Though all subject cohorts showed a substantial rise in myopia and high myopia in this study, notable variation was found by sex and ethnicity. Photo: Getty Images. Click image to enlarge.

The National Health and Nutrition Examination Surveys study was the only US population–based, multi-decade study prior to 2000 that tracked steadily increasing myopia prevalence, until now. To understand what’s behind this and suggest prevention strategies, researchers recently investigated the prevalence of myopia and high myopia in Olmsted County, MN—seat of the Rochester metro area and home to the Mayo Clinic—from 1966 to 2019. They found it increased dramatically in both males and females in all age groups during that time, with white and Asian citizens having the highest prevalence and Black populations the lowest. The authors are on staff at the Mayo Clinic Dept. of Ophthalmology.

A total of 81,706 individuals were included. Manifest refractions or lens prescription were converted to spherical equivalent (SE) to estimate prevalence of adult myopia and high myopia. SE ≤-0.5D were considered myopic, while ≤-6D were considered high myopia.

Myopia prevalence increased from 33.9% in 1960s to 57.1% in 2010s. High myopia prevalence increased from 2.8% in 1960s to 8.3% in 2010s. Both males (32% to 55.1%) and females (40.6% to 58.5%) experienced increasing myopia prevalence from the 1960s to 2010s while males (2.6% to 7.4%) and females (3.4% to 9.1%) also had higher high myopia prevalence rates from 1960s through 2010s. Increasing myopia and high myopia prevalence was detected by decade in nearly all age groups (excluding 18 to 24-year-old high myopia participants). White and Asian individuals had the highest myopia prevalence while Black residents had the lowest. The 2000s through the 2010s saw significant increases in myopia prevalence within the White (53.3% to 57%) and Black (41% to 47%) populations.

Black residents had a lower myopia prevalence compared to their white counterparts (41% vs. 53%, respectively) in the 2000s. This is similar to the NHANES data (34% vs. 43%, respectively), and the trend has been documented in other populations. In Olmsted County, the prevalence of myopia/high myopia (2010s) in Asian citizens was 68% and 16%, respectively, both lower than East Asian studies also performed in the 2010s, the authors noted.

As in many regions of the country and wider world, socioeconomic factors in Olmsted County changed from 1966 to 2019, which may also explain the increasing myopia trend. This includes an increase in education demands, a shift from an agrarian/industrial economy to a technical (computer science industry) and healthcare, service-based economy, the authors noted.

The researchers found significant differences in female vs. male citizens during the 2000s and 2010s decades. “While this may represent statistical variation, societal changes in educational and professional-related visual demands between the 1960s and 2000s may also influence sex-dependent myopia,” the authors wrote in their paper on the work for American Journal of Ophthalmology. “A societal trend that shifted the balance during the 1980s from male to majority female college-educated adults has developed. This trend coincides with increasing female myopia prevalence in Olmsted County during the past two decades.”

In conclusion, estimated myopia rates in Olmsted County were higher than those previously predicted in other North American studies and raises concern for the epidemic progressing in the US, the authors explained. “Furthermore, since the rate of myopia appears to be increasing faster than anticipated, more urgent prevention strategies are needed, particularly in younger individuals,” they wrote. Some of these therapies can include increased time outdoors, optical devices, low-dose atropine and possibly orthokeratology.

“We also need to consider the increasing socioeconomic costs associated with both the refractive management demands as well as the healthcare costs, especially associated with high myopia,” the researchers elaborated. “Healthcare policy decisions directed toward prevention seem logical, rationale and we speculate that these would be highly cost-effective. Policy delays would lead to progressive acceleration of myopia. A proactive and organized strategy is critical for developing effective local, regional and national strategies to reduce myopia in the US.”