Seeing is believing – or is it the other way around?

A new monofocal lens now being developed in Israel could solve the problems experienced by people wearing bifocal and multifocal glasses.

Zeev Zalevsky 521 (photo credit: Courtesy)
Zeev Zalevsky 521
(photo credit: Courtesy)
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 Zeev Zalevsky, professor of engineering at Bar-Ilan University 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.
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.
“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.
Rather than make do with the partial solutions available today, Zalevsky suggests a monofocal lens which can focus light from between 33 centimeters away up to the horizon. The lens is engraved with special patterns which shift the phase of light waves, enabling clear focus on objects both near and far.
“We call this an interferometric solution, combining the best of refractive and diffractive lenses,” Zalevsky says.
The solution consists of a single lens that enables wearers to see more clearly, no matter what their vision problem (presbyopia, astigmatism, etc.) or whether they wear glasses, contact lenses or intraocular lenses.
“If you wear bifocals, you will no longer have to move your head up and down to access the near or far vision areas – one pair of glasses with our interferometric solution will do the job,” he promises.
HIS COMPANY, Petah Tikvabased Xceed Imaging, has a dozen employees, and has been in business since he helped found it in 2007.
The company was started with private funding, and now has a d e v e l o p m e n t agreement with Bar-Ilan University. Zalevsky hopes that the first lenses based on his interferometric solution will hit the market within six months to a year.
“I believe this solution will help many people who in the past were only able to receive partial relief for their vision problems,” he says.
Xceed Imaging has commercialized the technology and is now c o n d u c t i n g clinical trials, w h i c h Zalevsky says have “proven very successful.
We hope to be able to market the lenses in the very near future,” he says.
One group he expects will welcome the lenses is comprised of those suffering from astigmatism, especially irregular astigmatism (where light is distorted in irregular patterns). Currently there are no reliable solutions for the condition, but Zalevsky says that Xceed’s products will greatly enhance focus for all astigmatism sufferers – including those with an irregular astigmatism condition.
In addition to the interferometric lens solution, Zalevsky is an inventor of note who has developed other winning ideas through better engineering.
In 2008, he won the International Commission for Optics 2008 prize “for his achievements and significant contribution in the field of optical super-resolution.”
Zalevsky shares a few of his other ideas, some of which are astounding.
Take, for example, his optical technique that will enable you to hear a conversation – or the heartbeat – of another person, without a listening device.
“Using a camera, computer and laser, we can optically measure vibrations and audio waves by illuminating scenery, watching reflections with a camera and analyzing images,” Zalevsky reveals. In fact, he adds, the technology is so precise that “we can differentiate between different people based on their position,” listening in on their conversation.
And while the technology clearly has security applications, “I think that biomedical applications are a much better opportunity for this,” he says.
Then there’s his plan for an endoscope that can go where no miniature camera has gone before – into the bloodstream.
“The average endoscope, at three millimeters in diameter, is too large for many applications, such as examining blood vessels or organs. In addition, most endoscopes can be used for either examination or treatment – not both. Our endoscope is 900 times smaller than the standard ones, and offers much better resolution.”
In addition, the endoscope has multifunctional capabilities in addition to imaging, such as electrical stimulation at its tip, Zalevsky says.
“We are developing a passive concentrator for photovoltaic electricity production systems that takes into account the limited movements of the sun across the sky, daily and at different times of the year,” he continues, explaining that his system will be able to more efficiently harness the sun for electricity production.
It sounds miraculous – but it's all in the optics, says Zalevsky, “and of course, good engineering!”