Purpose:
To estimate the prevalence of myopia in the U.S. using data from a national survey.
Methods:
The National Health and Nutrition Examination Survey (NHANES) is a series of ongoing studies designed to assess the health of adults and children in the U.S., combining interviews and physical examinations. NHANES examines a nationally representative sample of about 5,000 persons each year, identified from households chosen by a complex nation-wide multistage probability sampling design. In 1999-2002, the NHANES examination included objective refraction measurements using a NIDEK ARK-760 autorefractor (Nidek Co, Ltd, Tokyo, Japan) for participants aged 12 years or older. Three measurements were averaged for each eye. We excluded eyes with cataract or refractive surgery. The eye with the largest absolute value of spherical equivalent (SphEq) was used to characterize each participant. Myopia was defined as SphEq ≤-1.0 D. Prevalence estimates were computed using NHANES sampling weights to account for the multistage probability sampling design.
Results:
15,193 persons aged 12 years or older participated in the 1999-2002 NHANES; 14,203 presented to the mobile examination center. Of these, 12,680 had usable refraction data (608 had cataract or refractive surgery in both eyes; 915 had missing data due to lack of time, inability to complete the vision examination, or equipment failure). Individuals with missing data tended to be older and were slightly more likely to be female. The overall age-standardized prevalence of myopia was 32.6% (95% CI, 30.9-34.2%); prevalence varied considerably by age, gender, and ethnicity. Myopia prevalence tended to be lowest in those aged 60 years or older (significantly so for those of Black and those of White ethnicity).The prevalence of high myopia (SphEq ≤-5.0 D) was 6.4% (95% CI, 5.5-7.2%) and was generally higher in females than in males, particularly in the 20-39-year age group (8.8% [95% CI, 7.2-10.4%] versus 5.6% [95% CI, 4.1-7.0%]), although this gender difference varied substantially by ethnicity and age.
Conclusions:
Myopia is common in the U.S., affecting 68 million Americans aged 12 years or older.
Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • myopia