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Diagnostic accuracy and variability of autorefraction by the Tracey Visual Function Analyzer and the Shin‐Nippon NVision‐K 5001 in relation to subjective refraction
Author(s) -
Cleary G.,
Spalton D. J.,
Patel P. M.,
Lin P.F.,
Marshall J.
Publication year - 2009
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.2008.00627.x
Subject(s) - subjective refraction , autorefractor , refraction , mathematics , mean difference , refractive index , medicine , significant difference , optometry , optics , refractive error , physics , ophthalmology , statistics , visual acuity , confidence interval
Purpose: To determine the accuracy of distance autorefractions obtained by two ‘open field’ devices, the Tracey Visual Function Analyzer and the Shin‐Nippon NVision‐K 5001, by comparison with subjective refraction. Methods: Both eyes of 50 healthy phakic participants underwent subjective refraction. Autorefractions were then performed on undilated pupils using the Tracey and a modified Shin‐Nippon autorefractor and these were repeated within 50 days. Agreement with subjective refraction was calculated for sphere, mean spherical equivalent (MSE) and cylindrical vectors J 0 and J 45 . Intratest and intertest variability were also evaluated. Results: The mean age of the participants was 37.4 years. Subjective refraction MSE ranged from −6.25 D to +3.62 D, mean −0.49 D ± 1.79 D. Bias between subjective refraction and Tracey was −0.001 D, +0.045 D, +0.017 D, and −0.015 D for sphere, MSE, J 0 and J 45 respectively; these were not significant. Bias between subjective refraction and Shin‐Nippon was +0.004 D, +0.033 D, +0.106 D, and −0.021 D; only the J 0 vector was significantly different ( p < 0.0001) although this difference was small. Intratest variability for Tracey was low, measured at 0.189 D for sphere and 0.178 for MSE, and for the Shin‐Nippon 0.099 D and 0.086 D respectively. Tracey intertest variability revealed small, statistically significant bias for sphere and MSE (+0.071 D and +0.070 D, p = 0.011, 0.013). Shin‐Nippon reproducibility showed no significant bias. Conclusions: Autorefraction measurements captured by both the Tracey and Shin‐Nippon devices agree well with subjective refraction. The Shin‐Nippon shows lower intratest variability.