Accuracy of WASCA aberrometer refraction compared to manifest refraction in Chinese adult myopes.

PURPOSE To investigate the accuracy of the Carl Zeiss Meditec Wavefront Supported Custom Ablation (WASCA) aberrometer in refraction testing for Chinese myopic adults. METHODS Manifest refraction and WASCA were performed on 360 eyes of 360 consecutive Chinese myopic adults without cycloplegia. Both vector analysis and conventional notation were applied for comparing results, and differences between WASCA and manifest refraction for each component were calculated for accuracy evaluation. Correlation coefficients, regression equations, and mean errors of each component between the two methods were also tested. RESULTS Pearson correlation coefficient for M, J(0), J(45), sphere, and cylinder was 0.9680, 0.9320, 0.8655, 0.9668, and 0.8761, respectively. Mean error for the components above was -0.39+/-0.71 diopters (D), -0.02+/-0.16 D, 0.01+/-0.12 D, -0.42+/-0.70 D, and 0.06+/-0.30 D, respectively. In patients whose manifest vector M was < or =-6.00 D, mean errors of sphere and vector M were larger than the remainder of the study group. Ninety percent cylinder errors were within +/-0.50 D. Mean error of axis was 7.4 degrees, with 50% of eyes within 5 degrees. In cases with < or =-0.75 D astigmatism, mean error of axis was 9.8 degrees, which was larger than the remainder of the study group by 4.9 degrees. CONCLUSIONS For Chinese myopic adults, the concordance between WASCA and manifest refraction is, on average, high. However, for eyes with low to moderate spherocylindrical refraction, WASCA is less accurate in predicting sphere and vector M. It is also less effective for the measurement of axis in patients with astigmatism <0.75 D.