Terahertz-based system for dehydration analysis of hydrogel contact lenses

Abstract

The use of terahertz-based techniques has grown very fast since they are capable of performingevaluations at molecular level, being very suitable for the analysis of biological samples and bioma-terials such as those for contact lenses. These biomaterials are continuously evolving to enhancethe lens wearer’s comfort by improving their hydration state and surface wettability. Therefore, thisstudy examines a novel terahertz system for the assessment of the temporary in vitro dehydrationof hydrogel contact lenses, which provides a new index to assess their state of hydration. Severalconventional and silicone hydrogel contact lenses and lens care solutions were analysed. Traditionalmethods such as the gravimetric determination of water content and the measurement of the staticcontact angle were also carried out for the validation of the developed system. The dehydrationrate measurements of contact lenses obtained with the proposed system correlated with the valuesprovided by traditional methods. As a whole, conventional hydrogel contact lenses exhibited thelowest values for dehydration rate. The tests conducted on various solutions showed a correlationbetween the wetting action of the solution and the dehydration rate of the contact lens material.