Glasses USA takes 50% off most items sitewide via coupon code "SPECIAL50". Even better, that same coupon code yields free shipping. You'll also get $20 cash back, usable on the next purchase you make within 12 months. That's tied with our mention from August as the best discount we've seen from Glasses USA. (We saw 50% off without the cashback three weeks ago.) Eligible items include single-vision lenses and frames from brands like Ralph Lauren, Jones NY, Lucky, and more. Frames marked "Premium" are excluded.