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Weaknesses of Transitions Photochromic Lenses

27/10/2014

Photochromic lenses are those which darken when exposed to sunlight. Often referred to as "transitions lenses" this is in fact a reference to the largest retailer of photochromic lenses, Transitions Optical Inc. This revolutionary technology has enabled those who wear glasses to conveniently incorporate their spectacles and sunglasses into one set. According to All About Vision, photochromic lenses provide 100 percent protection against ultraviolet radiation.
Tint:
One limitation, according to J Kounnas Optometrists, is that photochromic lenses remain slightly tinted, even in areas of low lighting or at night time. However, it does also state that this should not reduce vision. To the contrary, All About Vision argues that the "tinted" character of photochromic lenses may benefit patients suffering from certain eye pathologies. It highlights the 'red' colored lenses developed by Corning CPF family, which are sometimes used to enhance the vision of patients suffering with molecular degeneration.
Defense Against UV Light:
Another disadvantage of photochromic lenses is that they may not darken if worn inside a vehicle. This is because the windscreen acts as a filter and absorbs the UV light, thus undermining the function of the photochromic lens. In days or situations of bright light, drivers may find themselves resorting to their "old-fashioned" sunglasses, for UV protection. In February 2009, Transitions Optical along with Younger Optics began seminars educating eye professionals about their new "Drivewear" lens, which combines polarization and photochromic technologies, enabling them to be worn while driving.
Delay:
Photochromic lenses do not transition from light to dark (and vice versa) automatically. Instead, J Kounnas Optometrists estimates a delay of 2 to 3 minutes, suggesting that this could be problematic during activities with rapidly alternating light. Cyclists or motorcyclists using photochromic lenses, for example, should take care when entering a tunnel.
Cost:
Due to their sophisticated technology, photochromic lenses are more expensive than their regular counterparts, which may make them unaffordable for some people. However, as Eye Doctor Guide notes, they save you the expense of purchasing an additional pair of sunglasses, so may be a cheaper option overall.