Photochromic lenses, commonly known as transition lenses, automatically adjust their level of darkness in response to changes in ultraviolet (UV) light exposure. These lenses darken when exposed to sunlight and return to a clear state indoors. The integration of blue light filtering capabilities into these adaptive lenses has become a growing area of interest. Blue light filtering refers to the property of a lens material to selectively block or absorb a portion of the high-energy visible (HEV) blue light emitted from digital screens and artificial lighting.
The rationale behind combining these two functionalities stems from the increasing awareness of the potential effects of blue light exposure on eye health and sleep patterns, alongside the established convenience of photochromic lenses. Prolonged exposure to blue light, particularly from digital devices, is hypothesized to contribute to eye strain, digital eye fatigue, and disruption of the circadian rhythm. Photochromic lenses offer UV protection, mitigating the risk of sun-related eye damage, while the addition of blue light filtering provides further visual comfort in the digital age.