Abstract
Purpose: :
The study objective was to evaluate the accuracy of an automated refractometer and a wavefront aberrometer in predicting subjective refraction findings.
Methods: :
Refraction was measured in 180 eyes of young adult subjects aged between 18 and 45 using an autorefratometer (Canon 1000, Canon, Japan) and a wavefront aberrometer (irx3, Imagine Eyes, France). Besides, the subjects' subjective refractions were evaluated using trial lenses and a Bailey Lovie chart, following a preliminary retinoscopy examination. The objective automated refraction findings were expressed in the form of power vectors (M, J45 and J180) and compared with subjective measurements, used as reference values. In the case of wavefront outcomes, two different metrics were used to calculate sphero-cylinder refractions: one was based on second-order Zernike coefficients only while the other took into account higher-order aberrations. The results were analyzed using linear regression and displayed in the form of Bland-Altman plots.
Results: :
High correlations (R²>0.85, p<0.01) were found when comparing objective versus subjective findings. The correlations were similar for the autorefractometer and the wavefront aberrometer. For the wavefront method, higher accuracy and precision were found when high-order aberrations were taken into account.
Conclusions: :
Objective refraction measurements were able to predict subjective findings with a precision better than half of a diopter.
Keywords: refraction • aberrations