The Benefits of Screening and Time Outdoors for Pediatric Vision Health

While I am not a fan of several of the current universally recommended screening tests,¹ I am a fan of vision screening. Good screening tests have evidence of direct benefit to patients with minimal harms, and, as Rao et al. point out in Pediatric Vision Screening in this month’s Pediatrics in Review, vision screening has the distinction of having a grade B recommendation from the United States Preventive Service Task Force (USPSTF).² The USPSTF summarizes the benefits as follows: “The USPSTF found adequate evidence that treatment of amblyopia or its risk factors in children aged 3–5 years leads to improved visual acuity.”² This benefit continues for the child’s life, and the harms of screening were found to be low.

Digging deeper into the USPSTF statement was eye opening, so to speak. While it is universally accepted that that the development of amblyopia can be prevented by addressing its risk factors, the USPSTF was unable to conclude (based on evidence available prior to 2017) that vision screening in young children resulted in a reduction of amblyopia. I did not see that coming, and their finding may be attributable to quality of the evidence. After learning this, I searched for newer studies that address this evidence gap and did find two with positive findings.^3,4 Whether the benefit found in these studies translates to the large-scale screening of children attending well visits in the US is an open question.   

The In Brief piece by Rao et al. comes at a time when a marked and alarming increase in the prevalence of myopia worldwide has been noted.^5,6 Studies undertaken to understand this phenomenon have found significant geographic differences in the prevalence of childhood myopia, with rates in teenagers ranging from 73% in South Korea to 10% in Brazil.⁵ An increased prevalence of myopia in childhood is associated with living in an urban environment, high family income, a parental history of myopia, and higher educational attainment. Modifiable factors associated with an increased prevalence of myopia include the total daily amount of time spent doing “near work,” defined as time spent indoors reading, writing, doing homework, and screen time.⁷ Strong evidence supports an association of outdoor time with lower rates of myopia,^6,8 and a Cochrane Library systematic review of randomized controlled trials of the effects of increased outdoor time on myopia concluded “that long-term interventions to increase the time spent outdoors may potentially reduce the development of myopia in children.”⁹ Interestingly, both animal and human studies support the hypothesis that the risk associated with near work time and the protection associated with outdoor time may be moderated by the markedly different degrees of light intensity reaching the retina in these two activities.^8,10 

What can we tell parents? Kids benefit from vision screening and from outdoor time in multiple ways, one of which may be the prevention of nearsightedness . . . but don’t forget the sunglasses.

 References

1. Belamarich PF. Counterpoint: The evidence does not support universal screening and treatment in children. J Clin Lipidol. 2015;9(5 Suppl):S101–S106. doi:10.1016/j.jacl.2015.07.001
2. US Preventive Services Task Force, Grossman DC, Curry SJ, et al. Visions in children aged 6 months to 5 years: US Preventive Services Task Force recommendation statement. JAMA. 2017;318(9):836–844. doi:10.1001/jama.2017.11260
3. Eibschitz-Tsimhoni M, Friedman T, Naor J, Eibschitz N, Friedman Z. Early screening for amblyogenic risk factors lowers the prevalence and severity of amblyopia. J AAPOS. 2000;4(4):194–9. doi: 10.1067/mpa.2000.105274
4. Teed RG, Bui CM, Morrison DG, Estes RL, Donahue SP. Amblyopia therapy in children identified by photoscreening. Ophthalmology. 2010;117(1):159–62. doi: 10.1016/j.ophtha.2009.06.041
5. Liang J, Pu Y, Chen J, et al. Global prevalence, trend and projection of myopia in children and adolescents from 1990 to 2050: a comprehensive systematic review and meta-analysis. Br J Ophthalmol. Published online September 24, 2024. doi:10.1136/bjo-2024-325427
6. Dolgin E. The myopia boom. Nature. 2015;519(7543):276–278. doi:10.1038/519276a
7. Lanca C, Yam JC, Jiang WJ, et al. Near work, screen time, outdoor time and myopia in schoolchildren in the Sunflower Myopia AEEC Consortium. Acta Ophthalmol. 2022;100(3):302–311. doi:10.1111/aos.14942
8. Lingham G, Mackey DA, Lucas R, Yazar S. How does spending time outdoors protect against myopia? A review. Br J Ophthalmol. 2020;104(5):593-599. doi:10.1136/bjophthalmol-2019-314675Ki
9. Kido A, Miyake M, Watanabe N. Interventions to increase time spent outdoors for preventing incidence and progression of myopia in children. Cochrane Database Syst Rev. 2024;6(6):CD013549. Published 2024 Jun 12. doi:10.1002/14651858.CD013549.pub2
10. Zheng L, Liao Z, Zou J. Animal modeling for myopia. Adv Ophthalmol Pract Res. 2024;4(4):173-181. Published 2024 Jun 5. doi:10.1016/j.aopr.2024.06.001