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 performing evaluations at molecular level, being very suitable for the analysis of biological samples and biomaterials such as those for contact lenses. These biomaterials are continuously evolving to enhance the lens wearer's comfort by improving their hydration state and surface wettability. Therefore, this study examines a novel terahertz system for the assessment of the temporary in vitro dehydration of hydrogel contact lenses, which provides a new index to assess their state of hydration. Several conventional and silicone hydrogel contact lenses and lens care solutions were analysed. Traditional methods such as the gravimetric determination of water content and the measurement of the static contact angle were also carried out for the validation of the developed system. The dehydration rate measurements of contact lenses obtained with the proposed system correlated with the values provided by traditional methods. As a whole, conventional hydrogel contact lenses exhibited the lowest values for dehydration rate. The tests conducted on various solutions showed a correlation between the wetting action of the solution and the dehydration rate of the contact lens material.

Influence of Selected Ophthalmic Fluids on the Wettability and Hydration of Hydrogel and Silicone Hydrogel Contact Lenses—In Vitro Study

“…The moment when the mass of the sample did not change for at least 5 min was assumed as the equilibrium state. The obtained results allowed calculating the equilibrium water content (EWC) of the tested samples using Equation (1) [51]:…”

Metrology and Measurement Systems

“…It was also proved that better colour rendering assures better vision without increasing amount of light [8], however for many years it has been known that PC LEDs do not assure high rendering of colours [7,9], especially in the long wave part of visible spectrum. For this reason multi-emitter tuneable LED sources has been researched in lighting technology for over decade [10,11]. Various algorithms for selecting chips were proposed so that the entire spectral match could be obtained for various phases of daylight [12][13][14].…”