Optical Characterization of Hydrogel and Silicone Hydrogel Soft Contact Lenses

Contact lenses are biomaterials that have emerged as an alternative to glasses in correcting vision defects. In this study, Nesofilcon A (Hydrogel-Hy) and Delefilcon A (Silicone Hydrogel-SiHy) daily disposable soft contact lenses were optically examined using UV-visible light spectroscopy. Optical absorption and transmittance measurements of the lenses were taken with a UV-visible spectrophotometer, and their properties of blocking the harmful part of the radiation to the eye and transmitting the harmless part were investigated. From the absorption spectrum, it was seen that the Nesofilcon A lens absorbed ultraviolet light better. From the optical absorption coefficient spectra of Nesofilcon A and Delefilcon A lenses, the absorption edges were obtained as 386 and 325 nm, and the optical band gap values were 3.34 and 3.98 eV, respectively. Additionally, the refractive index profiles of the lenses were plotted. The refractive indices of the lenses at 550 nm wavelength were calculated as 1.55 and 1.77 for Nesofilcon A and Delefilcon A, respectively. While the Delefilcon A lens transmitted visible light well, the Nesofilcon A lens blocked UV light better and its refractive index was determined to be closer to the 1.40 the value specified by the manufacturer.