The annual number of new cases of blindness and low vision among people aged 45 years and older is estimated to double during the next 30 years, suggests a study published online November 2 in JAMA Ophthalmology.
The results may help policymakers plan for the future and decide how to allocate resources to help people with loss of vision, an often life-changing issue.
“[A]ssuming the prevalence and mortality rates stay constant, we expect a greater need for services for those patients with [low vision] as the aging population increases over the next several decades,” Tiffany Chan, OD, from Johns Hopkins University School of Medicine, Baltimore, Maryland, and colleagues write.
Most low vision and blindness are related to aging, and both contribute greatly to disability in the United States. Visual impairment can interfere with daily activities and increases the risk for falls and medication mismanagement.
Knowing the incidence, or the number of new cases of low vision each year, is important for policy makers and may be more informative than prevalence, which represents the backlog of people who still need services.
However, the prevalence and incidence of blindness and low vision in the United States have not been estimated for more than a decade.
The researchers used visual acuity measurements taken from 6016 participants in the 2007 to 2008 National Health and Nutrition Examination Survey (NHANES). Because NHANES has data on age, sex, and race/ethnicity, researchers were able to analyze the data by these variables. They also used 2010 census data and constructed rate models to estimate the annual incidence of low vision and blindness for 2017, 2030, and 2050.
The investigators defined low vision as best-corrected visual acuity (BCVA) in the better-seeing eye of less than 20/60 (according to the World Health Organization and Medicare definitions) or less than 20/40 (according to consensus that limitations may occur at this level of acuity). They considered blindness as BCVA 20/200 or less, or legal blindness as defined by the US Social Security Administration.
Results suggested that both prevalence and annual incidence of low vision and legal blindness will roughly double during the next 3 decades among people aged 45 years and older.
In this age group, the estimated prevalence of BCVA less than 20/40 is estimated to increase from 3,894,406 in 2017 to 7,594,797 in 2050. The estimated prevalence of BCVA less than 20/60 is expected to increase from 1,483,703 in 2017 to 2,893,490 in 2050. The prevalence of legal blindness is estimated to increase from 1,082,790 in 2017 to 2,111,637 in 2050.
Likewise, the estimated annual incidence of BCVA less than 20/40 among people aged 45 years and older is expected to jump from 481,970 new cases in 2017 to 1,006,711 in 2050. The annual incidence of BCVA less than 20/60 in this same age group is expected to increase from 183,618 new cases in 2017 to 383,539 in 2050. The number of new cases of legal blindness is expected to increase from 134,002 in 2017 to 279,900 in 2050.
The authors note several limitations that could lead to over- or underestimates of vision loss in the United States. The NHANES data did not include information on visual field testing or from institutionalized individuals, which could have led to an underestimate of vision loss. Researchers used autorefraction to measure visual acuity, which may have been inaccurate in some people and could have overestimated visual acuity loss.
The study was funded by grants from the Reader’s Digest Partners for Sight Foundation and from the National Eye Institute of the National Institutes of Health. Dr Massof reports consulting for Janssen. The other authors have disclosed no relevant financial relationships.
JAMA Ophthalmol. Published online November 2, 2017. Full text
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