Wearing sunglasses, even in the overcast or unclear conditions is advisable. They will shield your eyes and help prevent squinting and even development of crows feet. Sunglasses reduce the rate of evaporation of tears and helps keep your eyes moist and comfortable. They also help keep contact lenses from drying out and prevent windblown particles from getting inside your eyes and causing a corneal scratch.
Lenses need to be UV protective in order to protect your eyes from damage the sun can cause. The price however, as with many things, does not always determine quality. Lenses that block all blue light are commonly amber colored and make your surroundings look yellow or orange. The tint supposedly makes distant objects appear more distinct, especially in snow or haze.
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