BUYING
In the outdoors, the use of sunglasses is neither a luxury nor a fashion statement, especially in places where the sun is strong and where objects seem to appear from nowhere.
Ultraviolet radiation (or UV rays) coming from the sun can damage the eye’s crystalline or retina and any other parts of the eye. This damage can sometimes be permanent.
In order to adequately protect your eyes against UV rays, make sure that the lens of your sunglasses offers at least minimum protection.
If you plan on using your sunglasses in all sorts of circumstances and under different lighting conditions, the best choice is photo chromic lenses (tint changing with the intensity of the light). This way, the lenses will be lighter under a shaded forest and darker when surrounded by water or snow.
Sea kayakers and skiers will get more benefit from polarized lenses which block direct sunlight, as well as the rays reflected by water or snow.
If you use your sunglasses mainly for water sports, you might want to consider floating frames.
To avoid fogging, it is important that the sunglasses be well ventilated and the frames not too close to the eye socket or the brow ridge. In contrast, the frames must lightly hug the eye socket so as to prevent the UV rays from reaching the eyes.
If you use your sunglasses mainly for water sports, you might want to consider floating frames.
Many outdoor activities can lead to potential eye injuries, for example, getting a tree branch right in the face during a run or a mountain bike ride, getting a piece of ice or break-stone in the eye when climbing, etc. In these cases, it would be best to wear sunglasses that offer greater protection and that are impact resistant.
If plastic sunglasses are of average quality, those made of polycarbonate are perfect for the outdoors. Not only are they light, but they provide excellent protection against UV rays and better resistance on impact than glass (even though they have a tendency to get scratched).
Glass is heavier, but allows for a better visual definition; as well it can be polarized. Its heavier weight, however, make it less appropriate for certain activities (running, kayaking, etc.). Glass can also break on impact.
USE
Make sure to get a hard case to protect your sunglasses during transportation.
If you participate in intense activities where you might lose your sunglasses (powder snow skiing, rafting, water skiing, etc.), buy a strap that will allow you secure your sunglasses to your head or neck.
Ideally, you should buy a pair of spare sunglasses, and leave them in your backpack during long walks or activities in remote wild areas. If you break or lose your sunglasses, you will be prepared.
MAINTENANCE
To remove fog or to clean lenses, always have a synthetic cloth on hand. Avoid using paper tissue as it leaves residue. Paper tissue is also harsh and could damage the surface of the lenses.
If fog remains in spite of good ventilation, apply an anti-fog product.
Always rinse your sunglasses with soft water when you have been in salt water. Salt water can damage the lenses in the long run, especially if they are polarized.
Wash the lenses of your sunglasses with dish detergent and warm water. This helps dissolve grease (from sun screen for example).
Finally, here is a good tip for all outdoor activities: always keep duct tape, even epoxy glue for a quick repair in the field.