in the United States, many key information gaps still remain.
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From page 113... ...
. The committee stresses that efforts to expand knowledge about the epidemiology of vision impairment should balance the more common with rarer eye diseases and conditions in any population health approach to combat the immediate and long-term impacts of vision loss.
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From page 114... ...
Using the best available data and methodological approaches to explore the epidemiology in the United States, it is clear that eye health and vision impairment constitute a major public health imperative -- one which can be alleviated through a better understanding of populations affected, risk factors underlying specific disorders, and barriers to care that result in an unmet need for diagnosis and treatment. Assessing the prevalence and distribution of vision impairment across populations in the United States is critical to developing effective public health policy.
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From page 115... ...
2005. Risk factors for the incidence of advanced age-related macular degeneration in the Age-Related Eye Disease Study (AREDS)
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2011. Risk factors associated with incident cataracts and cataract surgery in the Age-Related Eye Disease Study (AREDS)
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From page 117... ...
2005. Risk factors for the incidence of advanced age-related macular degeneration in the Age-Related Eye Disease Study (AREDS)
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2011. Risk factors associated with childhood strabismus: The Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease studies.
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2014. Laser photocoagulation for proliferative diabetic retinopathy.
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2009. Prevalence of refractive error among preschool children in an urban population: The Baltimore Pediatric Eye Disease Study.
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2002. Risk factors for age-related macular degeneration: An update.
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From page 122... ...
2013. Prevalence and risk factors for diabetic retinopathy: The Korea National Health and Nutrition Examination Survey, 2008–2011.
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2008. Prevalence and risk factors of diabetic retinopathy in a multi-racial under served population.
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From page 124... ...
2009. Prevalence and causes of visual impairment in African-American and His panic preschool children: The Multi-Ethnic Pediatric Eye Disease Study.
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From page 125... ...
2006. Development of cataract and associated risk factors: The Visual Impairment Project.
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2014. Risk factors for proliferative diabetic retinopathy in a Latino American population.
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From page 127... ...
R Tien, and the Pediatric Eye Disease Investigator Group.
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From page 128... ...
2000. Diabetic retinopathy in African Americans with type 1 diabetes: The New Jersey 725: II.
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2016. Risk factors for progres sion of early age-related macular degeneration in Koreans.
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From page 130... ...
2007. Biologic risk factors associated with diabetic retinopathy: The Los Angeles Latino Eye Study.
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From page 131... ...
2008. Prevalence and risk factors for diabetic retinopathy: The Singapore Malay Eye Study.
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2012. Global prevalence and major risk factors of diabetic retinopathy.
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2012. Vision health disparities in the United States by race/ethnicity, education, and economic status: Findings from two nationally representative surveys.
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