Believe it or not, contact lenses are still an option for those who wear glasses that accommodate multiple prescriptions, but because of the unique approach they take to remedying vision problems, it can sometimes take over a month to get used to using them. Researchers at the University of California San Diego have created a better alternative with a prototype contact lens that can automatically switch between focusing on near or far objects by detecting the wearer’s eye movements.
It sounds like a medical breakthrough straight out of science fiction, and for the time being, it kind of is. It will take years before the contact lens can function as promised directly on a human eye. The prototype only functions in a special rig using several components that will have to be dramatically miniaturised before a human could wear it, and the test subjects look less than comfortable with a series of electrodes placed on their skin around their eyes. But it demonstrates some fascinating uses of existing technology that could make contacts a viable alternative for more users.
There are two parts to the new contact lens, as detailed in a recently published paper, “A Biomimetic Soft Lens Controlled by Electrooculographic Signal.” The first is the lens itself, which mimics how the lens in the human eye works. Instead of organic tissue, it’s made from layers of stretchy polymer films that change their structure when an electrical current is applied. In this case, wires deliver electricity from an external power source which causes the layers to either expand, reducing the lens’s thickness, or contract, which has the opposite effect. (Imagine a squishy ball getting thinner as you squeeze it.) In either behavior, the focal point of the light passing through the artificial lens is altered, which defines what in front of the lens appears in focus.
A look a the rig that researchers used for their tests.
The more interesting part of this research, however, is how the contact lens would be controlled. Instead of buttons that the wearer would need to press, the lens would be able to detect the Electrooculographic signals generated by the human eye. You might not realise it, but there’s an electrical field found in the tissues that surround the human eye, and a measurable potential difference between the front and back of the eye. By placing electrodes on the skin around the eye, that difference can be measured as the eye moves, allowing those movements to be tracked and translated elsewhere.
It’s an approach that’s already been used to allow those with very limited body movement to control and steer a wheelchair, but the researchers here believe those changing electrical fields could also be tapped to control their contact lens. Looking down, for instance, could automatically make the lens focus on near objects, such as the words on a page in a book, while glancing back up would automatically adjust the lens to focus on a wider, far-off vista. The sensitivity of the system could even be tuned to detect multiple blinks of an eye, which could potentially switch the lens to function like a telephoto zoom lens.
There’s a lot of refinement needed before glasses wearers would even consider switching to a contact lens that offered such functionality. Few of us are willing to walk around with electrodes stuck all over our faces, so considerable refinement would be needed to attempt to integrate all of the requisite electronics into the lens themselves. That will require some major breakthroughs from companies with lots of funding to spend on R&D, however. Even Google gave up on making a smart contact lens to monitor blood sugar levels, but if a company like Johnson & Johnson ever figured this out, who would even wear glasses again?
Featured image: University of California San Diego (Wiley Online Library)