Which side should I hold on?

[prescription glasses]

I usually need to wear contact lenses, recently, I recognize the importance of UV protection from the sunlight, so, I was planning to buy a pair of prescription sunglasses, my friends told me that wearing non-prescription sunglasses over contact lenses cannot provide enough UV protection, but my optician also told me that is it hard to fabricate if I choose plastic frames as my Rx is too strong! What can I do now?