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Blue-light-filtering IOLs protect RPE cells from photochemical damage
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Blue-light-filtering IOLs may protect the retina better than conventional ultraviolet radiation-absorbing lenses, an experimental study suggests. In tissue cultures, yellow IOLs protected against light-induced photochemical damage and inhibited production of vascular endothelial growth factor better than either UV-filtering or non-filtering IOLs, researchers said.
Yasuo Yanagi, MD, PhD, and colleagues at the University of Tokyo exposed samples of human retinal pigment epithelial (RPE) to white light filtered by either a blue-light-filtering IOL (YA60BB, Hoya) or a UV-filtering IOL (VA60BB, Hoya). The researchers also exposed a third set of RPE cells to the light without using a filter.
All RPE cells were laden with A2E, a lipofuscin fluorophore thought to mediate light-induced cell damage and vascular endothelial growth factor (VEGF) production after blue light exposure. The researchers evaluated whether blue-light-filtering IOLs could replicate the A2E-limiting effect of a naturally aged lens.
Previous studies suggested that A2E is overexposed to blue light after cataract surgery because the naturally yellowed crystalline lens is replaced with a clear IOL, the authors noted.
At 48 hours after exposure, RPE cell viability decreased to 28% among non-filtered samples and to 33% among UV-filtered cells. The blue-light-filtering IOL significantly improved cell survival, with 42% of RPE cells remaining viable, according to the study authors.
The researchers also found that the blue-light-filtering IOL had a "potent inhibitory effect" on VEGF production. Openly exposed RPE cells showed a 3.2-fold increase in VEGF upregulation, which was only slightly attenuated by the UV-filtering IOL. Cells in the blue-light-filtering IOL group had about a 2.5-fold increase in VEGF upregulation, significantly lower than the openly exposed cell samples (P < .01), according to the study.
"In addition to photoreceptor cell damage induced by UV light, the upregulated VEGF production in RPE cells may explain why cataract surgery increases the incidence of exudative [age-related macular degeneration]," the authors said.
The study is published in the September issue of the Journal of Cataract & Refractive Surgery.