Objective
To estimate the levels of self-reported access of eye care services in the nation.
Methods
We analyzed data from the 2002 National Health Interview Survey (30 920 adults aged ≥18 years). We estimated the number of US adults at high risk for serious vision loss and assessed factors associated with the use of eye care services.
Results
An estimated 61 million adults in the United States were at high risk for serious vision loss (they had diabetes, had vision or eye problems, or were aged ≥65 years); 42.0% of the 78 million adults who had dilated eye examinations in the past 12 months were among this group. Among the high-risk population, the probability of having a dilated eye examination increased with age, education, and income (P<.01). The probability of receiving an examination was higher for the insured, women, persons with diabetes, and those with vision or eye problems (P<.01). Approximately 5 million high-risk adults could not afford eyeglasses when needed; being female, having low income, not having insurance, and having vision or eye problems were each associated with such inability (P<.01).
Conclusions
There is substantial inequity in access to eye care in the United States. Better targeting of resources and efforts toward people at high risk may help reduce these disparities.
In 2000, approximately 3.3 million American adults aged 40 years or older were visually impaired (best-corrected visual acuity <20/40 in the better-seeing eye) mainly because of potentially preventable or treatable eye diseases such as age-related macular degeneration, cataract, diabetic retinopathy, or open-angle glaucoma.1 Additionally, more than 11 million Americans aged 12 years and older needed refractive correction.2 Visual impairment and eye diseases are associated with increased morbidity3 and mortality4-13 as well as decreased quality of life.14-17 These problems affect people's activities of daily living,17-19 cause falls and injuries,20-22 and lead to depression and social isolation.23-26
By 2020, the number of people with visual impairment and eye diseases could increase by 50% or more.1,27-30 From a patient's perspective, access to eye care is increasingly attached to the use of eye care services. Not surprisingly, use of—and thus “realized” or actual access to—eye care services is uneven in the United States, a special concern because of the growing demand for vision and eye care with a growing older population, the asymptomatic nature of many eye diseases in their early, treatable stages, and the prevalence of visual problems such as self-reported trouble or difficulty seeing. In this study, we estimated the levels of realized access to eye care at the national level and explored existing disparities and potential barriers to care. We paid special attention to the population at high risk for serious vision loss (persons with self-reported diabetes, with vision or eye problems, or aged ≥65 years), where preventive or regular eye care services are recommended.31-33
We used vision data from the 2002 National Health Interview Survey (NHIS). Conducted annually by the National Center for Health Statistics, the NHIS uses a stratified, cross-sectional, multistage probability sample to make estimates for the civilian noninstitutionalized population. The methods of the NHIS have been described previously.34,35 Briefly, the 2002 NHIS data were collected continuously through a personal household interview in the 50 states and the District of Columbia. Families in interviewed households provided basic health and demographic information for all members of the family. One adult and 1 child were randomly selected from each family for a more detailed health profile. In 2002, household interviews were completed for 93 386 persons living in 36 831 families who represented 36 161 households.36 We restricted our analysis to the adult sample (n = 31 044). The conditional response rate of sample adults was 84.4%, and their final response rate was 74.4%.37 In this study, we analyzed data from 30 920 adults aged 18 years and older using a well-established behavioral access model to guide the selection of variables.38 Respondents who were blind or unable to see at all were not included in the analysis (n = 124).
Dependent variables in the study included respondent self-report of having visited an eye doctor in the past 12 months, having a dilated eye examination in the past 12 months, and not being able to afford eyeglasses when needed. These measures were chosen because visits to the eye doctor and receipt of a dilated eye examination capture differential elements of health care use while inability to afford eyeglasses also addresses the issue of financial barriers and the impact of reduced visual acuity due to uncorrected refractive error on vision-related quality of life.
Independent variables included age (ages 18-44, 45-64, and ≥65 years), sex, race or ethnicity (white [white non-Hispanic], African American [black non-Hispanic], Hispanic, and others [others non-Hispanic]), marital status, education (<high school, high school, and >high school), income (poverty income ratio <1, 1≤poverty income ratio<2, and poverty income ratio ≥2), health insurance, diabetes, vision or eye problems, and region (Northeast, Midwest, South, and West). Insurance groupings were collapsed from more detailed categorizations used in the NHIS. Respondents who had only public insurance (such as Medicare, Medicaid, Indian Health Service, military insurance, or other public or government insurance) were grouped into the public category, and the private group was for those with private coverage only. Respondents with both public and private coverage were categorized as both, and those who reported no coverage were categorized as none. Additionally, as the insurance status of persons aged 65 years and older may be unique because of Medicare, we further stratified this cohort (those aged ≥65 years) by 3 categories with a method previously used by the National Center for Health Statistics and assessed the influence of Medicare on eye care use.39 These categories were Medicare only, Medicare plus other public coverage, and private (with or without Medicare). For those between the ages of 18 and 64 years, the 3 insurance categories used were public only, private (with or without public), and uninsured.
By high risk, we sought to identify the following: (1) those who are aged 65 years or older and thus have a much greater prior probability of having a significant chronic ocular condition based on the results of population-based surveys; (2) those who have a systemic condition (self-reported diabetes mellitus excluding borderline or gestational diabetes) associated with a significantly greater risk of blindness40; and (3) those who already have an ocular disease or condition (age-related macular degeneration, cataract, diabetic retinopathy, glaucoma, or eye injury) that, if undetected or untreated, could result in permanent vision loss or those who report visual symptoms of “trouble seeing even with glasses or contact lenses” or activity limitations due to vision problems. We included this group of self-reported visual symptoms and activity limitations because other studies have shown that symptoms such as trouble seeing or blurred vision are independently associated with greater decrements in activities of daily living and instrumental activities of daily living as well as lower general health states as measured by the 36-item Short-Form Health Survey.41,42 As such, this captures a larger group of persons who might well benefit from interventions to prevent further vision loss and activity limitations.
To make estimates representative of the civilian noninstitutionalized population, we used SAS statistical software version 9.1 (SAS Institute, Cary, NC) and SUDAAN statistical software version 9.0 (Research Triangle Institute, Research Triangle Park, NC) to adjust for the complex design of the sample, the problem of nonresponse, and the probability of selection. We used Wald χ2 tests to explore the bivariate relationships. Multivariate logistic regressions were used to estimate the probability of visiting an eye doctor, having a dilated eye examination, and being unable to afford eyeglasses when needed after controlling for all other independent variables. Predictive margins and their standard errors from logistic regression models were estimated using Taylor linearization.43
Of the respondents, 16.0% were aged 65 years and older, 6.5% had diabetes, and 19.5% had vision or eye problems (Table 1). Compared with the low-risk group, those at high risk tended to have less education and not as much income (as expressed by the poverty income ratio).
Of the estimated 61 million adults in the United States classified as being at high risk for serious vision loss, we estimated that only half visited an eye doctor in the past 12 months and half had a dilated eye examination (Figure; we assume that these groups overlapped very much). By comparison, of the estimated 144 million people classified as not being at high risk, about a third visited an eye doctor and a third had a dilated eye examination (again, we assume great overlap). We found that of an estimated 78 million people with dilated eye examinations, 42.0% were at high risk and 58.0% were not at high risk. We also found that 1 in 12 persons at high risk and 1 in 25 not at high risk could not afford eyeglasses when needed.
Results from multivariate regression among the general population (Table 2) showed significant relationships between the use of eye care and various individual and systematic descriptors. Controlling for all other variables in the model, the probability of visiting an eye doctor and the probability of having a dilated eye examination increased with age and education (P<.01). In addition, having high income, having health insurance, being female, having diabetes, or having vision or eye problems increased the probability of visiting an eye doctor and having the eye examination (P<.01). Inability to afford eyeglasses was associated with being unmarried, being female, having low income, being without insurance, having diabetes, or having vision or eye problems (P<.01). Although people at high risk for serious vision loss were more likely than the general population to receive eye care services (visits, examinations), health disparities among the high-risk population remained clear and crucial (Table 3). In this population (unlike the population generally), those who were married were more likely to visit an eye doctor (P<.05) or have a dilated eye examination (P<.01) than those who were not married, again when controlling for all other variables in the model.
Among adults younger than 65 years, those with private or public insurance had a higher probability of visiting an eye doctor, having a dilated eye examination, and being able to afford eyeglasses than those without insurance (Table 4). In contrast, we did not find significant differences for visits and examinations between persons with public and private coverage, but there was a significant difference between these groups in being able to afford eyeglasses. Among persons aged 65 years and older, those with private coverage (with or without Medicare) were more likely to have had visits and examinations and were better able to afford eyeglasses than were those with Medicare only.
As the baby boomers age, ensuring access to chronic care and preventive services such as vision and eye care has become a major public health concern.44-46 Appropriately, Healthy People 201047 includes 10 objectives for vision that can be used to monitor the burden of visual impairment and levels of eye care in the nation. Our study systematically explored access to eye care at the national level. We found that only 54.8% of adults with vision or eye problems and 62.9% of adults with diabetes had a dilated eye examination in the past 12 months. The rates of eye doctor visits and dilated eye examinations were higher among our high-risk group than in those who did not have those characteristics. Greater access to eye care services was also associated with age, sex, race or ethnicity, education, income, health insurance, and region. These results are supported by the findings in population-based studies such as the Beaver Dam Eye Study48 or the Salisbury Eye Evaluation Project,49 which also found greater rates of use among those with ocular conditions or vision problems, diabetes, and additional health insurance.
One of the 2 major goals set by Healthy People 201047 is to eliminate health disparities between the sexes and by race or ethnicity and socioeconomic level. In this study, we found considerable differences by sex in realized access to eye care services, with women faring better than men in visiting eye doctors and having dilated eye examinations. We also found that African Americans and Hispanic persons were significantly less likely to visit an eye doctor than were white persons, which calls for continued efforts to improve the access to eye care services among minority populations as found in other studies.49-52 These findings from this national sample are consistent with those in an article53 on the Medicare population with diabetes that found that men and African Americans used eye care services less.
Not surprisingly, we found that adults with higher education and those with greater incomes were relatively more likely to use eye care services. In addition, our findings suggest that the uninsured were much less likely to receive preventive eye care in the form of eye doctor visits or dilated eye examinations than were the insured, which is consistent with a recent article54 on the use of other recommended preventive services. Using data from the 2000 Behavioral Risk Factor Surveillance System, which also relies on self-reports, Nelson et al51 obtained findings consistent with ours, as they found that uninsured persons with diabetes were less likely to have an annual dilated eye examination and to undergo other tests related to diabetes management. Our findings are also consistent with data from 5 states in the optional vision module offered by the Behavioral Risk Factor Surveillance System, which indicated that “no reason to go” and “cost or insurance” were the top 2 reasons for people not to see an eye care professional.55 Therefore, in addition to the widely recognized issue of awareness regarding access to eye care,56 we see that health insurance remains a critical factor.
Many conditions causing visual impairment and blindness are often asymptomatic in their early, treatable stages. Timely examination of vision is recommended for people with vision or eye problems, and a yearly examination is recommended for those with diabetes or at older ages (ages ≥65 years).31-33 Screening the vision of adults aged 65 years and older is listed among the top 10 priorities for clinical preventive services (as determined by the National Commission on Prevention Priorities).57 However, we found that not much more than half of those at high risk for serious vision loss had visited an eye doctor in the past 12 months; the estimate for a dilated eye examination in that period was similar. Of particular concern is that even though diabetes is the leading cause of legal blindness in the United States,33 1 in 3 adults with diabetes did not have a dilated eye examination in the preceding year, a finding that has remained consistent across numerous studies for many years.51,58
Adults with vision or eye problems or with diabetes used significantly more eye care services than their counterparts without these problems. The age-adjusted prevalence of visual impairment due to refractive error was found to be higher among persons with diabetes than persons without diabetes (unpublished data, Centers for Disease Control and Prevention, 1999-2004). Even so, we found that 10.5% of persons with vision or eye problems and 8.8% of those with diabetes could not afford eyeglasses when needed as compared with 4.2% of persons without vision or eye problems and 5.2% of persons without diabetes. Thus, the people who needed the visual aid more were the ones less likely to be able to afford these aids. A recent article with data on the general population from the National Eye Institute2 and newly released data on people with diabetes from the Centers for Disease Control and Prevention59 both call for increased public health interventions in reducing the burden of correctable visual impairment due to refractive error among the general public and especially persons with diabetes.
There were several limitations to our study. First, our definition of high-risk population does not account for factors such as family history and genetic features; relying on this definition may have caused us to underestimate the number of high-risk adults. Alternative definitions of high risk would include characterization along racial or ethnic lines or by socioeconomic status. In our multivariate analyses, we included these as independent factors and found, as expected, that those known from prior studies to be at higher risk indeed had lower rates of visits to the eye doctor and dilated eye examinations. We included these in a multivariate analysis as opposed to subgroup analyses because these are sociodemographic characteristics already known to be associated with reduced eye care use. Our current study instead evaluates patients on the basis of known medical and ocular conditions as well as demographic characteristics (age) and patient-centered symptoms known to have higher levels of use and found not only that was there a substantial gap in care received but that the impact of known characteristics persisted in this select group who would most benefit from regular care.
Second, our study is based on self-reported data. Inevitably, there is some degree of difference between self-reported outcomes and clinical or measurable outcomes, but the survey results from the NHIS are generally considered valid and reliable.34,35
Third, the institutionalized population (eg, residents of nursing homes) and military groups were not included in the survey. Also, there was some nonresponse, especially for income information. Still, population-based surveys are an effective way to systematically monitor and evaluate access to eye care, and the NHIS is considered one of the best available national samples and has a relatively high response rate, which increases its generalizability.
A fourth concern is our somewhat puzzling result that some estimates were higher for a dilated eye examination than for a visit to an eye doctor. Although the reasons behind this unexpected outcome are unknown and potentially complicated (eg, eye care services provided by a primary care physician, recall bias in examinations, inability to understand the survey questions, vision screening by people who would not be identified as eye doctors), we can speculate that awareness of what was going on during the visit(s) of interest may have been at the core of the problem. Among persons who had not finished high school, we found that the percentage for visiting an eye doctor was well below the percentage for receiving a dilated eye examination, but among those with more than a high school education, we found a marginal difference in the other direction. The definition of dilation in the wording of the question (“ . . . dilated? This would have made you temporarily sensitive to bright light”) likely contributed to this finding as well. Finally, we are concerned that although access to medical care is a multidimensional concept,38,60-64 we could not explore information on many of the factors that might contribute to whether US adults obtain reasonable access to eye care. Owing to the limitations of the data set, we could not explore information on, inter alia, urban or rural residence, the characteristics of providers, and patient satisfaction. Future research might benefit by incorporating these measures.
To summarize, despite the recent emphasis on vision in Healthy People 2010,47 there is still substantial inequity in realized access (ie, actual use) to eye care in the United States. Of the estimated 61 million adults in the United States classified as being at high risk for serious vision loss, we found that just slightly more than half had received a dilated eye examination in the past 12 months. We also found that 1 in 12 high-risk persons could not afford eyeglasses when needed. Better targeting of resources and efforts toward people at high risk for whom cost-effective interventions exist may help reduce these disparities.
Correspondence: Xinzhi Zhang, MD, PhD, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, 4770 Buford Hwy NE (K-10), Atlanta, GA 30341-3727 (xzhang4@cdc.gov).
Submitted for Publication: November 4, 2006; accepted December 6, 2006.
Author Contributions: Dr Zhang had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Financial Disclosure: None reported.
Disclaimer: The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.
1.Eye Diseases Prevalence Research Group, Causes and prevalence of visual impairment among adults in the United States.
Arch Ophthalmol 2004;122477- 485
PubMedGoogle Scholar 2.Vitale
SCotch
MFSperduto
RD Prevalence of visual impairment in the United States.
JAMA 2006;2952158- 2163
PubMedGoogle Scholar 3.Lee
DJGomez-Marin
OLam
BLZheng
DDCaban
A Visual impairment and morbidity in community-residing adults: the national health interview survey 1986-1996.
Ophthalmic Epidemiol 2005;1213- 17
PubMedGoogle Scholar 4.Hennis
AWu
SYLi
XNemesure
BLeske
MC Lens opacities and mortality: the Barbados Eye Studies.
Ophthalmology 2001;108498- 504
PubMedGoogle Scholar 5.Hiller
RPodgor
MJSperduto
RDWilson
PWChew
EYD'Agostino
RB High intraocular pressure and survival: the Framingham Studies.
Am J Ophthalmol 1999;128440- 445
PubMedGoogle Scholar 6.Klein
RMoss
SEKlein
BEDeMets
DL Relation of ocular and systemic factors to survival in diabetes.
Arch Intern Med 1989;149266- 272
PubMedGoogle Scholar 7.Klein
RKlein
BEMoss
SE Age-related eye disease and survival: the Beaver Dam Eye Study.
Arch Ophthalmol 1995;113333- 339
PubMedGoogle Scholar 8.Lam
BLLee
DJGomez-Marin
OZheng
DDCaban
AJ Concurrent visual and hearing impairment and risk of mortality: the National Health Interview Survey.
Arch Ophthalmol 2006;12495- 101
PubMedGoogle Scholar 9.Lee
DJGomez-Marin
OLam
BLZheng
DD Visual acuity impairment and mortality in US adults.
Arch Ophthalmol 2002;1201544- 1550
PubMedGoogle Scholar 10.McCarty
CANanjan
MBTaylor
HR Vision impairment predicts 5 year mortality.
Br J Ophthalmol 2001;85322- 326
PubMedGoogle Scholar 11.Thompson
JRSparrow
JMGibson
JMRosenthal
AR Cataract and survival in an elderly nondiabetic population.
Arch Ophthalmol 1993;111675- 679
PubMedGoogle Scholar 12.Wang
JJMitchell
PSimpson
JMCumming
RGSmith
W Visual impairment, age-related cataract, and mortality.
Arch Ophthalmol 2001;1191186- 1190
PubMedGoogle Scholar 13.West
SKMunoz
BIstre
J
et al. Mixed lens opacities and subsequent mortality.
Arch Ophthalmol 2000;118393- 397
PubMedGoogle Scholar 14.Brown
MMBrown
GCSharma
SLandy
JBakal
J Quality of life with visual acuity loss from diabetic retinopathy and age-related macular degeneration.
Arch Ophthalmol 2002;120481- 484
PubMedGoogle Scholar 15.Brown
MMBrown
GCSharma
SBusbee
B Quality of life associated with visual loss: a time tradeoff utility analysis comparison with medical health states.
Ophthalmology 2003;1101076- 1081
PubMedGoogle Scholar 16.Clemons
TEChew
EYBressler
SBMcBee
W National Eye Institute Visual Function Questionnaire in the Age-Related Eye Disease Study (AREDS): AREDS Report No. 10.
Arch Ophthalmol 2003;121211- 217
PubMedGoogle Scholar 17.Vu
HTKeeffe
JEMcCarty
CATaylor
HR Impact of unilateral and bilateral vision loss on quality of life.
Br J Ophthalmol 2005;89360- 363
PubMedGoogle Scholar 18.Rudberg
MAFurner
SEDunn
JECassel
CK The relationship of visual and hearing impairments to disability: an analysis using the longitudinal study of aging.
J Gerontol 1993;48M261- M265
PubMedGoogle Scholar 19.West
SKMunoz
BRubin
GS
et al. Function and visual impairment in a population-based study of older adults: the SEE project: Salisbury Eye Evaluation.
Invest Ophthalmol Vis Sci 1997;3872- 82
PubMedGoogle Scholar 20.Ivers
RQCumming
RGMitchell
PAttebo
K Visual impairment and falls in older adults: the Blue Mountains Eye Study.
J Am Geriatr Soc 1998;4658- 64
PubMedGoogle Scholar 21.Legood
RScuffham
PCryer
C Are we blind to injuries in the visually impaired? a review of the literature.
Inj Prev 2002;8155- 160
PubMedGoogle Scholar 22.Ivers
RQNorton
RCumming
RGButler
MCampbell
AJ Visual impairment and risk of hip fracture.
Am J Epidemiol 2000;152633- 639
PubMedGoogle Scholar 23.Rovner
BWGanguli
M Depression and disability associated with impaired vision: the MoVies Project.
J Am Geriatr Soc 1998;46617- 619
PubMedGoogle Scholar 24.Bazargan
MHamm-Baugh
VP The relationship between chronic illness and depression in a community of urban black elderly persons.
J Gerontol B Psychol Sci Soc Sci 1995;50S119- S127
PubMedGoogle Scholar 25.Carabellese
CAppollonio
IRozzini
R
et al. Sensory impairment and quality of life in a community elderly population.
J Am Geriatr Soc 1993;41401- 407
PubMedGoogle Scholar 26.Appollonio
ICarabellese
CFrattola
LTrabucchi
M Effects of sensory aids on the quality of life and mortality of elderly people: a multivariate analysis.
Age Ageing 1996;2589- 96
PubMedGoogle Scholar 27.Eye Diseases Prevalence Research Group, Prevalence of open-angle glaucoma among adults in the United States.
Arch Ophthalmol 2004;122532- 538
PubMedGoogle Scholar 28.Eye Diseases Prevalence Research Group, The prevalence of diabetic retinopathy among adults in the United States.
Arch Ophthalmol 2004;122552- 563
PubMedGoogle Scholar 29.Eye Diseases Prevalence Research Group, Prevalence of age-related macular degeneration in the United States.
Arch Ophthalmol 2004;122564- 572
PubMedGoogle Scholar 30.Eye Diseases Prevalence Research Group, Prevalence of cataract and pseudophakia/aphakia among adults in the United States.
Arch Ophthalmol 2004;122487- 494
PubMedGoogle Scholar 33.Fong
DSAiello
LGardner
TW
et al. Retinopathy in diabetes.
Diabetes Care 2004;27
((suppl 1))
S84- S87
PubMedGoogle Scholar 34.National Center for Health Statistics, National Health Interview Survey: research for the 1995-2004 redesign.
Vital Health Stat 2 1999;
((126))
1- 119
PubMedGoogle Scholar 35.National Center for Health Statistics, Design and estimation for the National Health Interview Survey, 1995-2004.
Vital Health Stat 2 2000;
((130))
1- 31
PubMedGoogle Scholar 36.Schiller
JSBernadel
L Summary health statistics for the US population: National Health Interview Survey, 2002.
Vital Health Stat 10 2004;
((220))
1- 101
PubMedGoogle Scholar 37.Lethbridge-Cejku
MSchiller
JSBernadel
L Summary health statistics for US adults: National Health Interview Survey, 2002.
Vital Health Stat 10 2004;
((222))
1- 151
PubMedGoogle Scholar 38.Aday
LAAndersen
R A framework for the study of access to medical care.
Health Serv Res 1974;9208- 220
PubMedGoogle Scholar 39.Schoenborn
CAVickerie
JLPowell-Griner
E Health characteristics of adults 55 years of age and over: United States, 2000-2003.
Adv Data 2006;
((370))
1- 31
PubMedGoogle Scholar 41.Kington
RRogowski
JLillard
LLee
PP Functional associations of “trouble seeing.”
J Gen Intern Med 1997;12125- 128
PubMedGoogle Scholar 42.Lee
PPSpritzer
KHays
RD The impact of blurred vision on functioning and well-being.
Ophthalmology 1997;104390- 396
PubMedGoogle Scholar 44.Holahan
JCook
A Changes in economic conditions and health insurance coverage, 2000-2004.
Health Aff (Millwood) 2005;W5-498- W5-508[published online ahead of print November 1, 2005]doi:10.1377/hlthaff.W5.498
Google Scholar 45.Saaddine
JBNarayan
KMVinicor
F Vision loss: a public health problem?
Ophthalmology 2003;110253- 254
PubMedGoogle Scholar 46.Schoen
CDoty
MMCollins
SRHolmgren
AL Insured but not protected: how many adults are underinsured?
Health Aff (Millwood) 2005;W5-289- W5-302
PubMeddoi:10.1377/hlthaff.W5.289
Google Scholar 47.Department of Health and Human Services, Healthy People 2010: Understanding and Improving Health. 2nd Washington, DC Dept of Health and Human Services2000;
48.Puent
BDKlein
BEKlein
RCruickshanks
KJNondahl
DM Factors related to vision care in an older adult cohort.
Optom Vis Sci 2005;82612- 616
PubMedGoogle Scholar 49.Orr
PBarron
YSchein
ODRubin
GSWest
SK Eye care utilization by older Americans: the SEE Project: Salisbury Eye Evaluation.
Ophthalmology 1999;106904- 909
PubMedGoogle Scholar 50.Baker
RSBazargan
MBazargan-Hejazi
SCalderon
JL Access to vision care in an urban low-income multiethnic population.
Ophthalmic Epidemiol 2005;121- 12
PubMedGoogle Scholar 51.Nelson
KMChapko
MKReiber
GBoyko
EJ The association between health insurance coverage and diabetes care: data from the 2000 Behavioral Risk Factor Surveillance System.
Health Serv Res 2005;40361- 372
PubMedGoogle Scholar 52.Paz
SHVarma
RKlein
RWu
JAzen
SP Noncompliance with vision care guidelines in Latinos with type 2 diabetes mellitus: the Los Angeles Latino Eye Study.
Ophthalmology 2006;1131372- 1377
PubMedGoogle Scholar 53.Wang
FJavitt
JC Eye care for elderly Americans with diabetes mellitus: failure to meet current guidelines.
Ophthalmology 1996;1031744- 1750
PubMedGoogle Scholar 54.Ross
JSBradley
EHBusch
SH Use of health care services by lower-income and higher-income uninsured adults.
JAMA 2006;2952027- 2036
PubMedGoogle Scholar 55.Bailey
RNIndian
RWZhang
XGeiss
LSDuenas
MRSaaddine
JBCenters for Disease Control and Prevention, Visual impairment and eye care among older adults: five states, 2005.
MMWR Morb Mortal Wkly Rep 2006;551321- 1325
PubMedGoogle Scholar 56.Pollard
TLSimpson
JALamoureux
ELKeeffe
JE Barriers to accessing low vision services.
Ophthalmic Physiol Opt 2003;23321- 327
PubMedGoogle Scholar 57.Maciosek
MVCoffield
ABEdwards
NMFlottemesch
TJGoodman
MJSolberg
LI Priorities among effective clinical preventive services: results of a systematic review and analysis.
Am J Prev Med 2006;3152- 61
PubMedGoogle Scholar 58.Saaddine
JBCadwell
BGregg
EW
et al. Improvements in diabetes processes of care and intermediate outcomes: United States, 1988-2002.
Ann Intern Med 2006;144465- 474
PubMedGoogle Scholar 59.Centers for Disease Control and Prevention, Correctable visual impairment among persons with diabetes: United States, 1999-2004.
MMWR Morb Mortal Wkly Rep 2006;551169- 1172
PubMedGoogle Scholar 60.Aday
LAAndersen
RM Equity of access to medical care: a conceptual and empirical overview.
Med Care 1981;194- 27
PubMedGoogle Scholar 61.Aday
LAAndersen
RM The national profile of access to medical care: where do we stand?
Am J Public Health 1984;741331- 1339
PubMedGoogle Scholar 62.Andersen
RAday
LA Access to medical care in the US: realized and potential.
Med Care 1978;16533- 546
PubMedGoogle Scholar 63.Andersen
RMMcCutcheon
AAday
LAChiu
GYBell
R Exploring dimensions of access to medical care.
Health Serv Res 1983;1849- 74
PubMedGoogle Scholar 64.Andersen
RM Revisiting the behavioral model and access to medical care: does it matter?
J Health Soc Behav 1995;361- 10
PubMedGoogle Scholar