Provide a valuable resource to your clients or customers by linking to this resource page. Just place the following link on your website.
A spectacle lens (usually plastic or glass) designed with a continuous, gradual change in optical power from the top of the lens (distance vision) through a corridor to the bottom (near vision).
read more about gradient power lens ...These are overwhelmingly known as Progressive Addition Lenses (PALs) or simply "progressives," designed to correct presbyopia without the visible line of a bifocal.
The power smoothly "gradients" from the required distant prescription at the top, through intermediate viewing power in the middle, to the full reading addition at the bottom.
Due to the continuous change in curvature, the peripheral areas of the lens contain unwanted astigmatism, which can cause a sensation of distortion or "swim" when moving the head.
The design is called progressive because the change in power is continuous and additive, increasing gradually from the distance power to the full reading power.
Adaptation is required, especially for new wearers, due to the peripheral distortion and the need to learn to point the nose at the target object (not just the eyes).
Yes, but "office" or "room" progressive designs are often preferred as they widen the intermediate and near zones, optimizing for desk-based tasks.