I thought I would share this as it may save a few hard earned quid......
Being of poor eyesight as well as my other shortcomings, I have been looking for some prescription sunglasses suitable for sailing. I found a good range accidentally the other day at a big new Tescos - wrap around polycarb lenses with prescription lenses behind them and the facility to strap them on. They were marked up at "£40 for the frames plus £80 for the lenses" but it turns out that because the lenses were clear they actually fall under their "buy the frames and get lenses for free". On top of that, the has a "25% off" sale. The end result was prescription sports sunglasses for £30 a pair (I was so happy I bought two!
).Nigel