Smart Contact Lens With Embedded Microelectronics Promises Bright Future for Vision CorrectionSeptember 15, 2020 by Tyler Charboneau
Researchers at Imec and Ghent University have embedded microelectronics into a biocompatible "smart contact lens" to remedy a host of vision problems, from keratoconus to general light sensitivity.
A collaboration between Imec and their affiliate Center for Microsystems Technology has produced a contact lens-embedded, artificial iris. Powered by microelectronics, the device is aimed to combat vision issues that are difficult to treat.
Ghent University and Imec will perform clinical validation before officially launching the lens as a medical device. What issues is this "smart contact lens" addressing and how does the early prototype work?
Solving Complex Eyesight Problems
While many eye conditions are mitigated using traditional corrective lenses, others require a higher level of care.
Patients suffering from keratoconus and aniridia—two rare, yet major focus areas for Imec—can experience an aggressive progression of these conditions during their lifetimes. General light sensitivity and eye irritation caused by ocular allergies are other noteworthy conditions. Furthermore, patients suffering from conditions like migraines and dry-eye syndrome also experience chronic light sensitivity.
Patients with keratoconus experience a thinning cornea that eventually protrudes into a cone shape. Image used courtesy of the Mayo Clinic
There are several corrective options on the market for each of these eye conditions, but none are a one-size-fits-all solution. While soft contact lenses refract light and hard lenses can also help to reshape the cornea for better visual acuity, both lenses are sometimes insufficient. Surgery is one option, but risk factors, fears, and costs of operation drive patients away.
Imec claims that over 20 million people with these issues can benefit from the new device underway. Imec and Ghent University aim to curtail the severity of these vision problems—ones for which we don’t have universally-dependable countermeasures. Their research, which is published in the journal Nature, has a chance to markedly improve patient outcomes, and non-invasively at that.
Breaking Down the Technology
The new, smart contact lens, dubbed Azalea Vision, shares operative similarities with camera lenses, including an adjustable aperture to allow dynamic visible light transmittance (VLT). The amount of light our eyes collect influences how we perceive colors and its refraction ultimately determines visual clarity.
The artificial iris contact lens. Image used courtesy of Imec
An Embedded Iris
The iris is embedded within the lens itself. It is constructed of concentric rings laid atop integrated LCD cells. These cells are combined with a thin-film transistor (TFT). This glass layer, combined with a layered semiconductor material, supports the LCD matrix and improved optical quality.
Transmittance variation relies on electric charges, and thus the Azalea lens contains embedded electrodes. Generated electric fields influence light absorption across the LCD rings. These electrodes control how each liquid crystal cell turns on and off. Photovoltaic cells provide power across the lens.
The LCD is a guest-host (GH) variant—meaning both liquid crystals and dichroic dyes are absorbing light. GH-LCDs absorb light variably at different angles and absorb wavelengths across the electromagnetic spectrum depending on their placement. Light transmittance is adjusted according to molecule location and polarization. This allows wearers to see both colored wavelengths and filtered white light.
Example of a guest-host display. Image used courtesy of Mingxia Gu
These LCD rings are great at tuning pupil size. However, GH technology’s typical sub 10:1 contrast ratio raises questions about the maximum light passage—primarily due to leakage. Azalea Vision’s primary strengths are controlling how light enters the retina and limiting transmission for sensitive wearers.
The iris leverages application-specific integrated circuits (ASICs). These customized ICs are often smaller than their FPGA counterparts while boasting higher processing power. ASICs commonly incorporate gate arrays (many millions of them on certain chips), and Azalea Vision’s particular design consumes very little power.
Another advantage of the ASIC setup is high compatibility with digital signal processors (DSPs)—commonly found within bio-implants.
Is It Biocompatible?
The smart lens’s composition is unique. Traditional lenses are made from plastics called hydrogels, which thrive structurally by absorbing water. These are generally biocompatible and don’t cause adverse bodily reactions during use.
Hydrogel-based contact lens. Image used courtesy of Feel Good Contacts
Introducing electronic components into the mix can complicate usage. Will extended wear trigger an immune response? Thankfully, the components are embedded within a scleral contact lens—a time-tested polymer lens already used by keratoconus patients. These are gas-permeable and comfortable to wear over time.
Due to the human eye’s curvature, the microelectronics contained within are flexible and thus adaptive to the user. Azalea Vision promises to improve visual depth of field for wearers—simultaneously reducing nearsightedness (myopia) and farsightedness (hyperopia).
From Research to Market
Early results are promising, though the R&D phase has not yet concluded for Azalea Vision. The existing device is a prototype, and we can thus expect more functional refinements prior to launch. Imec hopes to bring its research to market ASAP, though more testing and validation—not to mention approval from governing bodies—are still required.
There’s no denying that medical implants are becoming increasingly common. For some, contacts aren't a preferred option for vision correction due to insertion, removal, and wear comfort. Azalea Vision must entice these core wearers at a fundamental level, then assuage remaining safety concerns.
Ghent University also recognizes Azalea as a precursor to more research. “Several more startup initiatives are in preparation,” the researchers explain. Then, scientists will look to build upon the foundation laid by this small-yet-mighty device.