Evidence weak for blue light-filtering IOLs
Other studies found no such differences. These studies, however, all used luminance values of at least 1 cd/m2, which means the subjects’ vision was at least partly mediated by cones rather than rods, Li and colleagues wrote.
Blue light can suppress melatonin, so some researchers have speculated that blue-filtering IOLs might affect sleep patterns. Studies on UV-only filtering IOLs show improvements in sleep patterns, perhaps because the procedure replaced yellow lenses. One study comparing patients implanted with UV-only filtering IOLs and blue-light filtering IOLs found improvements in sleep only for those with the UV-only filtering IOLs. Other similar studies have also found no differences.
Could blue light filtering lenses affect macular degeneration? It is difficult to design a study answering that question, Li et. al. wrote, because “it would be impossible to control for the cumulative exposure to such visible wavelengths before surgery.”
However, one small, observational study found increased fundus autofluorescence, a marker for geographic atrophy and neovascular age-related macular degeneration, in eyes implanted with UV-only filtering IOLs and not in eyes implanted with blue light-filtering IOLs. Li and colleagues noted measures of autofluorescence are influenced by the nature and density for a cataract before surgery and the absorbance properties of the IOL.
Another study found geographic atrophy progressed more slowly in eyes implanted with blue light-filtering IOLs. However, the study did not control for age, genetic background, and other confounding factors.
“In general, the quality of evidence informing the surgeon’s selection of IOLs on the basis of light transmittance properties is deficient,” Li and colleagues concluded.