Does the Accuracy and Repeatability of Refractive Error Estimates Depend on the Measurement Principle of Autorefractors?

Purpose: The purpose of this study was to determine the accuracy and repeatability of refractive errors obtained using three autorefractors based on different measurement principles, vis-& agrave;-vis, gold-standard retinoscopy. Methodology: Accuracy of noncycloplegic, sphero-cylindrical refractive error of 234 eyes was obtained using the rotary prism-based RM-8900 closed-field autorefractor, photorefraction based Spot vision screener, wavefront aberrometry based E-see, and streak retinoscopy by four different examiners, masked to the results of each other. Inter session repeatability of autorefractors was determined by repeat measurements in a subset of 40 subjects. Results: Retinoscopy values of M, J0, and J45 power vectors for the cohort ranged from & minus;10.2 to 8 D, & minus;1.4 to 1.8 D, and & minus;0.9 to 1.2 D, respectively. Across autorefractors, the interequipment bias of M and J0 power vectors were statistically insignificant (< +/- 0.5 D; P > 0.05) but the corresponding limits of agreement were +/- 2.5 and +/- 1 D, respectively, without any trend across instruments or the patient's age (P > 0.5). Repeatability of M and J0 power vectors were +/- 0.75 D and +/- 0.40 D, respectively, across autorefractors. The range of J45 power vector was too narrow for any meaningful analysis. Conclusions: Refractive errors measured using autorefractors operating on different principles show minimal bias and good short-term repeatability but relatively large agreement limits, vis-& agrave;-vis, retinoscopy. Among them, the wavefront aberrometry based E-see autorefractor performs relatively better in all measurement parameters evaluated here. Translational Relevance: Although autorefractor estimates of noncycloplegic refractive error appears independent of their measurement principle, their relatively poor agreement with gold-standard retinoscopy warrants caution while used for screening and quantification of refractive errors. <comment>Superscript/Subscript Available</comment> ABSTRACT Purpose: The purpose of this study was to determine the accuracy and repeatability of refractive errors obtained using three autorefractors based on different measurement principles, vis-?-vis, gold-standard retinoscopy. Methodology: Accuracy of noncycloplegic, sphero-cylindrical refractive error of 234 eyes was obtained using the rotary prism-based RM-8900 closed-field autorefractor, photorefraction based Spot vision screener, wavefront aberrometry based E-see, and streak retinoscopy by four different examiners, masked to the results of each other. Intersession repeatability of autorefractors was determined by repeat measurements in a subset of 40 subjects. Results: Retinoscopy values of M, J0, and J45 power vectors for the cohort ranged from ?10.2 to 8 D, ?1.4 to 1.8 D, and ?0.9 to 1.2 D, respectively. Across autorefractors, the interequipment bias of M and J0 power vectors were statistically insignificant ( ?0.5 D; P 0.05) but the corresponding limits of agreement were ?2.5 and ?1 D, respectively, without any trend across instruments or the patient?s age (P > 0.5). Repeatability of M and J0 power vectors were ?0.75 D and ?0.40 D, respectively, across autorefractors. The range of J45 power vector was too narrow for any meaningful analysis. Conclusions: Refractive errors measured using autorefractors operating on different principles show minimal bias and good short-term repeatability but relatively large agreement limits, vis-?-vis, retinoscopy. Among them, the wavefront aberrometry based E-see autorefractor performs relatively better in all measurement parameters evaluated here.