Two words: . And if the thought of that kind of torture isn't enough to send sunglasses flying off the shelves, there's also the fact that certain types of , a clouding of the eye's lens, and worsen vision overall. (Sorry, no evidence we need to wear those … yet.)

Shady Business — The Takeaway

The sun's can cause both short and long-term damage to the eyes Sheedy, J.E., Edlich, R.F. College of Optometry, Ohio State University, Columbus, Ohio, USA. Journal of the Long-Term Effects of Medical Implants, 2004;14(1):67-71.. The immediate effects are pretty obvious: a seriously painful around the eyes. But the long-term effects can be even more problematic. Eye diseases caused by sunlight are known as ophthalmohelioses (say what?!), and include cataracts, damage to the retina, and, eventually, macular degeneration — which all worsen eyesight in their own ways Coroneo, M. Department of Ophthalmology, University of New South Wales, Sydney, Australia. Eye & Contact Lens, 2011 Jul;37(4):214-24. Glickman, R.D. Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX. Eye & Contact Lens, 2011 Jul;37(4):196-205. Chalam, K.V., Khetpal, V., Rusovici, R., et al. Department of Ophthalmology, University of Florida-College of Medicine, Jacksonville, FL. Eye & Contact Lens, 2011 Jul;37(4):225-32.. Plus, that immediately noticed can result in some seriously scary problems — and sensitive skin around the eyes is especially .

But things get complicated when considering sun exposure at different times of the year. One study out of the UK found that Brits get only about ten percent of their lifetime UV exposure during winter months and 60 percent during the summer, and another study found that people in some climates may not actually get enough UV exposure during the winter for beneficial effects (like ) Diffey, B.L. Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne, UK. Journal of Cosmetic Dermatology, 2002 Oct;1(3):124-30. Sliney, D.H., Wengraitis, S. Laser/Optical Radiation Program, USA Center for Health Promotion and Preventive Medicine, Gunpowder, MD. Progress in Biophysics and Molecular Biology, 2006 Sep;92(1):150-60. Webb, A.R., Kline, L., Holick, M.F. Vitamin D, Skin, and Bone Research Laboratory, Boston University Medical School, MassachusettsThe Journal of Clinical Endocrinology and Metabolism, 1988 Aug;67(2):373-8.. But researchers in Australia found a substantial proportion of UV exposure occurs in the winter (in part, because people tend to skip protection during cooler months) Neale, R.E., Hamilton, A.R., Janda, M., et al. Cancer and Population Studies, Queensland Institute of Medical Research, Brisbane, Qld, Australia. Photochemistry & Photobiology, 2010 Mar-Apr;86(2):445-8.. It all comes down to location, location, location: Folks living far away from the equator (eh there, we're talkin' aboot you, Canadians) might not need to worry so much about sun protection during the winter, but much of the rest of the world (including almost all of the U.S., South, and Central America) probably should Thieden, E., Philipsen, P.A., Wulf, H.C. Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Bispebjerg Bakke 23, DK-2400 Copenhagen, Denmark. The British Journal of Dermatology, 2006 Jan;154(1):133-8.. A good indicator of UV exposure, regardless of climate? How much of a shadow someones casts — the longer the shadow, the less UV exposure Sliney, D.H., Wengraitis, S. Laser/Optical Radiation Program, USA Center for Health Promotion and Preventive Medicine, Gunpowder, MD. Progress in Biophysics and Molecular Biology, 2006 Sep;92(1):150-60..

But that leaves out one important point: No amount of sun exposure is "good" for eyes. While the some UV love to properly synthesize vitamin D, the eyes don't need sunlight for any specific reason. Whether it's only 10 percent of our lifetime UV exposure or more than half, being exposed to sunlight in the winter (and fall and spring) can contribute to worsening eyesight. Outdoor sports on a fresh blanket of snow (or ice) can up to , and (we're looking at you, skiers and snowboarders) also up exposure. on a pair of shades before purchasing to check for both UV-A and UV-B protection between 99 and 100 percent (anything less just won't block it!). And in this case, the bigger the better — larger lenses and wrap-around styles help block out more light than smaller ones Sheedy, J.E., Edlich, R.F. College of Optometry, Ohio State University, Columbus, Ohio, USA. Journal of the Long-Term Effects of Medical Implants, 2004;14(1):67-71..

The Tip

Throw on some extra-large year-round to protect eyes from UV damage. Even in off-peak sun seasons, those rays can do some damage.