I had the same problem as others with sunscreen and water spots drying on the lenses, after trying to kite without sunnies for a while, I bought a pair of good quality but cheap,high UV protection safety glasses from Bunnings ( 10 bucks .I put them on, made a mark where my pupil was with a marking pen, measured down from the top of the frame to the mark I just made. I applied masking tape to the lenses,then re-marked the pupil level on the masking tape. I made a 3-4mm wide slot 20 - 25 mm long at or just below this height using a power drill and file. I had protection from the overhead sun, splash protection from the water and best of all clear vision. Worked for me and I can still see well enough to type this