If you want to wear the sunglasses for high altitude, you could wear the ray ban sunglasses with polarized function which will protect your eyes from the uv rays and other bad lights. The ray ban sunglasses have many designs which will make you look cool. The quality of this brand is durable which you could wear for many years. You could have a try and go to the real store to have a look.
Since you want to wear them in high altitude. I guess you need durable and light sunglasses which is extremely efficient in ultraviolet resistance. The sunglasses which is made of polycarbonate is exactly what you need.
The advantages of polycarbonate over resin sunglasses:
1. It is anti-ultraviolet. Nearly 100% ultraviolet can be shielded. It also won't change color, while resin lens tend to turn yellow overtime.
2.It is the lightest material for optical lens. It is 30% lighter than resin lens and 50% lighter than glass lens.
3.Polycarbonate is famous for being tough and unbreakable. It is often used as bullet-proof glass.
4.Polycarbonate lens has a high index, so it is much thinner than resin lens and glass lens.
All right, I can see that you are in need of a pair of good sunglasses to prevent your eyes from getting burned by the sun. Anyway, altitude means stronger sunshine and higher UV level. Therefore, you have to look for a pair of sunglasses with perfect UV protection and try to avoid looking at the sun directly. Just consult an optical professional for some advice and seek what you need.