Super Vision in the Wink of an Eye

Sarina Tracy, sarina.tracy@photonics.com

It is, and has only ever been, an inquiring mind that leads to technological innovation. When scientists focus their attention on the “what ifs” in their investigative brains, it often leads to impressive discoveries. For Dr. Eric Tremblay at the Federal Polytechnic Institute in Lausanne, Switzerland (EPFL), his musings on telescopic sight and military optics could potentially turn into tangible results for those with age-related macular degeneration (AMD).

“At first it was mostly curiosity to see if it was possible to design a very thin reflective telescope that could fit into a contact lens,” Tremblay said. “We had been working on ultrathin reflective cameras a few years ago when Mark Neifeld, a professor at the University of Arizona, asked us if the same technology could be used for a telescopic contact lens. It then became part of a DARPA-funded research program to develop ‘hands-free zoom’ for soldiers.”

Photo courtesy of Dr. Eric Tremblay and Joe Ford, EPFL

Tremblay and his collaborators have created a telescopic contact lens prototype that could allow wearers to have telescopic vision. They have also created a technology that allows users to switch between normal and magnified vision just by winking. The contact lenses work by incorporating a very thin reflective telescope inside a 1.5-mm-thick contact lens. Small mirrors within the material bounce light around, expanding the perceived size of objects and magnifying the view.

“Although it was funded by DARPA for soldiers, the most obvious real use for such a contact lens would be as a visual aid for serious eye problems like age-related macular degeneration,” Tremblay said. “AMD is a huge problem, and a magnifying contact lens could be useful.”

The telescopic contacts are made using a rigid lens known as a scleral lens, which is larger in diameter than the soft contacts used more widely today. Although large and rigid, scleral lenses are safe and comfortable for special applications and present an attractive platform for optics, sensors and electronics. The prototype is made from several precision-cut pieces of plastic, aluminum mirrors and polarizing thin films, along with biologically safe glues.

For those without AMD, switching between normal and telescopic vision is crucial. The researchers developed electronic glasses that use a small light source and detector to recognize winks and ignore blinks. If a user winks, the functionality of the glasses changes. The glasses electronically select a polarization of light to reach the contact lens. The contact lens allows one type of polarization in the 1× aperture and another in the 2.8× aperture. The user then sees the view where polarizations of the glasses and the contact lens aperture match.

Before the lenses can be used in any practical way, however, the eye needs to have access to a steady supply of oxygen. Tremblay and his team have spent the past couple of years making the lenses more breathable by incorporating tiny air channels roughly 0.1-mm wide into the lens so oxygen can reach the cornea.

“Oxygen permeability is a major problem and the fundamental issue that needs to be solved before this could become a product,” Tremblay said. “Oxygen permeability is necessary for any kind of practical wear.”