Reading glasses; bifocals; multifocals. So much of what characterizes what is politely termed “the third plateau” is related to the deterioration of eyesight. And there’s a reason for that, says Ze’ev Zalevsky, professor of engineering at Bar Ilan University in Israel and inventor of a unique system to help improve the eyesight of those suffering from presbyopia, the weakening of the ability to focus on near objects.
“After age 45, your eyes gradually lose their flexibility, making it difficult to focus on close objects. If you had good eyesight previously, you may need reading glasses to focus on these near objects, while if you had further deterioration, you would need bifocals or multifocals to enable you to see close and at a distance,” Zalevsky explains to ISRAEL21c.
Eyeglasses, as they are used today, are not ideal solutions he says, because what you gain in eyesight magnification you lose in clarity and focus. It’s a problem that has plagued generations of eyeglass wearers, but Zalevsky believes he has found a better way.
One lens will do the job
“Spectacles” have been around for at least 700 years by most reckonings, and they seem to have been doing an adequate job of compensating for presbyopia, myopia and other common eye ailments. But that’s not always necessarily the case, Zalevsky says. For example, bifocals and multifocals, which are popular among older wearers, have several disadvantages. They simply draw the eye to the appropriate spot on the lens, while limiting the focus as regular glasses do. They also reduce the usable field of view. And while the refractive lenses used in most eyeglasses limit focus, diffractive lenses – which could solve the focus issue by increasing focal depth – have their own problems, such as color integrity distortion and low energetic efficiency.