Advantages and adaption of progressive lenses

Tuesday, September 29th, 2009 at 1:58 pm Post in Eyeglasses

Progressive lenses are a significant breakthrough since they offer a much better solution to people who need reading glasses. In the past, presbyopic individuals had only bifocals and trifocals with visible lines for selection. Eliminating those visible lines, progressive lenses are sometimes called no-line bifocals.

In fact, progressive lenses have more advantages over bifocals and trifocals. As the name suggests, progressive lenses offer a progressive power transition, rather than just two or three lens powers. With progressive lenses, the wearer can achieve close vision, distance vision as well as intermediate vision through different parts of the lens. And they are easier for adaption.

Traditional bifocals and trifocals may bring “image jump” since they have sharply defined boundaries between different parts of the lenses. In contrast, progressive lenses offer a smooth and seamless power transition, so that images at varying distances are also smooth and comfortable. The fitting of progressive lenses involves a “corridor” of optimum vision, which runs vertically down the lens. This corridor should be placed in the right location, in order to get natural access to various powers.

In the past, frames for progressive lenses were relatively large, since the lenses should cover a wide range of powers. Small frames meant small close vision portion of the lenses. However, this situation is no longer true. Lens technological advancements have produced various effective solutions by introducing “short corridor” lenses. In addition, variations can be achieved by expanding different areas of the corridor. For example, progressive lenses for computer use have a wider intermediate zone by expanding the corridor’s intermediate area.

While progressive lenses offer clear vision at all distances, they still bring minor peripheral visual aberrations to a small portion of first-time wearers. These peripheral aberrations are caused by rapid visual movements from far right to left, especially when looking down. The result is burry vision. As a result, those people should move head slowly during the adjustment period. The adaption period varies from a few minutes to a few days, depending on personal situations. First-time wearers with high hyperopia always take a longer period to adapt to progressive lenses than those with mild hyperopia.

Nowadays, progressive lenses are available in materials including regular plastic, glass, polycarbonate and high-index. They have become the most popular choice for presbyopia correction.