Deviation caused by quality and matching problems of trial frame and trial lens

1. Deviation between optical center and geometric center of trial lens

The quality problems of the trial lens include the deviation between the optical center and the geometric center of the

trial lens. The deviation obtained by measuring the trial lens with plastic edge is between 0 ~ 1.0mm. The difference

between the two trial lenses is 0 ~ 2.0mm.

2. Deviation between the geometric center of the trial lens on the lens groove and the geometric center of the lens rim

of the trial frame

The matching problems between the trial frame and the trial lens, such as the mismatch between the diameter of the

lens slot of the trial frame and the diameter of the trial lens, or the mismatch between the width of the lens slot of the

trial frame and the thickness of the trial lens, resulting in the eccentricity of the trial lens placed on the lens slot of the

trial frame. Thus, the deviation between the geometric center of the trial lens and the geometric center of the lens rim

of the trial frame is generated. On the common trial frame, the deviation can reach 1mm. Therefore, the geometric

center difference of the test lens on the lens slot on both sides can be up to 2mm.

3. Deviation between the optical center of the trial lens and the geometric center of the lens rim of the trial frame

The above two deviations are combined into the deviation between the optical center of the trial lens and the

geometric center of the lens rim of the trial frame.