Last week, researchers from the University of Washington and Aalto University reported that they had designed, constructed, and tested in vivo an LED contact lens display. The display was powered wirelessly and consisted of only a single LED light, but it could be controlled by computer. Although the initial test model was only a single pixel, researchers claim that they have already developed a micro-Fresnel lens that would allow multiple-pixel displays to be clearly discernible by a wearer. Although some think that this technology might represent the next phase in the evolution of ever-more personal computing, the visual equivalent to the Bluetooth earpiece that will allow people to use their smartphones without actually looking at the display, I believe that experience with contact lenses has taught us this technology is likely a dead-end that will, at best, have a few years of faddish popularity.
First, let’s consider what researchers have accomplished. They created an LED display on a contact lens. To accomplish this, they put wiring to serve as an antenna that can receive signals and channel power to the LED. When the lens was sitting in free space, it could be powered from up to three feet away, but when it was on the eye, its effective range dropped to less than an inch.
The lens itself is made of polyethylene terephthalate (PET to you and me), because it is chemically resistant, thermally stable, and transparent. However, PET is a terrible material to make contact lenses out of because it is hard and doesn’t allow airflow to the eye, so you’d only be able to use the lens for a few minutes at a time. And since the surface of your eye is actually too close to allow you to focus on the display, it would require a series of micro-Fresnel lenses to focus light from the display. Invented in 1822 by French physicist Augustin Fresnel, Fresnel lenses use concentric prismatic structures to capture and refract light in the intended direction. Testing of the micro-Fresnel setup showed that it could be used to separate the incoming light into a tiny 3×5 array on the rabbit’s retina.
But despite the apparent promise of this technology, I personally do not think it will have much success. Let us assume that many of the limitations of the initial research model will be overcome, that the contact lens will be able to be made as comfortable and effective as regular contact lenses–their popularity will still be limited. Why? Because contact lenses are so inconvenient and uncomfortable that they have driven hundreds of thousands of people to LASIK.
If you are a contact lens wearer, you know about the limitations of contact lenses, the irritation of the eye, and the necessity of cleaning the lenses. Even with regular cleaning, contact lenses are prone to develop bacterial films, which can in turn lead to vision-threatening eye infections. Disposable contact lenses are for that reason the norm, but if your contact lens was printed with possibly hundreds of dollars worth of circuitry, would you really want to get rid of it, or would you be more likely to cheat and take the risk of eye infection?
And what if you lost one of these contact lenses at a party or when walking down the street? How often do you actually find the lens, and how often does it end up lost? Now, again, imagine that that lens has several hundred dollars of circuitry printed on it.
Better solutions for integrated visual displays already exist. For example, researchers in 2005 reported a method that involves replacing the eye’s natural lens with an LED-array that is capable of projecting visual data onto the retina. The implanted array could be designed to switch between rebroadcasting visual data received on the back of the lens and a computer display.
An even more promising option, I believe, is to bypass the eye altogether. Subretinal implants have been shown to be able to stimulate the central visual system directly. Although these are currently being studied to restore sight to the blind, once perfected they can be used to transmit any kind of visual data to the optic nerve, including a computer display.
However, any of these techniques is likely a decade or more from implementation, and time will tell which approach proves most practical.