Advancements in contact lens technology during the past 20 years have been tremendous in terms of repercussions on ocular health, visual performance and ease of prescribing by the ocular medical community. But, we can continue to look forward to new technology and new applications of contact lenses in patients’ everyday lives.

When explored, the possibilities are really quite limitless—and they open the door for an expansion of optometrists’ scope of practice. What factors currently impact our contact lens practicing habits? How will that continue on into the future? How will new applications of contact lens technology mesh with our daily lives?

Contact Lenses, Currently
One highlight of technological advancement in contact lenses is the improvement in oxygen permeability. The contact lens industry shouldn’t put the brakes on striving for even greater oxygen levels, even with the advent of silicone hydrogel materials.

Although recent studies suggest that the level of oxygen supplied by most silicone hydrogel lenses is adequate for maintaining corneal health, the bottom line is that the eye has the greatest likelihood of good health if it receives the highest amounts of oxygen.^1-3

Certainly, there are other factors that lead to successful contact lens wear, such as deposition likelihood, movement and wettability. But, if the cornea is designed for normal oxygen levels throughout the day and closed-lid compensation at night, then why should we settle for “adequate” oxygen levels in contact lenses? Even if there is no immediate risk to the eye, why apply even very low levels of hypoxia on the cornea if we can avoid it?

The contact lens industry focuses on Dk/t values and how those apply to corneal health. Yes, central corneal oxygen exposure is important; however, it is the peripheral cornea that is actually deleteriously affected by the lower Dk/t levels that are evident in all contact lenses. Dk/t has a much lower value in the thicker, peripheral contact lens material than at its center, which is usually what we pay most attention to.⁴

Remember, the limbus is the only source of epithelial stem cells, which help the cornea heal quickly and maintain normal function. If lower Dk/t values in the peripheral contact lens material cause hypoxic inflammation in the limbus, there is the potential for serious complications, such as chronic keratitis, vascularization and recurrent erosions.⁵

Practitioners should continue to use those contact lenses with the highest possible Dk/t values. Longer-term studies show that silicone-hydrogel wearers currently have indistinguishable corneas compared to non-lens wearing corneas.^6,7 Increased oxygen levels will limit the amount of chronic limbal inflammation, so industry leaders should continue to attempt to reach the highest oxygen levels possible. Continued improvements in oxygen flow are necessary to mimic “normoxia” conditions, which will be healthiest of all.

Vision Improvement
The word “aberrations” has a negative connotation in the optical world. However, aberrations have actually been used intentionally in multifocal contact lenses to give expanded depth of focus to presbyopic patients.

Continuing on that path of design, contact lenses can be developed with aberrations created specifically to negate the eye’s own aberrations. Instead of expanding the depth of focus, these lenses would help to improve the quality of single vision.⁸

But, the challenge in working with such lenses would be the fluctuation of the eye’s own aberrations over time. A lens that corrects for aberrations may not fully correct vision at all times, though creating an “adjustable” lens is a near possibility in the customizable contact lens realm.

Looking further to improve visual capabilities with contact lenses, some researchers have turned to nocturnal geckos as their ideal model. The multifocal optical systems of these creatures allow them to focus on objects at different distances, and they only have highly sensitive cones (no rods) in their retina, so they can actually see color at nighttime.9 An in-depth understanding of their visual system could allow us to develop more effective multifocal contact lenses for our presbyopic patients.

Clinical Wish List
Some of the basic, everyday issues with contact lenses could be improved with future technology. For example, what about designing a lens that disintegrated or drastically changed its comfort level after the specified wearing time?

Such advancements could help considerably to improve patient compliance, as well as reduce the risk for infections and other adverse contact lens-related events.

Or, another item on our “clinical wish list” would be a self-disinfecting contact lens. This would benefit not only those patients who prefer extended wear modalities, but daily wear patients as well.

Even if this worked in complementary fashion with current solution regimens, any improved microbial “control” of contact lens materials would only improve ocular health and infection/inflammation issues.

Contact Lens as Computer Monitor In 2008, Review reported on the successful creation of a contact lens with an embedded electronic circuit. This lens was tested for wearability in rabbits, and no adverse effects were demonstrated. At the time, the University of Washington researchers who created the lens hoped simply to prove the feasibility of the technology. The embedded circuit and lights didn’t yet function, and it was speculated that more complex circuitry could be included at the edge of the lens so as not to distort the user’s view. Researcher Babak Parviz, Ph.D., M.S., professor of electrical engineering at the University of Washington, has continued to develop this technology. His most recent prototype lenses are powered by radio waves and 330 microwatts of power from a loop antenna, and he says that future versions will be able to harvest power from a cell phone.1 This lens includes an LED that is powered wirelessly through radio frequency. Dr. Parviz suggests that the lens may be effective as a heads-up display or as a biosensor. 1. Micro Machines and Opto-Electronics on a Contact Lens. Available at: www.hplusmagazine.com/articles/toys-tools/micro-machines-and-opto-electronics-contact-lense (Accessed January 2009).

On the Horizon
Ocular drug delivery would be improved with the release of drug-eluting contact lenses.¹⁰ Currently, topical ophthalmic solutions are dosed in a pulse style, which results in a short-term overdose followed by a short period of effective therapeutic concentration and a longer period of under-dosing—and that’s if the patient is compliant with the regimen.

On the other hand, a sustained-release system for ophthalmic topical medications would neatly bypass such limitations and could be applied to either short-term antibiotic or long-term glaucoma therapy, for example. A contact lens can serve as the ideal vehicle for topical therapies, and the amount and rate of drug release can be varied by the polymers within the lens itself, in addition to the concentration of medication in the lens coating.¹⁰ This could serve as an effective method to sustain ideal intraocular pressures for glaucoma patients, for example, or help alleviate allergic eye disease for the contact-lens wearer during allergy seasons.

Initial studies show that drug release can be maintained at a steady rate for up to 100 days.¹⁰ The implications of this technology regarding patient compliance, effectiveness of dosing and ease of use are tremendous. Keep posted as this new application becomes more mainstream.

Also, consider the possibilities of biomarker detection via a contact lens. When you have a blood test, many of the biomarkers measured are found in the live cells of your body, including the surface of your eye. A contact lens could be used to monitor cholesterol and sodium levels, glucose levels—even hormonal fluctuations.

And, with the inclusion of nanotechnology, a wireless transmitter could relay all the pertinent data to the clinic or doctor instantaneously, with less room for human error.¹¹

In the Eye of the Beholder
The miniaturization of technology over the years has continued to challenge the status quo when it comes to computerized devices. Computers, for example, used to take up an entire room. Now, the technology is in the palm of our hands, with cell phones, smart phones and laptop computers. And the drive to shrink hasn’t stopped there!

To maintain momentum, it’s only natural to aim even smaller … such as a contact lens.

Many companies are designing such small circuits and displays that we could eventually conceivably watch television on our contact lenses. Body heat would power the display, and voice commands or gestures could change the channels.¹²

Along that same line, one day we may use contact lenses in place of mobile devices. The lens itself will superimpose computer-generated information and imagery onto the wearer’s field of vision—in the periphery, of course, so as not to interfere with his or her normal vision.

Technology such as this paves the way for augmented reality, which would overlay real-world images with computer-generated images and information about the area. For example, this technology could help a wearer fuse visuals of known landmarks with electronic information about the location, so that the wearer can plan out his or her next stop, find a place to stop and eat, get directions, or simply learn more about the location.

What’s Next?
The future of contact lenses is sure to include continued product innovation, possibly incorporating many of the concepts and ideas mentioned in this article. Keep in mind that the number of people who have myopia and presbyopia, two of the largest contact lens-wearing patient populations, is continuing to grow and will only add to the contact lens patient base worldwide. Additionally, the continued industrialization of hugely populated countries, like China and India, will add to the demand.¹³

Necessity may be the mother of invention, but when it comes to contact lenses, the future is already being paved with improved materials and lens designs. The industry should be prepared to keep up with demand and innovative, new products. Exciting developments in the contact lens world will govern patients’ expectations and the optometrist’s role in continued contact-lens expertise.

Dr. Wesley is in private practice in the Twin Cities Metro area. She focuses on primary care, children’s vision and contact lenses/anterior segment. She publishes and lectures regionally and nationally on a variety of ophthalmic and practice management topics.

1. Brennan NA. Beyond flux: total corneal oxygen consumption as an index of corneal oxygenation during contact lens wear. Optom Vis Sci. 2005 Jun;82(6):467-72.
2. Morgan P, Brennan NA. The decay of Dk? Optician 2004;227(5937):27-33.
3. De la Jara PL, Stretton S, LaHood D, et al. The future of contact lenses: Dk really matters. Contact Lens Spectrum. 2006 Feb. Available at: www.clspectrum.com/article.aspx?article=12953 (Accessed December 2009).
4. Holden BA, Sweeny DF, Vannas A, et al. Effects of long-term extended contact lens wear on the human cornea. Invest Opthalmol Vis Sci. 1985 Nov;26(11):1489-501.
5. Stapleton F, Stretton S, Papas E, et al. Silicone hydrogel lenses and the ocular surface. Ocul Surf. 2006 Jan;4(1):24-43.
6. Covey M, Sweeney DF, Terry RL, et al. Hypoxic effects on the anterior eye of high Dk soft contact lens wearers are negligible. Optom Vis Sci. 2001 Feb;78(2):95-9.
7. Brennan NA, Coles ML, Comstock TL, Levy B. A 1-year prospective clinical trial of balafilcon A (Purevision) silicone-hydrogel contact lenses used on a 30-day continuous wear schedule. Ophthalmology. 2002 Jun;109(6):1172-7.
8. Kollbaum PS. Seeing into the future with contact lenses. Contact Lens Spectrum. 2003 Feb. Available at: www.clspectrum.com/article.aspx?article=12295 (Accessed December 2009).
9. Gecko Vision: Key to Future Multifocal Contact Lens? Science Daily. Available at: www.sciencedaily.com/releases/2009/05/090507164407.htm (Accessed December 2009).
10. Ciolino JB, Hoare TR, Iwata NG, et al. A drug-eluting contact lens. Invest Ophthalmol Vis Sci. 2009 Jul;50(7):3346-52.
11. Electronic Contact Lenses Promise Future of Advanced Augmented Vision. Available at www.medgadget.com/archives/2009/09/electronic_contact_lenses_promise_future_of_advanced_augmented_vision_1.html (Accessed December 2009).
12. Nelson B. Vision of the future seen in bionic contact lens. 2008 Jan 21. Available at: www.msnbc.msn.com/id/22731631/ (Accessed November 2009).
13. Holden BA, Evans K. 2004: What’s next in contact lenses? Contact Lens Spectrum. 2004 Sep. Available at: www.clspectrum.com/article.aspx?article=12662 (Accessed December 2009).