As opticians, we have all heard of Edwin Land, the founder of the Polaroid Corporation and famous for the Polaroid camera, who made his first fortune in polarized sunglasses. But an interesting fact you may not know is that this genius was a Harvard dropout! Land developed sunglass lenses that remove glare from horizontally polarized light waves that bounce off flat surfaces such as water, snow or pavement. The majority of glare is from light waves traveling on a horizontal plane after reflecting off flat surfaces. His polarized filter only transmitted light waves traveling on a vertical plane while blocking the reflected waves traveling on a horizontal plane. Horizontally reflected waves of light are greatly intensified when reflected, and we experience them as disability glare. Disability glare measurably impairs vision, reducing the contrast of the retinal image and washing out detail and color.
I am a proponent of polarized lenses for their ability to minimize the effects of disability glare especially for daytime driving. Glare is a driving hazard, and the following experiment proves the point: Drivers’ reaction times and stopping distances have been investigated in an independent test, conducted by RLT Car World, a European company. A 12,000-watt lamp provided a simulation of the sun’s glare. Drivers traveled at a constant 50 km per hour toward the “sun.” A hazard—a baby’s pram—was suddenly introduced into the driver’s path. Each driver was instructed to apply the brake only when they could see the pram. The study compared the results for drivers wearing ordinary sunglasses and polarized sunglasses against the “control test”—no sunglasses at all. Stopping distances and reaction times were measured.
The test reveals that when faced with glare from the sun while driving, ordinary non-polarized sunglasses make it harder to see than no sunglasses at all. Drivers without polarized sunglasses take a longer time to react, resulting in a dangerously long brake-path distance before their vehicle comes to a standstill. Reaction times for drivers wearing polarized sunglasses are up to 20 percent quicker compared to driving without any sunglasses and up to 40 percent quicker than with ordinary sunglasses. Faster reactions mean that stopping distances are shorter—by up to 6 meters—compared to driving with non-polarized sunglasses, and as much as 3 meters shorter than driving without sunglasses. Wearing sunglasses with polarized lenses is proven to block disabling glare, significantly improving driving safety. The study revealed that by simply wearing polarized sunglasses, the driver’s vision improved, cutting reaction times dramatically and reducing the risk of accidents.
As with many things in life, disability glare becomes worse with age. Johannes J Vos Ph.D., writes: “The age-adapted version of the Stiles-Holladay disability glare equation accepted by CIE as a standard, shows that disability glare rapidly increases beyond the age of 60 years: It doubles around 70 and triples at 83; of course, with large individual variations. Calculations indicate that the visual handicap due to disability glare in traffic and many other situations may be much more pronounced in the aged than in the young adult.” So, thank you, Edward Land, for this amazing discovery. And thank you to pioneers in polarization like Younger Optics NuPolar lenses for advancing ophthalmic lens technology and Transitions XTRActive Polarized Next Generation for pioneering polarized photochromic lens technology.
• Deborah Kotob
Pro to Pro Director