Quality of Life Research

, Volume 20, Issue 6, pp 845–852

Visual impairment and health-related quality of life among elderly adults with age-related eye diseases

Authors

    • Division of Adult and Community HealthCenters for Disease Control and Prevention
  • John E. Crews
    • Division of Diabetes TranslationCenters for Disease Control and Prevention
  • Laurie D. Elam-Evans
    • Division of Adult and Community HealthCenters for Disease Control and Prevention
  • Amy Z. Fan
    • Division of Adult and Community HealthCenters for Disease Control and Prevention
  • Xinzhi Zhang
    • Division of Diabetes TranslationCenters for Disease Control and Prevention
  • Amanda F. Elliott
    • Division of Diabetes TranslationCenters for Disease Control and Prevention
  • Lina Balluz
    • Division of Adult and Community HealthCenters for Disease Control and Prevention
Article

DOI: 10.1007/s11136-010-9825-z

Cite this article as:
Li, Y., Crews, J.E., Elam-Evans, L.D. et al. Qual Life Res (2011) 20: 845. doi:10.1007/s11136-010-9825-z

Abstract

Purpose

To examine the association between age-related eye disease (ARED), visual impairment, and health-related quality of life (HRQOL).

Methods

We used data from the 2006 and 2008 Behavioral Risk Factor Surveillance System to examine self-reported visual impairment and two HRQOL domains—physical impairment (including poor general health, physical unhealthy days, activity-limitation days, and disability) and mental distress (including mental unhealthy days, life dissatisfaction, major depression, lifetime depression, and anxiety) for people aged 65 years or older, by ARED status.

Results

People with any ARED were more likely than those without to report visual impairment as well as physical impairment and mental distress. The prevalence of visual impairment (P trend <0.001) and physical impairment (P trend <0.001) increased with increasing number of eye diseases after controlling for all covariates. There was no significant linear trend, however, in mental distress among people with one or more eye diseases.

Conclusion

ARED was found to be associated with visual impairment and poorer HRQOL. Increasing numbers of AREDs were associated with increased levels of visual impairment and physical impairment, but were not associated with levels of mental distress.

Keywords

Age-related eye diseaseHealth-related quality of lifeVisual impairment

Introduction

As the proportion of older adults in the United States grows, visual impairment is becoming an increasingly important public health concern [1, 2]. In the United States, visual disability ranks among the top 10 disabilities [3]. Age-related eye diseases (ARED), including cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy, represent the most common causes of visual impairment [4, 5]. In addition, these AREDs often coexist to exacerbate vision impairment [69] Age-related eye diseases affect quality of life [10, 11] and are major causes of falls [12] and injuries [13]. Persons with systemic disorders such as diabetes are more likely to have multiple eye conditions [14, 15]. While a number of studies have recognized prevalence and effects of co-occurring chronic conditions [16, 17], few population-based studies have examined co-occurring eye diseases among older people.

Health-related quality of life (HRQOL) represents an individual’s or group’s perceived physical or mental status [18, 19], and its association with visual impairment and eye diseases has been previously examined [11, 20, 21]. A considerable amount of research regarding quality of life and vision has focused on reports of visual impairment or a single eye disease. The Centers for Disease Control and Prevention (CDC) has developed a set of questions called the “Healthy days measures,” to measure HRQOL and includes questions related to general health, physical unhealthy days, mental unhealthy days, and activity-limitation days. The “Healthy days measures” been shown to be reliable [22, 23] and have been used to assess the burden of chronic diseases [23, 24]. Moreover, the “Healthy days measures” have been shown to predict morbidity, health care use, and mortality and are associated with disability, risky health behaviors, and sociodemographic factors [18]. This instrument, however, has not been used to assess HRQOL among people with ARED.

In the present study, we examined the association between the number of AREDs an individual has and HRQOL. To further explore how ARED is associated with different domains of HRQOL (i.e., physical and mental health), we included variables such as life satisfaction and disability in addition to the “Healthy days measures”.

Methods

Data source

The Behavioral Risk Factor Surveillance System (BRFSS) provides state specific data on adults aged 18 years and older in the United States (including the District of Columbia [DC], Guam, Puerto Rico, and the Virgin Islands). It gathers data on preventive health practices and risk behaviors that are linked to chronic diseases, injuries, and preventable infectious diseases among non-institutionalized US adults. Each year, in addition to the survey’s core section, which includes the “Healthy days measures”, states may add optional modules with detailed health questions addressing topical health concerns including such matters as diabetes and mental health. The Vision and Access to Eye Care module (Vision module) collects information regarding visual impairment, access to eye care, and self-reported diagnoses of AREDs (macular degeneration, glaucoma, and cataracts) among respondents aged 40 years and older. Self-reported diagnosis of diabetic retinopathy is obtained from the Diabetes Module. In 2006 and 2008, seventeen states administered both Vision and Diabetes module; four of whom administered the modules in both years. Nine states also administered the Depression and Anxiety module. The response rate (the percentage of complete and partial interviews among all the households in the sample) ranged from 39.8 to 66.0% across states. The cooperation rate (the percentage of complete interviews among the households actually contacted) ranged from 67.7 to 81.8% across states.

Measures

Health-related quality of life measures

“Healthy days measures” include four questions: general health (“Would you say that in general your health is excellent, very good, good, fair, or poor?”), physical unhealthy days (“Now thinking about your physical illness and injury, for how many days during the past 30 days was your physical health not good?”), mental unhealthy days (“Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?”), and activity-limitation days (“During the past 30 days, for about how many days did poor physical or mental health keep you from doing your usual activities, such as self-care, work, or recreation?”). The response of “fair” or “poor” to the general health question was defined as “poor general health”. Healthy days variables were each dichotomized into 14 or more days versus 13 or fewer days in the analysis.

In addition to the “Healthy days measures” we also included questions about life satisfaction and disability. The response of “dissatisfied” and “very dissatisfied” to the question, “In general, how satisfied are you with your life?” was defined as life dissatisfaction. The response of “yes” to the question, “Are you limited in any way in any activities because of physical, mental, or emotional problems?” or “Do you now have any health problem that requires you to use special equipment, such as a cane, a wheelchair, a special bed, or a special telephone?” was defined as having disability.

Of the 17 states implementing the vision module, only 9 states also used the depression and anxiety module during the study years. Eight questions, adopted from the Patient Health Questionnaire-8 [25], were asked regarding the number of days in the previous 2 weeks the respondent had experienced a particular depressive symptom (having little interest in doing things, feeling down or depressed or hopeless, having trouble with sleeping, feeling tired or having little energy, having poor appetite, feeling bad about self, having trouble concentrating on things, and being fidgety or restless). Major depression was defined as having at least 2 of 8 symptoms, 1 of which must be depressed mood or loss of interest or pleasure, for ≥7 days in the past 2 weeks [25]. Lifetime depression and anxiety were based on self-reported diagnosis by health professionals.

For the purpose of conceptual clarity, we refer to two domains of HRQOL in the analyses and throughout the paper. Previous research [12, 13] demonstrated that the “Healthy days measures” can be classified into physical and mental domains. We term our domains physical impairment and mental distress. The physical impairment domain is comprised of the study variables: general health, physical unhealthy, and activity limitation from the “Healthy days measure” as well as the disability variable. The mental distress domain is comprised of the study variable mental unhealthy (from the “Healthy days measure”), the life satisfaction measure, and major depression, lifetime depression, and lifetime anxiety (from the depression and anxiety module).

Eye disease and vision measure

AREDs were identified by respondents who indicated in the affirmative that they “had been told by an eye doctor or other health care professional,” that they had cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy. Four groups were examined: those with no eye disease, those with any one disease, those with any two diseases, and those with any three or more eye diseases.

Visual impairment was assessed using the following questions regarding distance and near visual impairment, respectively: “How much difficulty, if any, do you have in recognizing a friend across the street?” and “How much difficulty, if any, do you have reading print in newspapers, magazines, receipts, menus, or numbers on the telephone?” If the respondents wore glasses or contact lenses, they were to respond about their vision when they have glasses or contact lenses on. The response of “a little difficulty”, “moderate difficulty”, and “extreme difficulty” to either question served as the case definition of visual impairment for distance visual impairment alone and near visual impairment alone. A combined “distance and near visual impairment” was classified when the respondent had positive responses to both distance and near visual impairment.

Covariates included respondents’ demographic and socioeconomic characteristics (age [continuous], sex [male and female], race/ethnicity [White, Black, Hispanic, and other], education [<high school, =high school, and >more than high school], and income [<$25,000, 25,000–50,000, and >&50,000]), and other chronic conditions (coronary heart disease, stroke, and diabetes).

Statistical analysis

Statistical analyses were performed using SAS (version 9.1, SAS Institute Inc.) and SUDAAN (version 9.0) to account for the complex sampling design of BRFSS. We restricted analysis to respondents aged 65 years and older. Since some states used the module for 2 years and others for only 1 year, we created and applied a half weight to the states where the Vision Module was administered for both study years. This technique prevents overrepresentation of respondents in the states using the Vision Module for 2 years.

Initially, we had 40,679 participants in the sample. After excluding the respondents with missing values on eye disease, the sample size declined to 36,348. The questions about major depression, lifetime depression, and anxiety were asked in the Depression and Anxiety Module. This module was only conducted in 9 states of 17 using the Vision module. Therefore, all the comparisons and multivariate analysis of these three variables were based on a 9 state sample (N = 24,188).

Wald Chi-square test was used to compare differences in general characteristics, visual impairment and quality of life among people with and without eye disease(s). We used a series of logistic regression analyses to assess the association. The dependent variables were near visual impairment, distance visual impairment, near & distance visual impairment combined, poor/fair general health, physical unhealthy, disability, activity limitation, life dissatisfaction, mental unhealthy, depression, and anxiety in each logistic regression analysis. All dependent variables were dichotomized. The independent variables were the number of ARED, age, sex, race/ethnicity, education, income, diabetes, heart disease, and stroke in each logistic regression analysis. Adjusted odds ratio and 95% confidence interval (CI) from logistic regression were used to examine the association of having above-mentioned health outcomes with the presence of any ARED. Predictive marginal (PM) and 95% CI from logistic regression models were used to compare the “adjusted predicted probability” of having the above-mentioned health outcome by number of ARED among people with ARED after adjustment for potential confounders.

Results

Among the 17 states administering the Vision Module in 2006 and 2008, 36,348 respondents aged 65 years and older completed the survey. Of those, 13,866 (38.2%) reported having no ARED; 17,114 (47.1%) reported having any 1 ARED; 4,603 (12.7%) reported having any 2 AREDs, and 765 (2.1%) reported having 3 or more AREDs. Sample size varied slightly due to missing values for different HRQOL measures.

Among people reporting any one of ARED, cataract was the most prevalent disease (90.1%). Among people reporting any two AREDs, cataract and glaucoma was the most common combination (42.4%) followed by cataract and macular degeneration (41.2%).

Characteristics of the study population by the presence of ARED are described in Table 1. People reporting any ARED were more likely to be older, woman, and white and have lower education and lower income levels compared to those with no ARED. Compared to people without AREDs, people with AREDs had a higher prevalence of visual impairment, physical impairment (poor general health, higher prevalence of disability, higher prevalence of reporting of physical unhealthy days, and activity-limitation days) and mental distress (higher prevalence of reporting of mental unhealthy days, life dissatisfaction, major depression, lifetime depression, and anxiety) (Table 1).
Table 1

Characteristics of the study population (adults ≥65 years) by the presence of any age-related eye diseases, selected states, behavioral risk factor surveillance system, 2006 & 2008

 

No eye disease

Na = 13,866

Any eye disease

Na = 22,482

P valuec

% (SE)b

% (SE)

Mean age (SE)d

72.3 (0.1)

75.8 (0.1)

<0.001

Sex

  

<0.001

 Male

48.6 (0.7)

37.7 (0.6)

 

 Female

51.4 (0.7)

62.3 (0.6)

 

Race/ethnicity

  

0.005

 White

81.2 (0.6)

83.7 (0.5)

 

 Black

7.9 (0.4)

6.8 (0.3)

 

 Hispanic

6.6 (0.4)

5.3 (0.3)

 

 Others

4.3 (0.3)

4.2 (0.3)

 

Education

  

0.004

 <High school

14.1 (0.5)

16.2 (0.4)

 

 High school

34.6 (0.7)

34.9 (0.5)

 

 >High school

50.8 (0.7)

48.7 (0.6)

 

Income (annual household)

  

<0.001

 <25,000

27.5 (0.6)

33.0 (0.5)

 

 25,000–50,000

25.5 (0.6)

25.3 (0.5)

 

 >50,000

25.6 (0.6)

18.4 (0.5)

 

Heart disease

16.6 (0.5)

23.6 (0.5)

<0.001

Stroke

6.1 (0.3)

9.9 (0.3)

<0.001

Diabetes

14.0 (0.5)

21.5 (0.5)

<0.001

Visual impairment

   

 Near visual difficulty alonee

23.8 (0.6)

32.3 (0.5)

<0.001

 Distance visual difficulty alone

9.6 (0.4)

18.8 (0.4)

<0.001

 Near & distance visual difficulty combined

5.3 (0.3)

12.8 (0.4)

<0.001

Physical impairment

   

 Poor/fair general health

22.8 (0.6)

31.8 (0.5)

<0.001

 Disabilityf

28.9 (0.6)

42.5 (0.6)

<0.001

 Physical unhealthyg

14.5 (0.5)

20.2 (0.5)

<0.001

 Activity limitationg

7.1 (0.3)

10.5 (0.4)

<0.001

Mental distress

   

 Life dissatisfaction

2.7 (0.1)

3.8 (0.2)

<0.001

 Mental unhealthyg

5.4 (0.3)

6.9 (0.3)

0.007

 Major depressionh

3.0 (0.4)

4.7 (0.4)

0.002

 Lifetime depressionh

6.1 (0.3)

8.7 (0.4)

<0.001

 Lifetime anxietyh

4.3 (0.3)

6.5 (0.4)

<0.001

Age-related eye diseases include cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy

AL, AZ, CO, CT, FL, GA, IN, KS, MO, NE, NM, NC, NY, OH, TN, TX, and WY

aSample size varied slightly due to missing values for different HRQOL measures: The missing values were: distance visual difficulty = 294, near visual difficulty = 264, distance and near visual difficulty = 66, general health = 299, physical unhealthy days = 1427, activity limitation = 660, disability = 9, life dissatisfaction = 359, mental unhealthy days = 901

bStandard error

cWald Chi-square test was used to compare differences

dMean and standard error

eThe responses ‘a little difficulty’, ‘moderate difficulty’, and ‘extremely difficulty’ to the question, “How much difficulty, if any, do you have in recognizing a friend across the street?” or “How much difficulty, if any, do you have reading print in newspapers, magazines, receipts, menus, or numbers on the telephone?” were defined as difficulty

fThe response, “Yes,” to the question, “Are you limited in any way in any activities because of physical, mental, or emotional problems?” or “Do you now have any health problem that requires you to use special equipment, such as a cane, a wheelchair, a special bed, or a special telephone”, was defined as disability

gDichotomized into 14 or more days vs. 13 or fewer days

hData only available for nine states N = 24,188

Compared to people without AREDs, people with AREDs had a significant higher likelihood of visual impairment, physical impairment (poor/fair general health, disability, physical unhealthy, and activity limitation), and mental distress (mental unhealthy, life dissatisfaction, major depression, lifetime depression, and anxiety). After adjustment of demographic variables and other chronic conditions, all the results remained significant. Compared to people reporting no ARED, those with one or more AREDs were more likely to report having near visual impairment (adjusted odds ratio (AOR) = 1.45, 95% CI = 1.33–1.57) and distance visual impairment (AOR = 2.03, 95% CI = 1.81–2.27). They were also more likely to report having poor general health (AOR = 1.32, 95% CI = 1.20–1.46), disability (AOR = 1.57, 95% CI = 1.47–1.67), life dissatisfaction (AOR = 1.31, 95% CI = 1.09–1.58), and had a higher probability of being physical unhealthy, mental unhealthy, and activity imitated. AORs for depression and anxiety, although based on respondents from 9 states, were also significantly higher in people with AREDs than those without the condition (Table 2).
Table 2

Logistic regression models for any age-related eye diseases in association with visual impairment, physical impairment and mental distress, selected states, behavioral risk factor surveillance system, 2006 & 2008

 

Any eye diseasea

ORb (95% CI)

AORc (95% CI)

Visual impairment

Near visual difficulty alone

1.55 (1.43–1.68)

1.45 (1.33–1.57)

Distance visual difficulty alone

2.24 (2.02–2.49)

2.03 (1.81–2.27)

Near & distance visual difficulty combined

2.69 (2.34–3.09)

2.36 (2.05–2.72)

Physical impairment

Poor/fair general health

1.58 (1.45–1.72)

1.32 (1.20–1.46)

Physical unhealthy

1.56 (1.41–1.73)

1.28 (1.15–1.43)

Disability

1.83 (1.69–1.98)

1.57 (1.47–1.67)

Activity limitation

1.54 (1.34–1.77)

1.26 (1.13–1.40)

Mental distress

Life dissatisfaction

1.46 (1.23–1.73)

1.31 (1.09–1.58)

Mental unhealthy

1.47 (1.28–1.69)

1.40 (1.27–1.54)

Major depression

1.59 (1.18–2.13)

1.39 (1.17–1.64)

Lifetime depression

1.37 (1.15–1.64)

1.25 (1.11–1.40)

Lifetime anxiety

1.49 (1.22–1.82)

1.31 (1.15–1.49)

A series of logistic regression models (12) with each indicator of visual impairment (Near visual impairment, Distance visual impairment, Near & distance visual impairment combined), physical impairment (Poor/fair general health, Physical unhealthy, Disability, Activity limitation), and mental distress (Life dissatisfaction, Mental unhealthy, Major depression, Lifetime depression, Lifetime anxiety) as dichotomized outcomes, number of ARED as predictor

aPersons without age-related eye disease are used as the reference group

bCrude odds ratio

cAdjusted odds ratios were obtained after adjustment for age, sex, race/ethnicity, education, income, diabetes, heart disease, and stroke, P < 0.05

Predictive marginal (PM) from logistic regression, defined as “adjusted predicted probability”, is to produce standardized estimates for different subgroups when taking potential confounders into account [26]. Originally, we treated “Healthy days measures” as continuous dependant variables in linear regression model and calculated least square means. We then dichotomized these health outcome variables and carried out logistic regressions to compare the PM of having certain health outcome across groups with different numbers of ARED (Table 3). These two approaches yielded similar results. The PM for visual impairment (near visual impairment alone, distance visual impairment alone, and distance and near visual impairment combined) and physical impairment (poor general health, disability, physical unhealthy, and activity limitation) corresponded with increasing numbers of AREDs in a linear dependent manner. By contrast, the linear trend for mental distress (life dissatisfaction, mental unhealthy, major depression, lifetime depression, and lifetime anxiety) was not significant though. (Table 3).
Table 3

Logistic regression models for the number of age-related eye diseases in association with visual impairment, physical impairment and mental distress, selected states, behavioral risk factor surveillance system, 2006 & 2008

 

Any 1 eye disease

P.M.a (SE)

Any 2 eye diseases

P.M. (SE)

3 or more eye diseases

P.M. (SE)

P for Linear Trend

Visual impairment

Near visual difficulty alone

29.6% (0.6%)

44.2% (1.2%)

57.2% (2.9%)

<0.001

Distance visual difficulty alone

16.4% (0.5%)

29.8% (1.1%)

40.1% (2.8%)

<0.001

Near & distance visual difficulty combined

9.9% (0.4%)

21.6% (1.0%)

31.7% (2.9%)

<0.001

Physical impairment

Poor/fair general health

31.9% (0.6%)

35.7% (1.0%)

37.8% (2.3%)

<0.001

Physical unhealthy

19.7% (0.5%)

22.0% (1.0%)

23.6% (2.3%)

0.03

Disability

40.9% (0.6%)

48.3% (1.2%)

56.4% (3.2%)

<0.001

Activity limitation

9.8% (0.4%)

12.3% (0.8%)

12.9% (1.8%)

0.02

Mental distress

Life dissatisfaction

4.8% (0.3%)

5.2% (0.5%)

5.6% (1.1%)

0.67

Mental unhealthy

6.7% (0.3%)

8.2% (0.7%)

8.5% (1.8%)

0.35

Major depression

4.2% (0.4%)

6.1% (0.9%)

7.4% (2.4%)

0.08

Lifetime depression

11.0% (0.6%)

11.9% (1.2%)

14.3% (3.1%)

0.4

Lifetime anxiety

8.2% (0.6%)

8.6% (1.1%)

14.0% (3.0%)

0.07

A series of logistic regression models (12) with each indicator of visual impairment (Near visual impairment, Distance visual impairment, Near & distance visual impairment combined), physical impairment (Poor/fair general health, Physical unhealthy, Disability, Activity limitation), and mental distress (Life dissatisfaction, Mental unhealthy, Major depression, Lifetime depression, Lifetime anxiety) as dichotomized outcomes, number of ARED as predictor

aPM (SE) = Predictive marginal (Standard error)

Predictive marginals were obtained after adjustment for age, sex, race/ethnicity, education, income, diabetes, heart disease, and stroke. P < 0.05

Discussion

Several studies have examined the relationship between different eye diseases and quality of life [10, 11, 2729]. Although Broman et al. [11] suggested that decrements in quality of life associated with multiple eye diseases were beyond the additive decrements associated with each individual one, comorbidity was not the focus of their study. In our multi-state, population-based sample of US adults aged 65 and older, having any ARED was associated with considerable reduction in HRQOL and increased visual impairment compared to those with no eye disease. In addition, comorbid AREDs were associated with increased visual impairment and physical impairment. Even though having any eye disease was associated with mental distress, the relationship did not show a dose–response pattern when additional eye diseases were reported.

The phenomenon that visual and physical impairment became worse with the increasing numbers of AREDs merits further discussion. First, it is reasonable to infer that visual impairment became worse with the increasing number of eye diseases. For example, glaucoma, which results in a field restriction, combined with macular denegation, which results in a central field restriction, may effectively eliminate usable vision. Second, multiple AREDs may suggest a longer duration of having eye disease. Klein’s study [9] demonstrated early age-related macular degeneration, central cataract, and glaucoma had a small effect on visual acuity while late stages of irreversible eye diseases were the main cause of legal blindness. Chia’s research indicated that severity of visual impairment was directly related to declines in HRQOL [30]. Multiple AREDs, especially if representing late stage eye disease and greater severity of visual impairment, may lead to substantial limitations in mobility and physical function. Third, people with multiple eye conditions were more likely to have other systemic chronic conditions or vice versa. Among diabetic patients, hyperglycemia may lead to cataract, diabetic retinopathy, and neurovascular glaucoma simultaneously [15]. Systemic disorders have also been associated with a lower level of HRQOL [24, 31, 32].

By contrast, the number of AREDs did not show a dose–response relationship with mental health. Our findings are consistent with Esteban’s [33] and Tay’s [34] reports that declining vision generally had no significant impact on mental health, and the declines in mental health did not vary significantly with the severity of visual impairment. A study on multimorbidity of systemic diseases in the elderly reported similar patterns where physical domains of HRQOL decreased with increased morbidity, but psychological domains did not [35]. In the present sample, people with multiple AREDs were more likely to be older. Older people may consider physical and visual disability as a normal part of aging. Compared to other chronic conditions, multiple eye conditions may play a less important role affecting mental health. In our study, differences in all mental subscales were not significant after taking other chronic diseases into account. Additionally, people with multiple eye conditions may have a longer disease duration than people with a single eye disease. This may allow them to adapt and adjust to declines in vision. Other studies, however, have found that the severity of visual impairment is associated with a significant decrease in mental health scores [10, 11, 36]. The influence of comorbidity on the psychological dimensions of HRQOL is less certain than its influence on the physical domains [37].

General health and life satisfaction are overall ratings and may relate to both the physical and mental dimensions of HRQOL. In Jiang’s study [38], however, respondents reporting poorer general health were more likely to be physically unhealthy than mentally unhealthy. Life satisfaction, on the other hand, has already been viewed as a dimension of mental health [39, 40]. It has high correlation with depressive symptoms, self-esteem, anxiety, psychosomatic symptom, and other diagnosed mental diseases, all of which are aspects of mental health [4143]. While some studies suggest that generic questions are not as sensitive to changes in visual capacity, as are vision-specific questions [44] and are rarely used to assess the association between eye conditions and quality of life [19], our study showed these general measurements are consistent with other indicators in their domain. Disability is not treated as a HRQOL measure traditionally. However, disability reflects physical function to some extent. People reporting disability may also report lower quality of life. Thus, it is not surprising that disability mirrors other measures in the domain of physical impairment in the present study.

This study is subject to several limitations. First, this is a cross-sectional design, and therefore, we are not able to infer causality. Second, these are self-reported data and may not be as accurate as clinical measurement. Self-reported measures, however, have been shown to be a useful and valid method to assess visual function [45] and quality of life [22]. Third, we only included 17 states (9 states for anxiety and depression measures) due to the data availability; these states may not be representative of the United States as a whole or of states that were not included. Additionally, our analysis was restricted to adults aged 65 years and older and may not be generalizable to younger adults. Lastly, among the numerous studies assessing the HRQOL of visually impaired people, the National Eye Institute-Visual Function Questionnaire (VFQ-25) [44] and Medical Outcome Study-36 Item Short Form Health Survey (SF-36) [46] were found to be most often used. Compared with disease-specific quality of life measures, the HRQOL measures utilized in this study are more generic and global.

In conclusion, our study demonstrated the association between AREDs and visual impairment and multiple measures of HRQOL. These findings provide evidence for public health to address the needs of adults aged 65 years and older with multiple age-related eye conditions.

Copyright information

© Springer Science+Business Media B.V. 2010