THE NEXT 30 YEARS
CONTACT LENSES: THE NEXT 30 YEARS
How will contact lenses evolve between now and 2046?
HARVARD SYLVAN, OD
When I was first asked to write an article about what the contact lens industry might look like in 30 years, my initial thought was, “That is a very long time from now.” Then I thought, “What year was it 30 years ago?” That year was 1986. For those of you who are 55+, you may agree that 1986 seems like yesterday. Tempus fugit, doesn’t it?
Although technological changes seem to be increasing exponentially, the progress made during the last 30 years may give some indication of the time needed for new developments to take hold. Since 1986, the contact lens profession has changed significantly. In my opinion, the two most important advances were:
1) The development of frequent replacement and disposable lenses. In 1986, there were no frequent replacement lenses. Contact lenses came in individual vials. Diagnostic lenses were reused and had to be cleaned and disinfected before each use—not exactly convenient or as sanitary as using disposable trial lenses.
The advent of frequent replacement lenses in 1987 also changed the financial dynamics of contact lenses. Prior to frequent replacement lenses, a patient who lost or damaged a lens needed to reorder another lens. Calls for replacement lenses were a frequent, daily occurrence in every office that prescribed contact lenses. Individual lenses were significantly more costly compared to the frequent replacement lenses to which we are now accustomed. That situation created an entire industry revolving around lens replacement plans in which insurance policies were created to reduce the cost of replacing lenses. Many offices developed their own lens replacement plans by charging an annual fee that reduced the cost if a replacement was needed. That in turn created an annuity-like product for contact lens practitioners.
That all changed when frequent replacement lenses arrived. However, the benefits of frequent replacement lenses to patients outweighed the perceived financial loss to practitioners, and ultimately, frequent replacement lenses became the accepted norm when available in a patient’s prescription.
Initially, the first disposable lenses were intended for one-week extended wear. As the success rate for extended wear with these low-oxygen-permeable (low-Dk) lenses was not high but the cost was, practitioners started prescribing them as two-week, daily wear lenses. That was the origin of the two-week replacement modality. Daily disposable lenses are the most recent development in the disposable lens category.
2) The development of silicone hydrogel materials. Silicone hydrogel materials became available in 1999. Their initial usage was relatively low, as manufacturers first promoted silicone hydrogel lenses as an improved extended wear option. It wasn’t until the number of silicone hydrogel lens options multiplied and fitters believed in the value of higher-Dk lenses for daily wear that usage increased. Today, soft lenses account for about 88% of all contact lenses prescribed, and silicone hydrogel lenses constitute the majority of that number (Nichols, 2016).
There have been many other important developments during the past 30 years, including stable toric lenses, much improved multifocal lenses, reverse geometry designs that created successful orthokeratology results, and significant improvements to hybrid and scleral lenses. However, the advent of frequent replacement lenses and the development of silicone hydrogel materials have certainly had the most significant impact.
So what can we expect in 2046? There are many visionaries in our profession who are actively involved in research and development. Fortunately, many of these respected experts were willing to share their thoughts with me. What follows is a compilation of their responses as well as my own prognostications.
LENS MATERIAL ADVANCES
The consensus is that silicone hydrogel materials will still be dominant 30 years from now. As there are a limited amount of materials that are oxygen permeable, optically clear, water soluble, flexible (“soft”), comfortable, and cost effective to manufacture, any material improvement are expected to be made to existing silicone hydrogel materials rather than developing a completely new material. Of course, that does not mean that a new material won’t be developed, only that it is not known if and when that might occur. In the interim, modification to currently existing silicone hydrogels will be keeping research and development teams busy. What is known is that having materials with sufficient oxygen permeability has not significantly changed wearing outcomes. Material improvements, whether to new lenses or to existing silicone hydrogel materials, will be made to overcome two distinct challenges:
1) Increasing comfort to improve the wearing experience and reduce contact lens dropouts. Wearing a contact lens negatively impacts the tear layer by increasing pre-lens tear thinning and tear evaporation (Guillon and Maissa, 2008; Nichols et al, 2005). In addition, some studies show a correlation between the coefficient of friction and comfort (Kern et al, 2013; Coles and Brennan, 2012). It is well known that the primary reason for contact lens dropout is discomfort associated with dryness. Therefore, surface modifications will be made to current silicone hydrogel materials that will create biomimetic surfaces that more closely mimic tear chemistry and, hopefully, that reduce lens dehydration, the coefficient of friction, and the resultant lip wiper epitheliopathy. As the ability to diagnose dry eye etiology advances, it is conceivable that different surface modifications may be available and utilized depending upon the underlying cause of the dry eye symptoms.
2) Reducing the risk of contact lens-related microbial complications. Preventing bacterial adhesion and subsequent biofilm formation is of the utmost importance. Once a biofilm has formed, it is much more resistant to therapeutic control. Silicone hydrogel materials have not reduced bacterial adhesion; to the contrary, depending on the material, they may be more susceptible to bacterial adhesion compared to traditional hydrogel materials (Willcox, 2013). Researchers have been attempting to create anti-microbial lenses. Key considerations are preventing bacterial resistance and not disturbing the normal beneficial flora of the eye. There has been a promising development utilizing a chemical compound known as a furanone, which is not an antibiotic but instead prevents bacteria from communicating and forming biofilms. As it is not an antibiotic, bacterial resistance is not an issue.
Researchers at the University of New South Wales School of Optometry and Vision Science found that contact lenses on which melimine (a synthetic peptide made by combining melittin and protamine) was covalently attached demonstrated a highly efficient kill rate against Pseudomonas aeruginosa and Staphylococcus aureus as well as some significant reduction of Candida and Fusarium (at least 1 log unit) and Acanthamoeba (at least 2 log unit reduction) in rabbit eyes. The melimine-coated lenses were also effective against some known antibacterial-resistant strains. In addition, no cytotoxicity was noted in the rabbit eyes after 22 days of wear (Dutta et al, 2013). There has been a small clinical trial in which 17 people wore melimine-coated contact lenses for an average of seven hours. The results were encouraging; the only differences between the melimine-coated lenses and the uncoated control lenses were higher corneal staining with the coated lenses and a slight comfort preference for the control lenses (Dutta et al, 2014). Further clinical studies are planned for both furanone and melimine technologies. Perhaps these are the types of technologies that will be incorporated in all contact lenses by 2046.
Poor compliance with cleaning and replacing contact lens cases is a major source of microbial contamination; a recent study that tested 1,000 cases found the rate of microbial contamination by any organism to be 79% (Tilia et al, 2014). Those organisms can be transferred to the stored lenses and ultimately to the cornea.
Several new types of contact lens cases are being developed that will limit microbial contamination. Silver impregnated cases have been used. Although they do not prevent bacterial contamination, the number of bacteria is significantly reduced (Dantum et al, 2012). Other types are also being investigated. There is a case being developed that utilizes gold nanoparticles of varying shapes to identify bacterial contamination of a lens case (Verma et al, 2015). Each particular nanoparticle shape will be sensitive to a specific organism. A color change to the case will indicate which organism is present in sufficient enough concentration to cause that color change (Figure 1). That will alert wearers to discard their cases.
Figure 1. Gold nanoparticle contact lens case changes color when micro-organisms reach a certain level.
Despite these developments, the increase in usage of daily disposable contact lenses will certainly have the greatest impact on reducing any complications related to contact lens cases. This may ultimately reduce the research and development necessary to create antimicrobial cases, as there may be limited commercial value. It is conceivable that the technology used to identify bacteria in lens cases will be able to be applied to contact lenses to alert patients when bacterial adhesion reaches a certain level.
MODALITY AND MARKET SHARE
With no new material imminently available, the market share of soft lenses, GP lenses (including sclerals), and hybrids 30 years from now will most likely remain relatively similar to today’s percentages. Within the soft lens arena, almost everyone agrees that daily disposable lenses will be the predominant modality in 2046. If that is correct, the need for antimicrobial lenses and cases will certainly be lessened. Silicone hydrogel daily disposable lenses will be the preferred one-day material and will follow the same path that the silicone hydrogel frequent replacement lenses took: a slow uptake but eventual dominance as options increase and competitive market forces take place.
LENS DESIGN ADVANCES
In addition to expanding the base curve, power, and diameter options to the design of soft spherical and toric lenses, efforts will be made to increase tear exchange using features such as micro-channels on the back surface of contact lenses.
Most design efforts are expected to focus on improvements to multifocal and multifocal toric lenses. Further improvements will be made via individual customization. Current lenses have the optics in the center of the lens. A lens will usually center itself over the steepest part of the cornea, which is not necessarily the geometric center of the cornea. Even if the lens is centered, the visual axis is somewhat nasal to the geometric center. With the increasing availability of topographers, it will be easy to obtain information that will allow laboratories to manufacture lenses with the lens optics placed directly over the visual axis. This is especially critical for multifocal success.
As aberrometers become more commonplace as part of multi-function instrumentation, it may be possible to custom design aberration-control lenses that will improve vision for any soft lens wearer. Creating manufacturing efficiencies that will reduce cost will be essential for the widespread adoption of custom lenses.
Several groups are in the process of creating various new multifocal options that will not use simultaneous vision designs, as current multifocals do, but these options will use new technologies such as flexible optics, liquid crystals, and fluid dynamics to create self-focusing lenses that will be able to determine where the eye is looking, pupil size, eye position, etc., to facilitate a change in the lens power. An auto-focus contact lens is being developed, using technology based on the retina of the elephant nose fish, that will increase contrast and sensitivity—two problems encountered with multifocal contact lenses. This will not be a typical simultaneous vision lens, but will allow focusing the entire optic zone at whatever distance is being viewed (Figure 2).
Figure 2. Fish-inspired lens with multifocal optics.
Photochromatic contact lenses are a distinct possibility. Commercialization is possible in a few years. Certainly, by 2046, photochromatic lenses should be in common use.
FUNCTIONAL CONTACT LENSES
Perhaps the greatest change related to contact lenses during the next 30 years will be the reasons for which they are worn. Contact lenses won’t be limited to vision correction or cosmetic purposes. Numerous applications are already being developed:
1) Biometric Measurement Recently, the Triggerfish lens by Sensimed received U.S. Food and Drug Administration (FDA) clearance for use in measuring corneal curvature changes that can occur with variation in the intraocular pressure (IOP) in adults at least 22 years old. The silicone hydrogel contact lens is embedded with a strain gauge (a microelectrical mechanical sensor) that measures circumferential changes in the corneal-scleral region that result from changes in the IOP. The lens is worn for 24 hours to obtain a continuous reading. An antenna is placed around the eye with adhesive and wirelessly receives the data from the lens, which is transferred to a recorder worn by the patient. At the end of the wearing time, the data is wirelessly sent to the practitioner’s computer (which must have the necessary software installed). The data will give the practitioner a sense as to the diurnal variation and, therefore, the best time at which to measure the IOP.
Although the lens is not meant to be a diagnostic measurement of the IOP, Twa et al (2010) concluded that the IOP readings obtained were comparable to two other methods of testing that were used and had lower variability. However, a recent study found that if patients slept in a face-down position, higher limbal strain was noted and may indicate the need for a protective eye shield or something similar to prevent inaccurate readings (Flatau et al, 2016).
Glucose Sensing Several groups are developing glucose sensing contact lenses, including Google/Alcon, Microsoft, and others. Sensors are placed between the outside and inside surfaces of the lens so they don’t touch the cornea. A small pinhole allows access to the tiny sensor, which communicates wirelessly and sends data to a device such as a smart phone. The electronics are outside of the optical zone.
Researchers at the University of Western Ontario have developed a lens in which a portion of the periphery will change color if the glucose level in the tears exceeds a certain level, thus alerting the patient. A research team in Belgium is developing a contact lens that incorporates new monosaccharide fluorescent signaling boronic acid-containing probes that enable the measurement of glucose concentration in the tears. All are in development, but I envision that they will be commercially available prior to 2046. The question is, will diabetic patients be willing to pay the additional cost for these lenses as opposed to low-cost pin sticks?
2) Drug Delivery Many researchers are working on creating drug delivery lenses and employing various strategies to overcome the primary obstacle: ensuring a constant release/dosage of the drug. It is beyond the scope of this article to describe these technologies in detail, but various methods in development include nanotechnology, embedding polymer films with drugs, molecular imprinting, and electrospinning. One group is creating a drug delivery lens in a dry state that becomes activated when hydrated. The military is very interested in that technology for use in battlefield situations.
The success of drug delivery lenses will be determined by the purposes for which they are used. Until extended wear success is improved significantly, placing a drug delivery lens for days or weeks at a time on an already compromised eye may not be successful. The shorter the duration of use, the less likely that there will be unintended complications. Short-term use for microbial keratitis or one-day drug delivery lenses for dry eye or allergy patients may have a better probability for success.
3) Myopia Control There is probably more interest in myopia control than in any other future contact lens technology, and there is probably no lens technology that has a greater potential to increase the number of contact lens wearers. Although no lenses are FDA-cleared for myopia control at this time, many practitioners are employing lenses off-label for that purpose. Orthokeratology and some distance-center multifocals have generated reports of some short-term success (Hiraoka et al, 2012; Sankaridurg et at, 2011). Certainly, within the next 30 years, there should be some conclusive evidence as to the effectiveness of using contact lenses for myopia control.
However, other strategies may supplement the use of contact lenses for this purpose. Atropine use at various concentrations has demonstrated lower rates of myopia progression than have contact lenses (Chia et al, 2014). It is conceivable that by 2046, gene therapy may be available to prevent the increase of myopia, or perhaps a combination of drug therapy and contact lenses may be employed.
4) Corneal Repair The health of the cornea relies on limbal stem cells to replace corneal epithelial cells on a regular basis. A reduction in the number of limbal stem cells can lead to limbal stem cell deficiency (LSCD). Trying to reconstitute the corneal surface with a synthetic or animal product may cause an unwanted immune response.
Researchers at the University of New South Wales have found a way of cultivating a patient’s own stem cells on the concave surface of a contact lens (Bobba et al, 2015). The study used lotrafilcon A silicone hydrogel lenses and the patient’s own blood serum (mixed with a cell culture medium and some antibiotics) as a substrate on the concave lens surface. Limbal stem cells are taken from the superior limbus or superior fornix. It takes up to 16 days for the limbal cells to colonize and cover the concave surface of the lens, at which time it can be transferred to the patient’s eye (after removing any scar tissue).
In a review that followed the outcomes of 16 patients who underwent this procedure between about one and six years ago, the success rate was 67%. Success was determined by improvement of ocular surface stability (restoration of transparent cornea, no neovascularization, and/or no recurrent or persistent epithelial defects) and visual acuity. The rate of success varied with the underlying LSCD etiology—iatrogenic causes had the highest rate of success, and those with chemical burns had the lowest rate of success. This technology has huge implications for patients who have LSCD and will hopefully be available sooner than in 30 years.
5) Low Vision Correction For those patients who have age-related macular degeneration (AMD) or other reasons for central vision reduction, telescopic glasses are cumbersome, cosmetically unappealing, difficult to use, and offer a limited field of view. Research teams in the United States and Switzerland have been working on a telescopic contact lens (Figure 3) that can switch between normal and telescopic magnification. The distance vision prescription is in the central 2.2mm aperture and is surrounded by a concentric telescope with a magnification of 2.8x. Switching between the two options will be accomplished by wearing polarized, 3D glasses and winking—wink with the OD for magnification, and wink with the OS for normal distance vision. Ordinary blinking will not create any change. The lens prototype is manufactured in polymethyl methacrylate (PMMA), but a new design is being created using a high-Dk GP material. The telescopic lens is not ready for human trials but has interesting implications for 2046, especially as the incidence of AMD is expected to rise with the aging of the baby boomers.
Figure 3. Telescopic lens for low vision.
6) Augmented Reality The most futuristic of contact lens applications is not far from becoming a reality. Many groups are working on contact lens technologies that will change how we view information. As opposed to virtual reality in which a person’s own field of view is supplanted with the virtual view, augmented reality overlays information on the normal field of view (remember the Terminator?) (Figure 4). The information is projected in front of the eyes, not at the plane of the contact lens.
Figure 4. Simulated view through augmented reality contact lenses.
Many uses for this technology have been envisioned (including one suggestion in which language translation can occur when someone is talking to you in a language that you do not speak). The gaming industry, the military, the travel industry, manufacturers, and others have an interest in this technology, which has the potential to result in a multi-billion-dollar industry.
Several key obstacles need to be overcome. To start, manufacturing such lenses needs to be cost effective. Another consideration is lens rotation. Will a toric lens type of design be needed to keep the display correctly aligned? Ensuring that the electronics, LEDs, power sources, etc., do not negatively impact the eye will have to be demonstrated. The potential decrease in the amount of oxygen getting to the cornea will have to be evaluated. Ultimately, mainstream commercialization will be dependent on making the lenses available at a reasonable cost.
7) Other Future Developments Another development is the potential of a “night vision” contact lens that will utilize graphene photodetectors to sense the low and mid-range infrared spectrum.
Is it too futuristic to contemplate a contact lens that can record video? Apparently not—this past April, Sony applied for a patent for a contact lens that can record and store video.
Many of these “functional” contact lenses will need a power source. Some unique options are in development. A Swedish company has developed a biofuel cell that runs on the ascorbate and oxygen naturally present in tears. The power output is very small, but may be sufficient to power a small sensor.
A company in Irvine, CA has created an energy source for contact lens electronics by placing a micron-sized piezoelectric energy “harvester” in the lens that will obtain energy from eye movements and blinking. Both of these developments would eliminate the need for an external power source. The Irvine researchers are also working on a contact lens storage case that will recharge electronic contact lenses as well as transfer data from the lenses.
Some potentially disruptive technologies may negatively impact the future of contact lenses. Within the past few years, some genes have been identified that are associated with the development of myopia. Although it will be many years before gene therapy is available, it is conceivable that it will be utilized by 2046.
Two corneal inlays that improve near vision for presbyopes are now available. The manufacturer of a third type is seeking FDA approval as is a company making scleral implants to correct for presbyopia.
There are already apps for smart phones that allow a patient to do a vision exam. Is it possible that by 2046, smart phones will have apps that act as topographers and aberrometers that will allow for the empirical ordering of contact lenses? A company in Germany has developed a new silicone 3D printing technology that ultimately may be used to print contact lenses. All of these technologies could impact the need for contact lenses or the way in which they are distributed.
We are in the midst of the digital age and on the doorstep of the “Internet of Things.” Technological breakthroughs are occurring at an accelerated pace. There is no reason to think that new technological advances won’t be made with contact lenses. Once the challenges of incorporating electronics into contact lenses are overcome, I have no doubt that there will be many new applications for contact lenses.
In addition, if long-term myopia study results indicate the successful reduction in myopic progression; if biometric coatings can increase lens comfort; if new multifocal designs create an increase in successful wear; and if augmented reality applications are viable, contact lens use will significantly increase. With an ever-expanding population, a foreseeable reduction in dropouts as comfort issues are reduced, and an increase in unique reasons for wearing lenses, contact lenses have a bright future 30 years from now. CLS
The author would like to thank the following for providing their input: Dr. Arthur Back, Dr. Lyndon Jones, Dr. Donald Korb, Dr. Jerry Legerton, Dr. Phil Morgan, and Dr. Eric Papas.
This article is intended to introduce readers to emerging technologies of the future, but not to provide an exhaustive commentary on all such potential future products.
For references, please visit www.clspectrum.com/references and click on document #250.
Dr. Sylvan currently practices with an optometric group in Hamden, CT. He has been a frequent lecturer on contact lens topics, has been involved in numerous clinical investigations, was a consultant to several contact lens manufacturers, and served in professional relations roles with two contact lens companies.