National Health and Nutrition Examination Survey (NHANES)
National Health and Nutrition Examination Survey (NHANES) is a survey program conducted by CDC's National Center for Health Statistics (NCHS). The objectives of NHANES are to assess the health and nutritional status of adults and children in the United States and to track changes over time. The NHANES combined interviews and physical examinations to sample civilian, noninstitutionalized household population in the United States. The sample size is about 5,000 individuals each year. The NHANES interview contains demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, vision/eye, dental, and physiological measurements, as well as laboratory tests administered by medical personnel.
NHANES and Vision/Eye Disease
The Vision Examination data in NHANES are used to measure the prevalence of visual acuity impairment (visual acuity worse than 20/40) in the U.S. population; measure the distribution of refractive error in the U.S. population; and evaluate functional impairment related to vision.
Health and Nutrition Examination Survey I, NHANES I, 1971–1972. Vision and eye disease component in NHANES I was supported by the National Eye Institute (NEI) and included the measurement of monocular vision with usual correction, slit lamp examination of the lens, and ophthalmoscopy of the retina. Monographs were published in the Rainbow Series and included visual acuity of persons aged 4–74 years. Included within this series are distributions of visual acuity with the usual correction by age, race, sex, geographic region, income, and education. Furthermore, monographs on eye conditions presented by age, race, sex, geographic region, income, and education among persons aged 1–74 years are presented together with the related need for medical care.
National Health and Nutrition Examination Survey III, NHANES III, 1988–1994. Vision and eye disease component in NHANES III included nonmydriatic fundus photographs for one eye among people aged 40 years and older, with no measurement of visual acuity. As a result, the data did not provide national estimates of causes of visual impairment.
National Health and Nutrition Examination Survey IV, NHANES IV, 1999–2002. Since 1999 NHANES has became a continuous annual survey in which 5,000 individuals were examined in each 12-month period. The survey aimed to measure, in the U.S. population aged 12 years and older, the prevalence of visual impairment (VA < 20/40) by cause, measure distribution of refractive error, evaluate screening strategies for visual impairment and eye diseases, and evaluate functional impairment related to vision. The vision examination included 5 parts of measurements: 1) eyeglass prescription for glasses used to view distant objects, 2) presenting visual acuity with current correction, 3) objective refraction, 4) visual acuity incorporating objective refraction, and 5) near vision acuity.
National Health and Nutrition Examination Survey, NHANES 2003–2006. The NHANES 2005–2006 Vision Examination consisted of three parts:
- Eye Glasses Prescription Determination — For persons aged 12 years of age and older, eye glass prescriptions are measured when eye glasses for viewing distant objects are available.
- Distance Visual Acuity and Objective Refraction/Keratometric Evaluation — For all persons aged 12 years and older, distance vision is assessed regardless of whether they wear eye glasses or contacts; the refraction test measures the person’s refractive error and corneal curvature.
- Vision Near Card Test — For persons aged 50 years and older, visual acuity at near was assessed.
NHANES 2005–2006 also included two ophthalmology components: Frequency Doubling Technology (FDT) and Retinal Imaging. The Frequency Doubling Technology (FDT) tests for visual field loss from eye diseases, such as glaucoma, using the Humphrey Matrix Visual Field Instrument. Specifically, the N-30-5 FDT screening protocol was administered to survey participants. It is a 19-point supra-threshold screening test that was administered prior to the Retinal Imaging Exam. The Retinal Imaging Exam tests for the presence of diabetic retinopathy, age-related macular degeneration, and other retinal conditions. Two, 45 degree non-mydriatic digital retinal images of each eye were obtained using an ophthalmic digital imaging system. Both components all test individuals aged 40 years and older.
Vitale S, Cotch MF, Sperduto RD. Prevalence of visual impairment in the United States. JAMA. 2006;295:2158–2163.
Centers for Disease Control and Prevention. Correctable visual impairment among persons with diabetes — United States, 1999–2004. MMWR 2006;55:1169–1172.
Zhang X, Gregg EW, Cheng YJ, Thompson T, Geiss LS, Duenas MR, Saaddine JB. Visual Impairment and Diabetes: NHANES 1999-2004. Arch Ophthalmol 2008;126(10):1421–1427.
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