When wearing presbyopic glasses for the first time, it is necessary to understand the proximity PD (pupil distance). Due to the convergence effect of the human eye when approaching, the visual axis rotates inward, making the proximity PD (taking the reading distance of 33cm as an example) 4-6mm smaller than the distance PD (head up). Presbyopic glasses have an important optical indicator OCD (horizontal distance between the optical center points of two lenses), and OCD and proximity PD should be as consistent as possible. According to national standards, there is a difference range between the two. The sunset red reading glasses have a tolerance of ± 3mm according to relevant national standards, which means that for a customer with a near use PD=62mm, the OCD value of the reading glasses to choose can be between 59-65mm. But the best solution is to choose glasses with an OCD value less than the distance between the pupils. Wearing glasses with an OCD value much greater than the distance between the pupils can cause eye soreness, fatigue, and inability to concentrate. If the pupil distance of the guest is too small or too large, making it impossible to choose the final lens and assemble the lens (without oversized frame or large area), then a non focal presbyopic lens is the best choice.