  There is evidence for the effect of blue light on circadian cycle and ocular
pathologies. Moreover, the introduction of LED lamps has increased the presence
of blue light. In the last two years, many different blue blocking ophthalmic
lenses have been introduced. Due to the different effect of blue light on
ocular media and circadian rhythm, we have defined two indices that describe
the level of protection of the lenses towards the retina and the circadian
cycle under different lighting as for example daylight and tablet. These
indexes can help in individuating the right lens for ocular protection.
