Time Course Analysis of Visible and Ultraviolet Light Transmissivity in Two Photochromic lens Materials

Abstract

<p>Ultraviolet light comprises wavelengths with high energy values that can have an impact on human health, which is increasingly worrying the health sector. Therefore, self-tinting lenses have become an alternative for eye protection. However, the loss of transmissibility of these lenses may represent difficulties in visual perception in environments where the luminous flux is reduced. It is important to take into account the transmissibility capacity of the photochromic coatings of ophthalmic lenses, taking into account their capacity in both visible and ultraviolet light. The objective of the present study is to determine the time variation of visible and ultraviolet light transmissibility in photochromic lenses of CR39 and MR8 materials. A study in which photochromic lenses of two materials (Cr-39 and MR8) were exposed to light for a period of 9 months, was carried out by taking transmittance readings at the frequencies of 535nm and 365nm, both at the beginning and at the end of the measurements. As a conclusion it was obtained that the photochromic lenses of both materials present a variation in the transmittance of both wavelengths as a function of their time of use and exposure. However, the variations found in the comparison between the two types of lenses and not over time are considered significant.</p>