Figure 1
From: Photorefraction estimates of refractive power varies with the ethnic origin of human eyes

Raw data of the defocus calibration protocol obtained from a representative Indian subject.
Abscissa shows the range of trial lenses used to induce anisometropia while the ordinate shows the refractive error recorded by the PowerRef 3™ for each induced lens power. The diagonal black line indicates the ideal line with unity slope. The solid blue line indicates the best-fit linear regression line to the data of output anisometropia versus induced lens power. Error bars show ±95% confidence intervals.