25th Anniversary Perspective
The Next 25 Years: The Future of Contact Lenses
By Lyndon Jones, FCOptom, PhD, FAAO, & Eric Papas, PhD, MCOptom, DipCL, FAAO
The contact lens and accessory products of tomorrow need to offer better performance—and probably other advantages—over the lenses of today. So if we glimpse 25 years into the future, what will the contact lenses that are discussed in Contact Lens Spectrum of 2036 look like?
Improving end-of-day comfort will continue to be the number-one interest for the contact lens market.
How? Lens materials will likely have differing bulk and surface properties, with highly specialized surfaces that are grafted or chemically applied to the underlying material (Thissen, 2010), or will use some form of embedded or release mechanism to allow wettable agents to migrate from the bulk material to the surface and into the tears (Winterton et al, 2007). We may see lenses whose back and front aspects have different characteristics in an effort to present different surfaces to the corneal epithelium and the palpebral conjunctiva.
Some materials may slowly release components into the tears that are missing from the eye such as specific lipids (Pitt et al, 2011) or anti-inflammatory agents that may help suppress any low-grade inflammation (Andrade-Vivero et al, 2007; Kim and Chauhan, 2008). Materials may be developed that release essential fatty acids (EFAs) onto the ocular surface, whose anti-inflammatory properties may be of value in managing dry eye (Rashid et al, 2008; Jones, 2009).
Advanced Optical Designs
Enhancements in engineering have resulted in lenses with much improved and reproducible optics from that of 20 years ago, and it is envisaged that this will continue.
A further major factor outside of discomfort associated with contact lens dropout is presbyopia. Many previously happy wearers are unable to accept the visual compromise associated with multiple optics (bifocal or multifocal) or based on monovision. While many designers are frustrated by the optical limitations involved with perceiving multiple retinal images simultaneously, it is clear that modern presbyopic lenses have improved on their predecessors.
Nevertheless, truly satisfactory performance would still seem to demand lenses that dynamically alter focus to provide crisp, stable optics, whatever the viewing distance. Despite some intriguing current patents, perhaps the most likely source of a breakthrough in this area will be in the electro-optics field. Miniaturization of control circuitry combined with new optical elements may allow lenses of the future to be active devices, responsive to wearers' visual needs. Apart from building a better bifocal, this kind of device at least theoretically might be made to function as part of an imaging system delivering visual stimuli that are generated by artificial means to the retina. This might be very appealing to candidates for so-called “bionic” eyes, while it offers the possibility of “virtual reality” for the larger population.
One further thought in this area is that active elements within the lens might be arranged to make changes that are intentionally visible to others, giving a whole new dimension to the concept of cosmetic contact lenses. Changing iris color to match an outfit or even one's mood might become quite the thing.
Refractive Error Control
Most parents, particularly those who are spectacle wearers themselves, worry about their children becoming myopic. Any contact lens device that could reduce myopia progression would have a large and ready potential market.
It has been demonstrated in several species that it is possible to interfere with the amount of ocular growth, and thus the degree of myopia, using purely optical means (Charman and Radhakrishnan, 2010; Sivak, 2008; and others, full list at www.clspectrum.com/references.asp). If it turns out that humans behave in the same way, specially designed lenses could be significantly “anti-myopic.” Contact lenses incorporating these principles are already in clinical trials (Anstice and Phillips, 2011; Sankaridurg et al, 2010). Should the outcomes be successful, future contact lenses may well become available as therapeutic, anti-myopia devices or perhaps with indications for prophylactic use to prevent the onset of myopia in the first place.
Currently, most believe the main routes to preventing infection in contact lens wear include prescribing single-use daily disposable lenses or care regimens that eliminate any pathogenic microorganisms from re-usable lenses prior to reapplication. However, patients using daily disposables may still get serious corneal infections (Dart et al, 2008), and in the past five years two lens care products have been withdrawn from the market due to poor efficacy (Chang et al, 2006; Joslin et al, 2007) despite passing regulatory requirements during the development and licensing phase.
A major source of infection relates to contamination of the lens and contact lens case (Hall and Jones, 2010; Szczotka-Flynn et al, 2006), which then act as vehicles to transfer bacteria to the ocular surface. Various attempts have already been made to produce an antimicrobial contact lens (Mathews et al, 2006; Zhu et al, 2008; and others) but, so far, nothing has been commercialized. While incorporating an agent into the lens that can prevent microbial contamination appears relatively straightforward, it is more challenging to deal effectively and continuously with the multitude of pathogens that invade the conjunctival sac while avoiding ocular toxicity and not impacting the normal ocular flora. Additionally, concerns exist relating to endotoxins that may be produced following bacterial death (Liang et al, 2007).
The continued development of lens materials and cases that prevent bacterial adhesion, along with lens care solutions with enhanced antimicrobial efficacy, is a given. However, it may transpire that the only “safe” solution is a daily disposable lens and/or a short-term disposable case that is thrown away before high levels of contamination occur.
One of the biggest opportunities for the development of “specialized” contact lenses relates to their use as drug delivery devices. The extended release of drugs to treat infective complications such as microbial keratitis would have great value, as these patients often require hospitalization during the early phase of treatment to ensure compliance with drop administration. A lens that would release high doses of the drug for three to four days with extended, slower release over the ensuing five to seven days would find an immediate place in clinical practice. Other examples include lenses that release anti-allergic and anti-inflammatory drugs; lenses that release epithelial growth factors for managing patients following PRK and those who have corneal abrasions; and extended release of steroids, NSAIDs, and anti-glaucoma drugs. Materials that could deliver anti-VEGF treatments would have a multi-billion dollar market and would help eliminate the intraocular injections currently used for administration.
Based on the rapidly expanding literature in this field and the level of interest, it appears to be just a matter of time before such devices become available.
Several recent reports describe contact lens-based methods to monitor intraocular pressure (IOP) (Bertsch et al, 2006; Leonardi et al, 2009; and others); one commercially available device (Sensimed Triggerfish) uses sophisticated strain-gauge technology to determine IOP, and several groups have published on the development of materials that can monitor glucose levels within the tear film (March et al, 2004; Domschke et al, 2006; and others). Published work has looked at using the tear film to monitor signs of cancer (Evans et al, 2001; de Freitas Campos et al, 2008). Contact lenses that could detect such small levels of biomarkers within the tear film would be invaluable. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #187.
Dr. Jones is director of the Centre for Contact Lens Research and a professor at the School of Optometry at the University of Waterloo. He has received research funding from Alcon, AMO, B+L, Ciba Vision, CooperVision, Johnson & Johnson, and Menicon. Associate Professor Papas is executive director of Research & Development and director of Post Graduate Studies, Brien Holden Vision Institute and Vision Cooperative Research Centre, and senior visiting fellow, School of Optometry & Vision Science, University of New South Wales, Sydney, Australia. He has received research funds from Ciba Vision, Alcon, AMO, and Allergan. You can reach him at firstname.lastname@example.org.