Contact Lens Design & Materials
Are Bionic Contact Lenses in Our Future?
By Ronald K. Watanabe, OD, FAAO
Today's contact lenses are used for vision correction, cosmetic improvement, and to bandage ocular surface disorders. Much of this is fairly straightforward, though contact lens fitting for corneal irregularities can be quite complex and rewarding. Nevertheless, the future of contact lenses may become much broader than contact lens practice as we know it today. Here we'll look at a few recent developments.
Stem Cell Growth
Last year, a team at the University of New South Wales developed a technique to grow corneal stem cells on soft contact lenses. Researchers would harvest limbal stem cells from a patient blinded by infection or another corneal disease, then culture them within the contact lens. The lens was then placed on the patient's cornea and left there for several days.
It is reported to be a technically simple procedure and has the potential to help many people who are blind or visually impaired due to corneal disease.
A few recent reports have introduced novel uses of contact lenses for diagnostic purposes. Researchers at Carnegie Mellon University have developed a soft contact lens implanted with photonic crystals that can sense glucose levels in the tears of diabetic patients.
The sensor, which is located in the periphery of the contact lens under the lower eyelid, changes color as glucose levels change. Wearers are therefore able to monitor their blood glucose levels throughout the day without having to draw blood, which makes this task less painful and arduous. This may improve compliance and may have a big impact on the diabetic patient population.
Twa and colleagues (2010) evaluated a reverse geometry rigid lens with an embedded piezoresistive pressure sensor that can measure intraocular pressure. They found that this technique resulted in the ability to take prolonged IOP measurements with less variability compared to slit lamp mounted or handheld dynamic contour tonometers. However, investigators found that the GP lens used did not fit well on some eyes and therefore could not obtain measurements on those subjects. Also, the lens was connected to the pressure sensor by a wire that may have interfered with normal blinking and affected measurements. Wireless technology may reduce these limitations.
Speaking of wireless, a University of Washington research group is using nanotechnology to develop contact lenses embedded with tiny electronics to monitor and display various health measures by analyzing the biochemistry of the eye. They can monitor body temperature, blood glucose and cholesterol levels, fatigue, inflammation, and possible infections. This information can then be wirelessly transmitted to the wearer's e-mail or mobile phone, or can even be shown on tiny displays within the contact lens that are superimposed on the wearer's field of view. The lens can also surf the Internet via an embedded antenna and radio chip that is powered by radio waves. This technology has broad potential applications and is of interest to NASA.
Impact on Patient Care
The future of contact lenses is going beyond what we know today. Keeping up with these developments is not only interesting, but may also help us better manage patients in the future. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #181.
Dr. Watanabe is an associate professor of optometry at the New England College of Optometry. He is a Diplomate in the American Academy of Optometry's Section on Cornea and Contact Lenses and Refractive Technologies and is in private practice in Andover, Mass. You can reach him at firstname.lastname@example.org.