Debating the importance of blue light filtering

Blue light filtering intraocular lenses (IOLs) provide protection against potential blue light toxicity without significantly affecting clinical functioning of recipients, said James D. McCulley, MD, during a spotlight session on pseudophakic IOLs.

"The question is no longer whether to use a blue-light-filtering IOL, but which one to use," said Dr McCulley, professor and chairman of ophthalmology, University of Texas Southwestern Medical Center, USA. "There are now a number of blue light filtering IOLs on the market worldwide and more to be released and we will see all sorts of variations and permutations as the market develops."

However, in a follow-up presentation, Randall J. Olson, MD, concluded that further study is needed regarding various potential adverse effects of blue light filtering implants. Dr Olson is professor and chairman of ophthalmology, John A. Moran Eye Center, University of Utah, Salt Lake City, USA. He told attendees that the Age-Related Eye Disease Study (AREDS) has provided strong evidence that blue blocking is not clinically important.

Dr McCulley presented evidence from the peer-reviewed literature that he believes has sufficiently addressed the concerns about blue light filtering IOLs that were raised when the technology debuted. Those studies demonstrated blue light filtering IOLs do not significantly affect colour or night vision nor interfere with glaucoma testing. On the other hand, there is evidence the blue light filtering implant can improve contrast sensitivity and colour perception in some populations.

More recently, questions have emerged about adverse effects on circadian functioning. However, Dr McCulley said blue light filtering IOLs allow sufficient light transmission for melanopsin regulation that controls melatonin release and they more closely mimic the normal condition that the human eye has evolved to over billions of years compared with a violet filtering IOL.

Dr McCulley acknowledged that the touted benefit of blue-light-filtering IOLs - prevention of age-related macular degeneration - remains unproven. However, there is abundant evidence demonstrating blue light damages retinal cells and these implants may offer other benefits for the retina as there are data to show blue light filtering can prevent increased proliferation of uveal melanoma and inhibit VEGF production.

Dr Olson agreed that an effect on colour perception is only rarely an issue, but he believes that the effect of these implants on causing scotopic visual loss is real and requires further study to determine its clinical significance. Similarly, he holds the opinion that the blue light filtering IOLs may have a clinically important impact on the circadian cycle and that issue also deserves further study to determine its relevance.