By Shirley Ha, BSc. (Hons), O.D.
Imagine real-time data and information streaming in a mid-air, 3D interface (think Tony Stark in Iron Man). But instead of the heavy suit and headgear, it involves “smart” contact lenses that provide biofeedback and enhanced vision simultaneously.
Welcome to the future – a world of augmented reality featuring contact lenses that monitor your health, thanks to the melding of nanotechnology, biosensors and visual digital information that you can manipulate physically.
Sounds too futuristic? It’s not. Researchers and bioengineers around the world are working on these devices, including lenses that dispense medication1,2. Some even have stem cells growing on them.3 While many are still in the form of prototypes, others are awaiting or undergoing human clinical trials. And one is already on the market.
Switzerland’s SENSIMED Triggerfish®, with the Canadian distribution by Labtician Ophthalmics anticipated to begin around February 2013, is the first commercially available device that continuously monitors intraocular pressure (IOP) variances and provides a 24-hour IOP profile of a glaucoma suspect/patient.4 It consists of a single-use contact lens with “strain” sensors that measure changes in corneal curvature, along with a self-adhesive antenna around the eye and a portable recording device. The two to three annual recordings of when transient IOP peaks occur in a 24-hour period are intended to help the physician monitor and manage a patient’s personalized treatment plan. While it has been sanctioned by Health Canada, at the time of writing, the device was undergoing clinical trials (19 registered) in the U.S. and has not yet received the Food and Drug Administration’s approval.5,6
Another remarkable IOP-monitoring sensing technology comes from the University of California, Davis and uses a drop of liquid to gauge pressure. Like “smart gloves” that can give physicians the enhanced ability to measure firmness of tissues and detect tumors, the flexible sensor relies on the increase in capacitance at the electrode of a single droplet of liquid within a “smart” contact lens as it is pressed by the firmness of the cornea.7
In London, ON, Dr. Jin Zhang and her group at the University of Western Ontario developed sensors with nanostructured optical probes embedded in contact lenses that change colour, depending on the wearer’s biomarkers, i.e., glucose levels in the tear layer instead of in the blood.7,9 She hopes her innovation will become the, “safe, sensitive and cost-effective glucose diagnostic tool and monitoring solution,”10 for diabetics around the world and that it will be extended to help people with other chemical imbalances such as calcium and potassium.11
In May 2012, a team led by organic chemist Dr. Jun Hu at the University of Akron in Ohio announced a glucose-sensing coating containing a boronic acid derivative12 on their colour-changing contact lenses for diabetics. Because only one of the contact lenses worn will have the coating and can change colour, he is designing a smart phone application to record the colour difference and quantify the glucose levels.13
Instead of chemically induced colour-changing contact lenses, Dr. Babak Parviz at the University of Washington in Seattle and his international team of researchers used amperometric sensing to detect glucose levels in the tear film.14 His sensors measure changes in tiny currents through the tear layer between sets of electrodes. Early tests on rabbits showed they could accurately detect even very low glucose levels.
Dr. Parviz, a pioneer in “smart” contact lenses, and his team have also been working on computerized contact lenses with display technology. They have already proven they can shrink electronics and wirelessly power red and blue light-emitting diodes (LEDs) embedded in a contact lens.15 In November 2011, his team successfully activated their prototype electronic contact lens with an unfocused, single-pixel, blue LED on a live, anaesthetized rabbit eye with no adverse effects to the rabbit’s cornea. Unfortunately, while the researchers were able to power the lens from about one metre away in vitro, the distance dropped to about two centimetres in vivo. Dr. Parviz’s goal is to design a better focused, full-colour, higher-resolution display lens that uses internal or less energy to power.
These breakthroughs led Microsoft Research to partner with Dr. Parviz’s lab in December 2011. They are now developing a “functional” contact lens that will monitor blood sugar levels through tears and provide real-time feedback wirelessly to an external local device, with the eventual goal of merging Dr. Parviz’s technology to stream data seamlessly onto a person’s field of view.16
We can look forward to exciting times as researchers continue to add miniaturized capabilities to contact lenses with improving nanotechnology. From web surfing to navigating to up-to-date health and safety monitoring – the possibilities are endless. And all of this is without the need for physical headgears, electronic screens or communication devices. The future looks very bright indeed.
References:
1 PENG, C.C., BURKE, M.T., CHAUHAN, A. “Transport of Topical Anesthetics in Vitamin E Loaded Silicone Hydrogel Contact Lenses”, Langmuir, vol. 28, no 2, 2012, p.1478-87
2 TIEPPO, A., WHITE, C.J, PAINE, A.C, VOYLES, M.L, MCBRIDE, M.K, BYRNE, M.E, “Sustained in Vivo Release from Imprinted Therapeutic Contact Lenses”, Journal of Controlled Release, vol.157, no3, February 2012, p.391-7
3 Centre for Eye ResearchAustralia: News Archive. “Stem Cell Treated Contact Lenses to Repair Damaged Eyes”, June 2012. Available at: http://www.cera.org.au/news/61/124/2012-06-18/stem-cell-treated-contact-lenses-to-repair-damaged-eyes/?page=1 (Accessed August, 2012)
4 Company website. Sensimed AG. www.sensimed.ch (Accessed August 2012)
5 MANSOURI, K., WEINREB, R.N. “Meeting an Unmet Need in Glaucoma: Continuous 24-h Monitoring of Intraocular Pressure”, Expert Review of Medical Devices, vol. 9, no 3, May 2012, p. 225-31
6 ClinicalTrials.gov – a service of the National Institutes of Health. Search: Triggerfish. Available at: http://clinicaltrials.gov/ct2/results?term=triggerfish (Accessed September 2012)
7 NIE, B., XING, S., BRANDT, J.D., PAN, T. “Droplet-based Interfacial Capacitive Sensing”, Lab on a Chip, vol. 12, no. 6, 2012, p. 1110-1118
8 COLLIER, R. “Rosy Outlook for People with Diabetes”, Canadian Medical Association Journal, vol. 182, no 5, March 2010, p. E235-6
9 ZHANG, J., HODGE, W., HUTNICK, C., WANG, X. “Noninvasive Devices for Diabetes through Measuring Tear Glucose”, Journal of Diabetes Science and Technology, vol. 5, no 1, January 2011, p. 166-72
10 ZHANG, J. “Development of Non-invasive Diagnostic Device for Diabetes”, Canadian Rising Stars in Global Health – Round 1 Grantees, grandchallenges.ca, June 2011. Available at: http://www.grandchallenges.ca/canadianrisingstars_round1grantees/jinzhang_en/ (Accessed August 2012)
11 GILLESPIE, B. “Seeing Red”. Innovation.ca, July 2010. Available at: http://www.innovation.ca/en/ResearchInAction/ImpactStory/Seeingred (Accessed August 2012)
12 Patent: Optical Device and Method for Non-invasive Real-time Testing of Blood Sugar Levels. Available at: http://patentscope.wipo.int/search/en/detail.jsf?docId=WO2011034592&recNum=1&maxRec=&office=&prevFilter=&sortOption=&queryString=&tab=PCT+Biblio (Accessed August 2012)
13 BATES, C. “Colour-changing Contact Lens Could Replace Painful Skin Pricks for Diabetics”, May 2012. Available at: http://www.dailymail.co.uk/health/article-2149276/Colour-changing-contact-lenses-replace-painful-skin-prick-tests-diabetics.html (Accessed August 2012)
14 YAO, H., SHUM, A.J., COWAN, M., LAHDESMAKI, I., PARVIZ, B.A. “A Contact Lens with Embedded Sensor for Monitoring Tear Glucose Level”, Biosensors and Bioelectronics, vol. 26, no 7, March 2011, p. 3290-6
15 LINGLEY, R., ALI, M., LIAO, Y., MIRJALILI, R., KLONNER, M., SOPANEN, M., SUIHKONEN, S., SHEN, T., OTIS, B.P,. LIPSANEN, H., PARVIZ, B.A. “A Single Pixel Wireless Contact Lens Display”, Journal of Micromechanics and Microengineering, vol. 21, no 12, November 2011, p. 1-8
16 Microsoft Research. “Functional Contact Lens Monitors Blood Sugar Without Needles”,December 8, 2011. Available at: http://research.microsoft.com/en-us/collaboration/stories/functionalcontactlens.aspx (Accessed August 2012)
