Abstract
PurposeAutorefractors allow non-specialists to quickly assess refractive error, and thus could be a useful component of large-scale vision screening programs. In order to better characterize the role of autorefraction for public health outreach programs in resource-limited settings, the diagnostic accuracy of two autorefractors was assessed relative to subjective refraction in an adult Indian population.MethodsAn optometrist refracted a series of patients aged ≥50 years at an eye clinic in Bangalore, India using the Nidek ARK-900 autorefractor first, followed by the 3nethra Royal autorefractor, and then subjective refraction. The diagnostic accuracy of each autorefractor for myopia, hyperopia, and astigmatism was assessed using subjective refraction as the reference standard, and measures of agreement between refractions were calculated.ResultsA total of 197 eyes in 104 individuals (mean age 63 ± 8 years, 52% female) were evaluated. Both autorefractors produced spherical equivalent estimates that were on average more hyperopic than subjective refraction, with a measurement bias of +0.16 D (95%CI +0.09 to +0.23D) for Nidek and +0.42 D (95%CI +0.28 to +0.54D) for 3nethra. When comparing pairs of measurements from autorefraction and subjective refraction, the limits of agreement were approximately ±1D for the Nidek autorefractor and ±1.75D for the 3Nethra autorefractor. The sensitivity and specificity of detecting ≥1 diopter of myopia were 94.6% (95%CI 86.8–100%) and 92.5% (95%CI 88.9–97.5%) for the Nidek, and 89.2% (95%CI 66.7–97.4) and 77.5% (95%CI 71.2–99.4%) for the 3Nethra. The accuracy of each autorefractor increased at greater levels of refractive error.ConclusionsThe sensitivity and specificity of the Nidek autorefractor for diagnosing refractive error among adults ≥50 years in an urban Indian clinic was sufficient for screening for visually significant refractive errors, although the relatively wide limits of agreement suggest that subjective refinement of the eyeglasses prescription would still be necessary.
Highlights
Uncorrected refractive error is the leading cause of visual impairment worldwide, with the greatest burden of disease in low and middle-income countries [1]
When comparing pairs of measurements from autorefraction and subjective refraction, the limits of agreement were approximately ±1D for the Nidek autorefractor and ±1.75D for the 3Nethra autorefractor
The accuracy of each autorefractor increased at greater levels of refractive error
Summary
Uncorrected refractive error is the leading cause of visual impairment worldwide, with the greatest burden of disease in low and middle-income countries [1]. Many eye hospitals in lowresource settings conduct community-based outreach activities largely focused on detection of cataract and refractive error [1]. Such outreach programs often deploy trained refractionists to the community, where they perform subjective refraction with trial lenses. This strategy requires a sufficient supply of refractionists, making it unrealistic in many low-resource settings. An alternative strategy could employ autorefraction, which requires far less training, and would greatly increase the availability of refractive error screening Such a program could greatly increase the availability of spectacles in the developing world, but would be dependent on accurate autorefraction. In this study we performed subjective refraction and autorefraction on a population of Indian adults aged 50 years and over to assess the accuracy of autorefraction relative to subjective refraction
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