Refractive error, in particular myopia, remains a leading cause of visual impairment worldwide. But do we really understand the risk factors? What is driving the growth of myopia?
Genetic predisposition, lifestyle changes resulting in a combination of decreased time for outdoor activities and increased near work, and reduced light levels and exposure to daytime light have all been attributed. Using both the National Health and Nutrition Examination Survey (NHANES) and the Intelligent Research in Sight (IRIS) Registry, developed by the American Academy of Ophthalmology, the burden of myopia has been elucidated by identifying those at greatest risk for vision loss. An additional analysis of this registry revealed risk factors from a longitudinal study of more than 600,000 U.S. patients aged 35 years or younger.
The risks factors identified were:
- living in the eastern region of the United States;
- refractive error present at an early age; and
- seeing providers in high-income communities.
As you can tell, the data, while interesting, have lots of confounders. For example, seeing a provider in a higher-income community does not mean that high income causes myopia. Rather, it is likely that those at risk are being screened more readily than lower-income communities. And the link between Hispanic ethnicity and myopia was first reported in this study, so more effort is needed to further validate these findings.
While we are learning more about myopia, many unanswered questions still plague our field. With the advent of these larger data studies, more presentations are likely to be elucidated.
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Disclosure: Singh reports he is a consultant to Zeiss, Novartis, Regeneron, Genentech and Alcon and receives grant support from Apellis and Graybug.