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Abstract
Purpose: To describe the frequency doubling technology (FDT) methodology to measure visual field loss in the National Health and Nutrition Examination Survey and to evaluate data reliability.
Methods: Participants aged 40 years and older were eligible (n = 2,529) for 2 visual field tests per eye performed with the Humphrey Matrix N-30-5 screening test. Visual field loss was determined using a 2-2-1 algorithm requiring 2 complete tests per eye, with at least 2 abnormal field results in each test, and 1 common abnormal field.
Results: Response rate was 86.2%. Time constraints were the main reason for no exam (55.6%). Median times were: single test, 37 seconds; entire exam, 9.1 minutes. When defining reliability based on ≤ 1/3 blind spots, ≤ 1/3 false positive tests, and technician noted proper fixation, 80.1% of examined adults had 2 reliable tests for both eyes; an additional 13.4% had 2 reliable tests for 1 eye. Increasing age, decreasing visual acuity, and the presence of self-reported glaucoma resulted in decreased examination rates, increased test times, and decreased data reliability. Sensitivity and specificity to detect persons with glaucoma was 54.8% and 91.9%, respectively.
Conclusions: FDT is a feasible, fast, and reliable method for visual field loss screening in a population-based U.S. study, with an 86.2% response rate, median exam time ~9 minutes, and nearly 95% of examined participants having complete, reliable results in 1 or both eyes.
Acknowledgments
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.
Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. CAJ received consultant fees from Welch Allyn until 2010. RPR is an employee of Pfizer and owns stock in Pfizer. PPL has received consultant fees/financial support from Alcon Research Institute, Allergan, Genentech, and Pfizer and owns stock in Merck and Pfizer.”