Recent research published in Scientific Reports estimated there would be an increased prevalence of uncorrected visual impairment in the United States by the year 2050.
Background first, please.
Per the authors of this research, recent projections of uncorrectable visual impairment (20/40 or worse best-corrected visual acuity [BCVA]) haven’t taken into account the increasing prevalence of myopia—specifically in older patients.
To update these projections, investigators sought to more accurately determine the prevalencein the U.S. by taking into consideration the distribution of two factors: age and myopia.
And the goal?
To determine the role of myopia in relation to uncorrectable visual impairment, “including the relative contributions of high myopia (– 6.00 D or worse) and low myopia across the nation.
How’d they do this?
The investigators used the current U.S. census data (an estimated 379 million individuals) to develop a projected age distribution within the United States by 2050.
They then calculated the distribution of myopia (by severity) based on literature-derived prevalence estimates to provide predicted and conservative estimates:
- 58.4% (≤ − 0.50 D, 2050 projection)
- 33.1% (≤ − 1.00 D, 1999–2004 estimate)
To note, calculations were conducted using ages beginning at 35 for the sake of consistency with previous data as well as an age-dependence of visual impairment.
How does age come into play?
The researchers found that the number of projected visually impaired individuals increased exponentially with age for individuals between 40 and 80 years; post-80, however, “mortality exerts a greater influence,” they wrote.
Gotcha. Now talk percentage projections.
For a myopia prevalence of 58.4%, 222 million individuals are expected to be myopic—of which 48 million will have high myopia (− 5.00 D or worse).
For the projected total number of individuals with uncorrected visual impairment (11.4 million), 4.9 million individuals (43%) are expected to have visual impairment that can be directly linked to an eye disease associated with myopia.
And that other original percentage projection?
For a projected myopia prevalence of 33.1%, 8.9 million cases are projected to have uncorrectable visual impairment—of which 4.9 million will be directly linked to myopia.
Meaning …
Based on that data, this means that the number of myopes in the U.S. by 2050 are “over-represented among the visually impaired,” the investigators wrote.
That being said, “76% and 51%, respectively, of the visually impaired (based on the projected 58.4% and 33.1%), are predicted to be the myopic for the two prevalence estimates.”
To note, less than 10% of those visually impaired would be younger than 65 years of age.
Any limitations?
A few were called out, including the availability of limited data regarding the relationship between refractive error and visual impairment.
Further, the model utilized data from the Netherlands, which is noted as a largely non-Hispanic, White population. A more ethnically-diverse population would be needed to improve future estimates for both the U.S. population and other regions.
See more limitations here.
Take away?
The authors concluded that, “between 27 and 43% of uncorrectable visual impairment in the US population in 2050 will be directly attributable to myopia.”
Further, they noted that for every 10% increase in the prevalence of myopia, a million more visual impairment cases would result.
“Thus, efforts to prevent the onset of myopia and slow its progression should have a profound public health benefit,” they wrote.