Special Contact Lenses Can Help Avoid Car Accidents

Special Contact Lenses Can Help Avoid Car Accidents
By Paddy Kamen

Driving more slowly at night seems to make sense from a safety standpoint. But when you’re driving slowly because you can’t see properly then all bets are off.

A study published in Investigative Ophthalmology & Visual Science

[i](the official publication of the Association for Research in Vision and Ophthalmology) found that multifocal contact lens wearers, while driving slower, also had a reduced ability to recognize road hazards.

For the study, 11 adults aged 45-64 drove on a closed circuit driving track at night. Their performance was judged on five criteria: road sign recognition, hazard recognition and avoidance, the ability to stay in the correct lane, near target recognition, and the distance required to recognize standard street signs. Participants’ only experience with vision correction prior to the experiment was using reading glasses for near vision.

The study also found that multifocal contact lens wearers had to be much closer to road signs to detect them than did those wearing eyeglasses. Poor vision has serious implications for road safety because not reading signs from a safe distance may result in sudden, dangerous lane changes.

The fact that low light conditions appear to significantly alter safety in night driving for multifocal contact lens wearers and others on the road is a concern that hasn’t previously been recognized or addressed. The study’s lead author, Byoung Sun Chu, Ph.D, formerly of theSchoolofOptometry, Queensland University of Technology inBrisbane,Australia, points out that eyecare practitioners may need to rethink vision correction for those who drive long distances at night.

“One alternative is to prescribe multifocal contact lenses for daytime use and a different correction for driving at night,” notesChu.

Bausch + Lomb appears to be the only contact lens manufacturer that has responded to the needs of contact lens wearers who travel, live and work in low light conditions. Their PureVision® 2 HD contact lense is the latest lens specifically designed for crisp, clear everyday vision even in low light conditions. The unique lens design is optimized to help correct spherical aberration (an optical effect causing blurred vision, halos and glare) across the entire lens power range.

The number of people who would benefit from these lenses is not insignificant. StatisticsCanadanotes that Canadians drive approximately 15 million km each day between the hours ofmidnightand6 a.m., when visibility is lowest. And there are 640,000 truck drivers on the road every day, many of whom drive through the night. Glare and halos, which impede vision, limit a driver’s ability to visually detect road conditions or obstructions.

Another situation that may warrant the use of PureVision 2 HD contact lenses for effective vision is shift work. Nearly 30 per cent of all Canadians work shifts and almost 55 per cent of nurses work evening and night shifts where lighting conditions may be less than optimal for effective vision. Even ostensibly pleasurable activities like attending the movies can be negatively affected by glare and halos when individuals are wearing vision correction that doesn’t serve them well in low light conditions.

Bausch + Lomb commissioned a study on the effect of glare and halos, which was conducted by an independent market research firm, Market Probe: Europe. The study, titled Needs, Symptoms, Incidence, Global Eye Health Trends (NSIGHT), surveyed 3,800 spectacle and contact lens-corrected subjects, 15 to 65 years of age, from seven countries (China, Korea, Japan, France, Italy, United Kingdom and the U.S.) to better understand the eye-related symptoms that vision-corrected patients experience. The NSIGHT data provided valuable information on how often patients experience halos and glare and the degree to which they found them bothersome. 

About half of the spectacle and contact lens wearers surveyed reported suffering from the symptoms of halos (52 per cent and 56 per cent, respectively) and glare (47 per cent and 50 per cent, respectively) more than three times a week. More than four of five patients who experienced these symptoms found them bothersome (84 per cent and 89 per cent for halo and glare, respectively). These findings indicate that the severity of symptoms associated with halos and glare is sufficient to impact patient satisfaction with prescribed vision correction methods. Given how bothersome they found halos and glare, (90 per cent for halos, 91 per cent for glare) patients reported either having no solution to the problem or none that was satisfactory. Moreover, the same percentage of patients (89 per cent for halos, 87 per cent for glare) expressed an interest in an intervention that more adequately addressed these symptoms.

Dr. Jeff Mungar is an optometrist and contact lens fitter based inOakville, On. “Impaired vision in low light situations can be caused by a number of eye conditions, including halos and glares,” he says. “As the pupil dilates it throws light rays out of focus creating glare and halos as well as blurring.”

Mungar says that while aspherical lenses have been around for some time, he hasn’t found a product better than Bausch + Lomb’s PureVision 2 HD for low light conditions. “It corrects each Rx through the full range and so is more precise in eliminating the spherical aberration, resulting in crisp, clear vision. As just one example, I refit a woman who had been wearing a spherical disposable. While I couldn’t correct her to 20/20, she saw one line better on the chart because the spherical aberration was corrected. With this product we have reduced halos and glares along with excellent lens breathability and high levels of oxygen transmissibility. It’s a comfortable, moist, easy-to-use lens that not only improves vision but also leaves the wearer with healthy white eyes, devoid of strain. I recommend that eyecare professionals discuss vision in low-light situations with their patients to help ensure that appropriate solutions are identified for those experiencing halos and glare.”

The PureVision 2 HD is available for those who don’t require astigmatism correction. “If the patient has more than .75 units of astigmatism he or she needs an astigmatic corrective lens,” notes Mungar.

With the road safety implications of wearing regular contact lenses now understood, thanks to Dr. Chu’s study, one wonders if a massive public and professional education program is in order. Surely we would all have a lot to gain.

[i] The Effect of Presbyopic Vision Corrections on Nighttime Driving Performance, by Byoung Sun Chu, Joanne M. Wood, and Michael J. Collins, IOVS September 2010 51:4861-4866; published ahead of print April 7, 2010, doi. www.iovs.org.