There exists a fascinating observation in technology circles known as Moore’s Law, which states that the number of transistors in a computer chip doubles every two years. In that same vein, the law also indicates that the size of computer chip circuitry like processors, sensors and memory storage is also cut in half every two years. Moore’s Law has held true since its original formulation in 1965, and Intel predicts that 10nm computer chips will arrive within the next few years.¹ Such an advancement could have profound implications for integrating biosensors into contact lenses, allowing for revolutionary applications like monitoring the levels of glucose in a diabetic patient. 

Comprised of a number of different components, the tear film has enormous potential to provide us with valuable medical information about the health and wellbeing of the patient. A contact lens used as a biosensor could easily capture data on the various proteins, enzymes, lipids and salts within the tear film and translate it to practitioners in real time.²  Prototype biosensor lenses have already been used to investigate glucose levels and monitor intraocular pressure.^2-4 

Potential Setbacks
Measuring tear glucose levels using diagnostic devices is not a new concept. Reports of this technique being used date back at least two decades, and biosensor patents are a dime a dozen. Yet, some obstacles remain in the path of bringing such a device to market. The first is the problem of technology: glucose-monitoring contact lens devices are not yet refined enough for marketable use. In fact, the only contact lens device currently on the market is used to assess intraocular pressures. 

The second hurdle that must be overcome is more practical—supply and demand for such a device. Aside from considerations like manufacturing costs, there are a handful of medical conditions that would actually benefit from—or even require—continuous monitoring. Developing devices that require FDA approval for marketing is an expensive initiative. Accordingly, potential sponsors or manufacturers may be reluctant to commit the funding needed to bring such a product to market.² 

Despite these issues, however, it’s no surprise that contact lens biosensors are still viewed with excitement. Several different types have been considered, including colorimetric fluorescent sensors and electrochemical contact lenses sensors.² Another question remains, however: what impact will alternative wireless continuous monitors (for measuring other body fluids as well) have on the future development of lens sensors? Alternative devices are already available for patients using an insulin pump or other attachment devices worn on the arm or abdomen.^2,3 Other concerns relate to the variability of tear compositions and lag time for biomarkers to appear in tears compared with blood serum levels and the lag in recording time.^2,3 

I remain optimistic that as this technology evolves, contact lenses will eventually be used beyond their current indication for glaucoma and diabetes. Time will tell if we truly reach the “Holy Grail” or whether alternative devices will overtake the quest for the best contact lens biosensor in the diagnostic sector. For now, we’ll continue to watch as the story unfolds and prototypes advance.  

1. Clark D. Intel Rechisels the Tablet on Moore’s Law. Wall Street Journal, July 16, 2015, Available at: blogs.wsj.com/digits/2015/07/16/intel-rechisels-the-tablet-on-moores-law/.
2. Phan CM, Subbaraman L, Jones LW. The use of contact lenses as biosensors. Optom & Vis Sci. 2015 Dec. [Epub ahead of print].
3. Kudo, H, Arakawa T, Mitsubayashi K. Status of soft contact lenses biosensor development for tear sugar monitoring: A review. Wiley Peer Review Resources. 2014 Nov.
4. Zhang J, Hodge W, Hutnick C, Wang X. Noninvasive diagnostic devices for diabetes through measuring tear glucose. J Diabetes Sci Technol. 2011 Jan 1;5(1):166-72.