Contact Lens and Anterior Eye 44 (2021) 157–191 Available online 25 March 2021 1367-0484/© 2021 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved. BCLA CLEAR - Contact lens wettability, cleaning, disinfection and interactions with tears Mark Willcox a, *, Nancy Keir b , Vinod Maseedupally a , Simin Masoudi a , Alison McDermott c , Rabia Mobeen a , Christine Purslow d , Jacinto Santodomingo-Rubido e , Silvia Tavazzi f , Fabrizio Zeri f , Lyndon Jones g, h a School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia b CooperVision, Pleasanton, CA, USA c Applied Sciences, Northumbria University, Newcastle upon Tyne, Tyne and Wear, UK d SpaMedica, Bolton, Greater Manchester, UK e Menicon Co. Ltd, Naka-ku, Nagoya, Japan f Materials Science Department, University of Milano-Bicocca, Milan, Lombardy, Italy g Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada h Centre for Eye and Vision Research (CEVR), Hong Kong A R T I C L E INFO Keywords: Contact lens discomfort Contact lens materials Disinfection Tear flm Wettability ABSTRACT Contact lens materials have undergone signifcant changes over the past 20 years, particularly with respect to the introduction of silicone hydrogel materials. Whilst this development addressed hypoxic issues, other important areas relating to contact lens success, notably comfort, require further research. Contact lens wettability remains a crucially important part of biocompatibility. Contact lenses can be made more wettable by incorporation of surfactants into blister packs, internal wetting agents, surface treatments or care solutions. However, there remains no clear association between contact lens wettability and comfort, making it challenging to determine the potential for these approaches to be of signifcant clinical beneft. Most contact lenses are used on a daily wear, reusable basis, which requires them to be disinfected when not worn. The ideal disinfecting solution would also improve comfort during wear. However, balancing these requirements with other factors, including biocompatibility, remains a challenge. Soft lens materials invariably take up and subsequently release certain components of disinfecting solutions onto the ocular surface. This may affect tear flm stability and the normal ocular microbiome, and further research is needed in this area to determine whether this has any affect on comfort. Finally, contact lens materials sorb components of the tear flm, and these in- teractions are complex and may change the biochemistry of the tear flm, which in turn may affect their comfort. In conclusion, the interaction between lens materials, tear flm and disinfection solution plays an important role in the biocompatibility of lenses. However, the exact role and whether this can be altered to improve biocompatibility and comfort during wear remains debatable. This report summarises the best available evidence to examine this complex relationship and the opportunities for practitioners to enhance in-eye comfort of contemporary lenses, along with providing suggestions for areas of study that may provide further information on this topic. 1. Introduction Contact lenses are medical devices that are primarily used for the correction of ametropia. The vast majority of today’s market, which accounts for approximately US$9 billion worldwide, is made up of soft contact lenses (~90 %; Table 1), while rigid lenses make up the remainder [1,2]. Further information on different contact lens materials is given in the CLEAR Material Impact Report [3]. This report outlines various changes in polymer and surface chemistry of contact lenses and how these result in improved oxygen permeability, wettability and in- teractions with the tear flm. The report also discusses the use of dis- infecting solutions and how these interact with the lens materials. * Corresponding author. E-mail address: m.willcox@unsw.edu.au (M. Willcox). Contents lists available at ScienceDirect Contact Lens and Anterior Eye journal homepage: www.elsevier.com/locate/clae https://doi.org/10.1016/j.clae.2021.02.004