Data from World Health Organization (WHO) states that there are 246 million people worldwide who are visually impaired, out of which 43% are due to uncorrected refractive errors. Vision corrective lenses include prescription eyeglasses and contact lenses. Compared to eyeglasses contact lenses are lightweight and virtually invisible. Furthermore there are certain non-standard visual impairments, i.e. non-myopia, hyperopia, astigmatism, which cannot be corrected by normal glasses Contact lenses remain an important part of the modern eye care and culture, and more than 85 million people worldwide wear contact lenses for corrective, cosmetic and therapeutic purposes.
Contact lenses can be broadly classified into two types: hard and soft contact lenses. The hard contact lenses had low oxygen permeability which led to unwanted clinical events such as corneal hypoxia and various types of edema. The quest for oxygen permeability led to the development of soft contact lenses. The main advantages of soft contact lenses are the increased oxygen permeability, lens wettability, and overall comfort.
Although contemporary commercially available thin soft contact lenses have good oxygen permeability and good comfort level, they are encountered with the problem of proteinaceous deposits onto the polymer matrix. Further increasing the water content to reduce the extent of protein deposition has so far been not feasible considering that hydrogels are in general mechanically weak and this would compromise their mechanical strength properties.
We here present a novel nanocellulose reinforced hydrogel material featured with a set of optical and mechanical properties that are highly suitable for ophthalmic applications.