Vision Loss and Blindness

The VEHSS composite estimates of visual acuity loss estimate the prevalence of best corrected visual acuity (BCVA) loss or blindness in the better-seeing eye by combining multiple sources of data available in VEHSS, including self-reported difficulty seeing from the American Community Survey (ACS) and National Survey of Children’s Health (NSCH) and examination-based data on visual acuity loss from the National Health and Nutrition Examination Survey (NHANES) and published population-based examination studies.

VEHSS reports the prevalence of vision loss based on objectively measured best corrected visual acuity (BCVA) in the better-seeing eye from the IRIS Registry and the National Health and Nutrition Examination Survey (NHANES). The IRIS Registry reports visual acuity among patients of participating ophthalmology practices and thus represents vision loss among a sample of ophthalmology patients. NHANES used autorefractors to approximate BCVA among a nationally representative population sample. Results for measured best corrected acuity are reported based on the following 5 subgroups.

VEHSS reports the prevalence of vision loss based on objectively measured presenting visual acuity in the better-seeing eye from NHANES. Presenting acuity was measured among a nationally representative population sample of survey participants wearing whatever eyeglasses or contact lenses they wore to the NHANES examination. Results are available based on the following five subgroups:

VEHSS reports the prevalence of uncorrected refractive error (URE) from NHANES.  NHANES measured presenting visual acuity and autorefractor based best corrected visual acuity among a nationally representative population sample. URE is defined as the examinee having ≤20/50 presenting acuity in the better-seeing eye and improving to >20/40 with autorefractor correction.

VEHSS reports the prevalence of vision loss based on self-report from multiple national surveys, including the American Community Survey (ACS), National Survey of Children’s Health (NSCH), Behavioral Risk Factor Surveillance System (BRFSS), and National Health Interview Survey (NHIS). Self-reported vision loss questions measure perceived vision loss among survey respondents. Self-reported vision loss from surveys can provide large, representative samples that can measure variation by demographic group, risk factors (including social determinants of health), and geography.

Users should use caution when interpreting self-reported vision loss. VEHSS found high levels of variability between different survey questions and between different surveys, even when asking the same question. A validation study conducted by VEHSS found that, among a sample of ophthalmology/optometry patients, the self-reported survey questions included in VEHSS exhibited only marginally acceptable diagnostic accuracy for predicting best corrected visual acuity at the person level. However, in this study, population prevalence based on self-report was highly correlated with prevalence based on best-corrected visual acuity (BCVA) among almost all demographic groups. Although additional research is needed, these findings support the assumption that self-reported measures are correlated with objective measures of visual function. Self-reported vision loss may provide accurate representation of trends and of demographic, risk factor, and geographic disparities in population visual health, although the prevalence rates and counts may differ from those identified through objective measurement.