If you have, or know someone who has, red-green colorblindness. This may be the most amazing technology, ever. Colorblindness correcting sunglasses. They say it can be a bit disconcerting to see some colors for the first time. I’ll bet. At a minimum of $400 they aren’t cheap either.
EnChroma Cx: Color Blindness Correcting Lens
Here is a testimonial on the glasses.