Nice photos

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I always wear sunglasses (Seaspecs). I find they don't tend to fog up (especially with a bit of spit inside them, as for a dive mask) and the strap keeps them on my head quite securely.
I also use a helmet (Protec) which locks them on so they can't come off. It also provides a bit of sun protection, but not as much as a brimmed surf hat.
I use a grey lens is good for bright sunny days and a brown lens for winter, cloudy days, dawn or dusk.
I have a clear pair too but haven't used them much. The brown lens is good for nearly all low light conditions.
I really like the protection that glasses offer from spray too.
More info:
kitesurfing-handbook.peterskiteboarding.com/gear/sunglasses