I need prescription glasses now too, but what I've tried just to see if the colours work, is just putting the coloured glasses on over my existing glasses. Obviously it's not ideal, but it's at least letting me know if the coloured glasses are likely to work, before I spend a lot of money on a pair.
As an aside, you've just reminded me that I need prescription sunglasses and I've forgotten to ring the optician again 🙈