Mitigating retinal damage and circadian rhythm modification by blue-blocking spectacles lenses: evaluation parameters

It is well established that short-wavelengths visible radiation has the potential to damage the retina and pigment epithelium and there is evidence for the effect of the same wavelengths on the circadian cycle. The introduction of LED lamps and digital devices has dramatically increased human exposure to blue light. In the last two years, a number of novel blue-blocking ophthalmic lenses entered into the market with the aim to protect human retina preserving also circadian cycle, but unfortunately, there is a lack of clarity in factory communication in explaining how this lens works and should be used and prescripted. It is not evident for ophthalmologists which is the best lens depending on the needs of the patients. Due to the different effect of the blue light on ocular media and circadian rhythm, we have defined new separate indexes that could describe the level of protection of the lenses towards the retina and the circadian cycle under different lighting sources, e.g. daylight and tablet. These indexes can help in individuating the right lens for ocular protection. We have measured these indexes for many blue blocking lenses available on the market, evaluating the effect under daylight and during the use of digital devices. We also have evaluated the effect of these lenses on chromatic discrimination.