EyeWorld Asia-Pacific September 2011 Issue

September 2011 18 EW FEATURE AcrySof Natural lens may help ameliorate glare problems while driving P atients who receive the AcrySof Natural SN60AT (Alcon, Fort Worth, Texas, USA/Hünenberg, Switzerland) blue light-filtering lens are not only less susceptible to glare, but also experience fewer collisions with oncoming cars than those with traditional lenses, according to Robert D. Gray, PhD, senior lecturer, School of Sport and Exercise Science, University of Birmingham, England, UK. In the January issue of the Journal of Cataract and Refractive Surgery, investigators led by Dr. Gray compared the effects of glare on those who received the blue light-filtering lens to those with a comparable acrylic IOL with no blue light filter. This study was an outgrowth of an earlier one. “A few years ago in 2007 I did a study looking at the effect of glare on driving in general,” Dr. Gray said. “There has been a lot of anecdotal evidence— Blue light-filtering lens reduces accident risk in simulator by Maxine Lipner Senior EyeWorld Contributing Editor almost everyone has had an experience of driving into the sun and headlights where it interferes with driving.” After this study appeared, an Alcon representative contacted Dr. Gray to suggest that perhaps he could use the simulator approach to take a closer look at whether the blue light-filtering lenses would help to reduce the effect of glare on driving. Dr. Gray saw this request as likely motivated by the recent call for more functional tests of vision for things like intraocular lenses. “We want some tests that are more relevant to real life,” he said. “Driving is something that everyone does, and this is something that may have serious consequence for accidents.” Comparative study Included in the study were two groups each with 17 patients who were implanted with intraocular lenses. “The lenses were identical in every way except for the blue light chromophore in one group’s lens,” Dr. Gray said. After the patients were screened and deemed acceptable for Testing in a driving simulator showed that patients with blue light filtering lenses had an edge in glare conditions Source: Robert D. Gray, PhD Haike GUO, PhD Professor, Department of Ophthalmology, Guangdong Eye Institute, Guangdong General Hospital 106 Zhongshan Er Road, Guangzhou, PRChina Tel. no. +86-20-83844380 Fax no. +86-20-83844380 guohaike@medmail.com.cn I n this article, Dr. Gray and his co-workers compared the effects of glare on driving performance between patients who had implantation of a blue light-filtering acrylic intraocular lens (IOL) and those who had implantation of an acrylic IOL with no blue-light filter. Their results suggest that the use of blue light-filtering IOLs helps reduce the effects of glare and improves the driver’s ability to safely execute a left turn with oncoming traffic in the presence of glare simulating low-angle sun conditions. As the eye ages and cataract develops, the transmission of short wavelength blue light to the retina is reduced. Removing the protective crystalline lens and replacing it with a clear UV-blocking IOL allows a greater amount of blue and violet light to enter the eye. Blue light-filtering IOLs were introduced clinically in 1991 based on a suggestion that blocking some violet light in addition to UV-radiation might improve photoprotection without significantly compromising scotopic vision. The impetus for development of these IOLs was twofold: first, to reduce cyanopsia and second, to protect the retina from possible light-induced damage. There are several unresolved issues regarding the introduction of blue light- filtering IOLs with respect to their potential benefits and possible side effects. Benefits that have been suggested include protection against retinal damage due to blue light, with a possible role in preventing the development or exacerbation of age-related macular degeneration; improvement in contrast sensitivity and reduced glare under photopic and mesopic conditions; and reduction in disturbance of blue color vision. Possible side effects of these IOLs, including detrimental effects on color vision and scotopic sensitivity as well as interference with the sleep–wake cycle, have been cited. Although arguments remain theoretical, new clinical data more relevant to real life in the use of these IOLs is now being presented. Gray et al. took a detailed approach to provide strong evidence of the benefit of blue light-filtering IOLs in improving the driving performance of older drivers in the presence of glare and increasing the safety margin. The real-world benefit of this technology is presumably mediated by a stronger signal to detect approaching objects (motion-in-depth) as a result of a reduction in glare disability. After almost 20 years of use, roughly 25% of IOLs currently implanted worldwide are blue light-filtering lenses. Continued widespread use of these IOLs indicates that although animal and cell culture experiments provide valuable information, it is more important to show clinical evidence about the effects of blue light-filtering IOLs on real-world tasks. Editors’ note: Prof. Guo has no financial interests related to his comments. Views from Asia-Pacific the study, they went to the driving simulator. “There was a long phase of allowing them to get used to the driving simulator and get adapted to it,” Dr. Gray said. “One of the main goals there, especially with older drivers, was to prevent any kind of motion sickness.” The basic experiment involved making left turns in front of oncoming traffic. “The patients drove around an urban