INTRODUCTION

Heart failure (HF) management requires medication and diet adherence, as well as daily weight and fluid monitoring.1 In addition, patients are often asked to follow specific written instructions after hospital discharge. All of these activities require adequate visual acuity (VA). Yet, to date, little is known about the visual function of adults with HF.

Herein, we provide the first national estimates of the prevalence of visual impairment (VI) among adults with HF.

METHODS

We analyzed data from adults ≥ 50 years of age who underwent VA assessments in the 2005–2008 waves of the National Health and Nutrition Examination Survey (NHANES), a series of ongoing cross-sectional surveys of the civilian, non-institutionalized US population.2 These waves were used because they offer the most recent, objective VA assessments of adults. Since the majority of HF management requires near VA, objective and functional assessments of near vision were studied. All assessments were conducted on each eye, using the individuals’ presenting correction (if any).

Presenting (objective) near visual impairment (PNVI) was defined as seeing worse than 20/40 on a near card. Functional limitations due to vision were assessed using two items from the National Eye Institute’s 25-item Visual Functioning Questionnaire, a previously validated instrument.3 Functional near visual impairment (FNVI) was defined as having at least moderate difficulty with reading ordinary newsprint or doing work that requires seeing close-up. Participants with either PNVI or FNVI were considered to have global near visual impairment (NVI). Finally, self-rated vision was assessed. Like other NHANES studies, participants were classified as having HF if they answered yes to “Has a doctor ever diagnosed you with heart failure?”4, 5

All analyses were weighted to provide national estimates using Stata statistical software (StataCorp LP). We compared differences in participant characteristics, as well as the prevalence of VI, by HF status. All analyses were adjusted for age. The study was approved by the National Center for Health Statistic’s Institutional Review Board and all participants provided written informed consent.

RESULTS

The characteristics of our study sample, weighted to the US population, are displayed in Table 1. Overall, 6.2% (n = 168) of the sample had HF. Participants with HF were older and had more cardiovascular comorbidities those without HF. With respect to ocular comorbidities, diabetic retinopathy and a history of cataract surgery were more prevalent among participants with HF, compared to those without HF. The majority of participants wore glasses for near work (86.5%); however, there was not a statistically significant difference in the use of glasses by HF status.

Table 1 Characteristics of the study population by heart failure status, from the 2005–2008 National Health and Nutrition Examination Survey (NHANES)
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Overall, 23.8% of adults with HF had NVI (Table 2). While the prevalence of PNVI was higher among adults with HF (20.1% [95% CI: 15.2–25.9%]) compared with those without HF (13.2% [11.5–15.1%]), the difference was not statistically significant (p = 0.64). Notably, participants with HF had significantly more FNVI than those without HF (11.05% [CI: 7.6–15.9%] vs. 5.4% [4.6–6.4%], p = 0.002). Finally, the prevalence of self-rated VI was significantly higher among participants with HF (p < 0.001).

Table 2 Prevalence of visual impairment among adults in the USA, by heart failure status from the 2005–2008 National Health and Nutrition Examination Survey (NHANES)
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DISCUSSION

Our study provides the first national prevalence estimates of VI in HF. Objective near VA assessments revealed that one out of five adults with HF has difficulty seeing up close, even when wearing their corrective lenses. Additionally, our findings suggest that HF patients have more functional limitations due to vision compared to those without HF, after accounting for age. While we were unable to assess participants’ ability to perform HF-related tasks, it is likely that difficulty with reading newsprint or doing work up-close would also impose problems with reading medication and nutrition labels,6 as well as HF management handouts and hospital discharge instructions.

One limitation of our study is that HF status in NHANES was ascertained by self-report. Additionally, our estimates likely underestimate the prevalence of VI in HF since nursing home and long-term care residents were not included. Thus, future research is needed to examine VI in HF in a more validated and representative sample.

Nevertheless, given the burden of near and functional VI that exists in this patient population, increased awareness by treating health professionals is warranted. Furthermore, increased collaboration between general internists, ophthalmologists, cardiologists, pharmacists, and caregivers is needed to identify, screen, and potentially treat HF patients who may be at risk.