Blue light-filtering IOL technology affords benefits without downsides

April 16, 2005

Washington, DC &#8212 An international panel of clinicians and visual science researchers concur that there is profound existing evidence and continually accumulating data supporting the use of blue light-filtering IOL technology.

April 17 - Washington, DC - An international panel of clinicians and visual science researchers concur that there is profound existing evidence and continually accumulating data supporting the use of blue light-filtering IOL technology.

The roundtable discussion event was sponsored by Alcon Laboratories, manufacturer of the AcrySof Natural IOL, and featured the participation of John Marshall, PhD, Richard Braunstein, MD, Richard Packard, MD, Manfred Tetz, MD, and John Werner, PhD. The "invitation only" Saturday evening program was held at the Grand Hyatt Washington during the American Society of Cataract and Refractive Surgery meeting.

A recognized expert on the science of blue light and age-related macular degeneration (AMD), Dr. Marshall pointed out that the risk factors for AMD appear to be multifactorial and involve contributions of both genetics and the environment.

"Retinal cell aging is partly related to genetic factors that determine the rate of that process, but it can be accelerated by environmental stress, of which light radiation may be considered the worst form," he said.

Damage from light involves exposure to UV and manmade sources and can occur via two mechanisms. However, the most important of those involves chronic low level exposure, and relevant to that process, there is now evidence from preclinical studies to show that genetics can affect the potential for blue light phototoxicity.

Dr. Braunstein, Dr. Packard, and Dr. Tetz spoke from the surgeon's perspective. Dr. Braunstein pointed out that the current goals for cataract surgery in the contemporary era are to provide a safe procedure and restore visual function, but also to preserve vision, both with regard to minimizing the risk of postoperative opacification and, if possible, reducing the risk of AMD.

With respect to the latter, in vitro research from his Columbia University colleague Janet Sparrow, PhD, demonstrated that a blue light-filtering IOL can protect against blue light-induced apoptotic death of RPE cells co-cultured with A2E.

"I cannot guarantee to my patients that this IOL will protect their vision. However, they appreciate receiving this option providing that potential benefit with no downsides," Dr. Braunstein said.

Dr. Packard echoed the same sentiment.

"It appears that we have more than ample evidence from available studies to indicate this IOL technology affords a benefit not available with a traditional UV-blocking lens, and so it seems logical to offer our patients the potential for protection against AMD, particularly as we enter an era where refractive lens exchange procedures are being performed with increased frequency in generally younger patients," he said.

Since 2003, Dr. Packard reported implanting the blue light-filtering IOL in a single eye of 575 patients, of who 132 had a clear lens in the fellow eye, and bilaterally in 151. In that extensive experience, not a single "mixed pseudophakic" patient has ever mentioned noticing any color discrepancy, differences in vision between eyes, or difficulties with night vision, even including the subgroup of younger, refractive lens exchange patients.

Dr. Braunstein pointed out that nearly 2 million of the blue light-filtering IOLs have been implanted worldwide. In that vast experience, there are no reports in the literature or to the manufacturer of lens explanation because of low light or color vision problems.

"That is an exceedingly exceptional track record," he said.

That clinical experience is consistent with research Dr. Werner has conducted addressing the question of whether a blue light-filtering IOL would decrease the sensitivity of the rods and adversely affect visual function under scotopic conditions. Results from his studies support the conclusion that neither scotopic sensitivity nor more importantly scotopic contrast sensitivity would be affected to any measurable degree in patients implanted with a blue light-filtering versus a conventional IOL.

"Even in the worst case scenario of measurement at a 1.2 cycle per degree grating, the amount of light level reduction associated with implantation of the blue light-filtering IOL would only decrease contrast sensitivity by 0.01 log units, which is a trivial effect," he said.

Early experience with an investigational aspheric version of the blue light-filtering IOL is encouraging. Available data and anecdotal observations show so far that it significantly reduces spherical aberration compared with a conventional IOL and has been associated with very positive patient satisfaction, noted Dr. Braunstein.

Dr. Tetz reported implanting the wavefront version of the blue light-filtering IOL in 16 eyes of 10 patients. His initial analyses show its benefits for reducing spherical aberration compared with a spherical IOL.

"The AcrySof IOL represents one of the most modern and safety-proven platforms in IOL history, and the combination of the blue light filtering with an aspheric design is consistent with our surgical goals of protecting and improving visual function," he said.