What is the progressive multifocal lens?
The lens of progressive multifocal glasses can change the refraction of the lens at the upper part of the central channel of the line of sight, which can effectively solve the difference of refraction when people view objects at different distances from long, medium, and short distances. Depending on demand, people have the flexibility to change or compensate vision according to visual distance, making it easier to help to adjust your vision in a variety of situations.
Design principle of progressive multifocal lens
For the same piece of the lens, the top is used to see far, the bottom is used to see close. The upper and lower degrees are different.
There is not a sudden change in the distance degree fixed above the lens to the near degree fixed below the lens, but a gradual transition between the two through gradual changes in refractive power, which has special benefits over common bifocals or trifocal lenses.
The inadequacies of bifocals
The field of vision is smaller than that of the single vision lens, especially for the close view. For example, reading and reading newspapers need to make it coordinated with the head movement, there are optical defects of image jump and image displacement. There is a boundary, and it is easy to be seen that wearing a bifocal lens exposes age. Bifocals clearly demarcate the near and far regions, affecting appearance and vision. And when far view and close view change, the objects will jump. Because most myopic patients have a lag in the adjustment response, wearing bifocal lenses not only does not delay the development of myopia but has side effects. Therefore, bifocals are not suitable for teenagers to control myopia, and only a few special patients need to wear bifocals.
Advantages of progressive multifocal lenses
The progressive multi-focal lens has a number of different focal points from top to bottom. There's a smooth transition between seeing far and seeing close. There is no clear dividing line in the middle, like the myopia glasses, quite beautiful, and it is not dangerous. Because the added value is continuously and slowly increased in the gradient area, the wearer can get a continuous clear vision from the far point to the near point through the progressive lenses with the appropriate head position. In line with physiological optics, They help a better adaptation. Since the lens degree changes little by little, there is no phenomenon like jumping. Because the degree of the lens is gradual, so the vision from far to near changes slowly increase, which will not produce the adjustment of the eye fluctuation. It is not easy to cause visual fatigue. Without a degree line, the appearance will be more beautiful. Clear vision can be obtained at all distances within the visual scope. A pair of glasses satisfies both close and middle distances.