In invited commentary on a comparative study of the protective properties of windshields and side-windows in cars against harmful UV rays, Dr. Jayne Weiss, Professor and Chair of Ophthalmology at LSU Health New Orleans School of Medicine, has a take-home message for both ophthalmologists and consumers – UV protection should be used not just outdoors, but inside cars, too. Her editorial, UV-A Protection from Auto Glass, Cataracts, and the Ophthalmologist, was published online May 12, 2016, in JAMA Ophthalmology, available athttp://archopht.
“While windshields provide excellent protection against UV light, which is associated with risk for skin cancer and cataracts, side windows do not provide as much UV blockage,” notes Dr. Weiss, who is also the Director of the LSU Eye Center.
She cites a study demonstrating that a left-sided skin cancer was more common in those with skin cancer who spent more time driving and another study reporting a 93% reduction in cell death in the skin when UV exposure was filtered through UV-absorbing auto glass.
She reports that the differences in UV-A absorption between front and side windows are well known in the auto industry. UV-A rays, though weaker than UV-B rays, are the ones associated with longer-term skin damage, skin cancer, and cataracts.
Although front windshields are regulated by law to be made of laminated glass, which confers a Sun Protection Factor (SPF) of approximately 50, there is no such requirement for side windows. There also appears to be considerable variation in side-window UV-A blockage by the manufacturer, model, and year – information that is not easily obtainable by the consumer.
Recommends Dr. Weiss, “Until every automobile window is made of laminated glass, it is helpful for ophthalmologists to inform their patients that eye and skin protection may be indicated not only when outside, but also when inside an automobile. Patients should be informed of the advantages of driving with the windows closed, particularly when it is a sunny day. The use of UV-A-blocking aftermarket films, some types of window tinting, and sunblock/sunglasses can enhance the amount of UV-A blockage from side windows.”
