Polyester is plastic, so your skin is absorbing microplastics in the sun, you're breathing in microplastics, it also blocks sunlight, whereas cotton does not.

https://www.youtube.com/watch?v=02zFXhHqepU

When you wear sunglasses/eye-lenses/glasses you block indirect sunlight coming into your eyes. If you have to read, you have to read, otherwise, you can take your glasses off and never wear sunglasses.

Sunglasses just block UV and distort the spectrum. UV is the key thing you need, so you don't want to block it.