Chapter 2: Contact Lenses: Current Designs and New Strategies Check Access

With at least 140 million contact lens wearers around the world, as estimated in 2013, and over 100 contact lens patents filed from 2000 to 2019, the contact lens market is continually growing with an ever-increasing number of patent applications. The common contact lens applications are vision correction, therapeutic treatment, and cosmetic alteration, with vision correction being the most common contact lens application. Compared to spectacle correction, contact lenses improve the quality of life for wearers, especially for those with medium to high refractive error. Contact lenses need to be comfortable, safe, provide clear and stable vision and be practical to handle (including insertion and removal, cleaning and maintenance) for a reasonable length of time and at a reasonable cost. It is important for contact lenses to meet user demands with minimal short-term or long-term physiological changes to the ocular surface. There is an emerging opportunity to expand the function of contact lenses, with applications such as medication delivery, therapeutic treatment for acute and chronic disease (including anti-myopia treatment), diagnosis and monitoring of diseases, and incorporation of smart technology or virtual reality. These demands determine different material specifications and parameters, while balancing material costs and reproducibility.