I use a type of sunglesses for watersports, produced by Tribord-Decathlon and sold cheap at about 30 euro, they have an integrated but amovable back neck strap and velcro adjustment. I suppose they are a copy from a famous Oakley model.
I find very important as with strong light I had in the past side effects, I think also because not drinking properly before windsurfing and so during some stops, so I started see all white and blinking. Now when there is sun I always wear sunglasses in windsurf sessions, and drink a lot before during and after. Imho