The calculations are again performed with the thin lens approximation at every point on the sphere of vertices, as explained with reference to step 30. At the end of step 40, the eye movements and, possibly, head movements making it possible to correct these prismatic deviations have been dete...
The lens movement protocol rejects progressive addition lenses that are not oriented vertically with the near reading portion towards the lensmeter and the distant field portion disposed to the operator. This assures uniformity of mounting of the lenses with respect to eye frames as well as designatin...