Photochromic contact lenses: Optical analysis and visual effects of their transition dynamics.
Ruffato G., Kryeziu F., Sartoretto E., Gheller P., Rossetti A.
Since their introduction, the evolution of contact lenses has been mainly routed by criteria of wearing comfort, increased oxygen permeability, and correction of refractive errors, while less attention has been paid to the improvement of visual functions. More recently, a new type of contact lens has been designed and marketed containing photochromic additives that enable the filtering in the visible range depending on the intensity and spectrum of the environmental light. In this contribution, we have characterized the dynamics over time of commercial photochromic contact lenses in order to quantify their filtering effect in the visible as a function of the input wavelength and estimate the transition time necessary for their activation and deactivation. In addition, we have compared the influence of photochromic contact lenses $vs.$ standard non-photochromic control lenses on visual functions during specific indoor and outdoor activities. The present research encompasses an optical characterization of the constituent photosensitive material and an investigation of the expected visual benefits provided by the use of this new type of optical devices.