Future of Optics: The ultimate contact lens

Twenty years ago, two of the most prominent contact lens (CL) researchers in the world (Professors Brien Holden and Debbie Sweeney) predicted what the ultimate CL would look like moving forward.¹ Sadly, Professor Holden, the most visionary CL researcher in the history of our profession, passed away in July 2015. When their article was written back in January 2000, the biggest news was the commercialisation of silicone hydrogel (SiHy) materials by Bausch + Lomb and CIBA-Vision just one year prior. Daily disposable lenses were in their relative infancy, having been launched in the mid-1990s, and there were around half the number of CL wearers globally compared to best estimates today (80 million vs 150 million). With the luxury of hindsight, it is now possible to assess how close their predictions were, while also attempting the same feat with a look forward to what the CL practitioner of today may expect to be fitting in 2040.

Checking past predictions

Their first prediction was the expansion of extended wear, driven by the development of SiHy materials. The desire for patients to be permanently visually corrected remains well known, and for many the option of refractive surgery provides this opportunity. However, many ametropes do not want a surgical option and Holden & Sweeney predicted that the 30-day continuous wear approval for the initial SiHy lenses would result in a substantial number of people opting for such a refractive correction.¹ They described the initial clinical results, showing elimination of hypoxia, improved convenience and reduced number of infections. How close were they on this prediction? Certainly, the elimination of hypoxia proved to be the case, with many studies showing that hypoxic complications are a thing of the past in the majority of patients wearing these materials.² However, overnight wear of SiHys has not resulted in a reduced risk of microbial keratitis, the rate being almost identical to that seen with overnight wear of hydrogel materials.³ Interestingly, data generated within the past 20 years shows SiHy materials appear to have a doubly increased rate of infiltrative keratitis when used on a daily wear reusable basis,⁴ for reasons that remain unknown. They were certainly correct about the large-scale adoption of SiHy materials, with their use now accounting for approximately 75% of all soft lens fittings globally.⁵ However, the vast majority of these fits are on a daily wear basis, with most markets showing <5% of patients being fit with extended-wear lenses, with this modality being almost exclusively fit in SiHy materials.⁵

Their next prediction discussed the ‘ultimate lens’, which was envisaged to be one that was worn for several months at a time, exhibited improved comfort and reduced symptoms of dryness, eliminated adverse responses, was truly ‘biocompatible’ and challenged spectacles as the first choice vision correction. Twenty years on we have not seen any approvals for lenses to be worn beyond a period of one month without removal and that seems unlikely to change. Comfort of SiHy materials (as a category) on both a daily disposable or reusable basis is, broadly speaking, similar to that seen with hydrogels,^6-8 with exceptions of course for individual patients, who may report enhanced comfort with certain lens materials. No lenses have yet eliminated all adverse responses and the expectation that this would be achieved with SiHy lenses largely failed due to various mechanical issues, that are greater with some higher modulus, stiffer SiHy materials than that seen with hydrogels.⁹ One factor that has reduced inflammatory complications is the adoption of daily disposable lenses, which account for approximately 45% of all soft lens fits globally.⁵ Replacing a lens daily results in a significantly reduced risk of inflammatory complications,⁴ by up to 12x in some studies.¹⁰

Biocompatibility has proved to be an interesting topic, with initial thoughts being that biocompatibility required the development of materials that fully resisted deposition of tear film components.¹¹ However, that position has evolved over the past two decades. The current, contemporary view is that materials which interact with the tear film in an ‘appropriate way’,^12,13 resisting some components and absorbing others may be more desirable. These points are discussed in a recent review of a long-standing material that takes up large amounts of lysozyme from the tear film.¹⁴ With respect to challenging spectacles, daily disposables may provide quality of life benefits over spectacles¹⁵ and can provide ocular comfort that is indistinguishable to that reported in both spectacle wearers and emmetropes.¹⁶

Their third prophecy has been realised: continued growth in the development and use of lenses for presbyopia and astigmatism, with significantly more wearers of both categories over the past 20 years and such lenses now being seen as mainstream rather than ‘specialist’ fits.⁵ Their final prediction related to the concept of ‘implantable contacts’ for permanent vision correction, which has, to-date, not occurred on a large scale with artificial materials but has been used in some conditions using allogenic stromal lenticules.^17,18

Were there any gaps in Professors Holden and Sweeney’s predictions for routine CL practice in 2020? Two obvious omissions are the resurgence of scleral lenses^19,20 and the growing use of both soft and rigid lenses for myopia control,^21,22 although it must be recognised that the early development of CL for myopia control was passionately driven by Professor Holden himself.^23,24

What next?

What of the future? What do we predict will be the big changes for the CL practitioner of 2040? This has been the topic of a number of reviews, which suggest a move beyond simple vision correction to opportunities for lenses to be used for ocular drug delivery, sensing of both ocular and systemic disease and the use of lenses for entertainment and other electronic means such as correction of presbyopia.^25-29 The events of 2020 have also provided a glimpse into some of the ways clinical practice itself may evolve over the next two decades, with advances in technology and software to support remote consultations and fitting.

Conclusion

Looking back 20 years provides an interesting perspective on where two prominent researchers predicted what the future of CLs would look like. The introduction of SiHy materials and daily disposable lenses at that time brought about huge changes in available options for the CL practitioner of the day, and indeed many current eye care practitioners will have never worked without these materials and modalities. Looking ahead another 20 years, will CL practice be recognisable? It is hard to predict the biggest changes, although in time it is likely there will be an expanded role for lenses used as diagnostics or treatment options. What the events of this year have demonstrated though, is that the future cannot always be predicted, and ultimately time will tell.

Lyndon Jones is professor at School of Optometry & Vision Science, University of Waterloo, and director at Centre for Ocular Research & Education (Core), University of Waterloo.

Karen Walsh is professional education team leader, Centre for Ocular Research & Education (Core), University of Waterloo.

Disclosures

In his capacity as a researcher and professor at Core and the University of Waterloo, Lyndon Jones has received funding or honoraria from the following companies: Alcon, Allergan, Contamac, CooperVision, GL Chemtec, Johnson & Johnson Vision, Lubris, Menicon, Nature’s Way, Novartis, Ophtecs, Oté, PS Therapy, Santen, Shire, SightGlass, Visioneering Technologies. He acts as a consultant and/or serves on an advisory board for Alcon, CooperVision, Johnson & Johnson Vision, Novartis and Ophtecs.

Karen Walsh has received honoraria from Alcon, CooperVision and Johnson & Johnson Vision.

References

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