Progressive addition lens with fixed channel length

Abstract

The invention relates to a progressive addition lens with fixed channel length. The progressive addition lens comprises a distant vision zone, a near vision zone and a progressive channel. The length of the progressive channel having a focal power change amount being 85% of additional focal power on different lens meridian lines with different additional focal powers is 15mm. A vision clear range (astigmatism smaller than 0.25 diopters) on the progressive channel penetrates through the distant vision zone and the near vision zone. The vision clear range of the distant vision region has a sector shape with a 90-degree to 120-degree central angle; the vision clear range of the near vision region has a bell shape facing downwards and having a 37-degree to 57-degree flare angle; and the focal power change is smaller than 0.25 diopters in the vision clear range of both the distant vision zone and the near vision zone. According to the invention, the contour line distribution is obtained by dissolving Laplace's equation by a numerical method; an arctan function serves as the meridian line of the lens; and surface rise data of the lens to be processed can be obtained by designing the focal power distributions on the contour line and the meridian line cooperatively. The lens provide by the invention can effectively improve comfort of wearers.

Description

technical field [0001] The invention relates to a progressive multi-focal ophthalmic lens, in particular to a progressive multi-focal ophthalmic lens whose additional power has less influence on the length of the progressive channel and the far and near vision areas. Specifically, it relates to the characteristics and design method of the lens. This kind of lens can be used for mold making outer progressive lens and batch mold pressing inner progressive lens at the same time. Background technique [0002] Progressive multifocal ophthalmic lenses can meet the needs of distance vision and near vision at the same time, and avoid the defects of bifocal lenses such as vision breakage when switching from distance vision to near vision. At present, the application of progressive multifocal ophthalmic lenses is becoming more and more extensive. See attached figure 1 , The surface of the progressive multifocal ophthalmic lens is divided into a distance zone 1, a gradient channel (...

AI Technical Summary

Problems solved by technology

There are also some progressive multifocal ophthalmic lenses with shorter channel lengths, but the clear vision area with astigmatism less than 0.25 diopters on these lenses is often too small, or the clear vision area with astigmatism less than 0.25 diopters cannot pass through the distance vision and near vision Area

This will affect the field of vision of the lens wearer, and will have to move the head frequently when observing a large range of objects, affecting the comfort of the lens wearer

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