This study conducted using a driving simulator showed that a blue light-filtering toric IOL produced a significantly greater reduction in glare disability than a control ultra-violet (UV)-only filtering nontoric IOL and increased the ability of drivers to safely execute left turns in low-sun conditions. Although this study from the May issue of the Journal of Cataract & Refractive Surgery is clearly sponsored by Alcon Laboratories, Inc., the manufacturer of the IOLs used in the study, it is interesting nonetheless.
The authors conducted this study to evaluate whether the previously established benefit of blue light-filtering IOLs when driving in glare conditions is maintained in patients previously implanted with a blue light-filtering toric IOL.
Subjects were 33 patients, of whom 18 had a test IOL (blue light-filtering Acrysof Natural toric IOL, Models SN6ATT or Model SN60TT, Alcon) and 15 had a control IOL (UV-only filtering Acrysof IOL without astigmatic correction, model SA60AT, Alcon) implanted between January 2008 and April 2010. All of them had good visual acuity and a valid driver's license.
While wearing best spherocylindrical correction, they performed left-turn maneuvers in front of oncoming traffic in a driving simulator. Measures were repeated with a glare source simulating low-angle sun conditions.
The safety margin, defined as the time to collision minus the time taken to turn at an intersection with oncoming traffic, in the presence of glare was significantly greater in patients with test IOLs (mean 2.676 seconds ± 0.438 [SD]) than those with control IOLs (mean 2.179 ± 0.343 seconds), and glare susceptibility was significantly lower (P < 0.05). In no-glare and glare conditions, patients with test IOLs had significantly lower glare susceptibility than those with control IOLs.
The authors say that although the difference in safety margins may seem small, this amount of time is substantial in driving and functionally significant. They note that a driver who executes a left turn with too short of a temporal margin leaves less time/distance to respond to unpredictable events, such as an oncoming vehicle speeding up, a pedestrian stepping into the road, or an unexpected wet or icy patch.