Sunglasses top power deviation

The nominal top power value of sunglasses should be 0.00D. Deviations during lens manufacturing or mismatched assembly of the lens and frame may result in top power
Deviation (i.e. with positive or negative top focus), if it exceeds a certain range, the wearer may feel visual distortion, and in severe cases, it can affect the wearer's visual health. Corresponding to the requirements of Table 1 of the national standard GB10810.1 "Glasses - Part 1: Single beam and multifocal lenses", the tolerance for the spherical lens top power is ± 0.12D; The tolerance for the top power of the column mirror is ± 0.09D.