You can get prescription polarized glasses from your Dr. They cost a little more but are worth it. Other than that there are some polarized glassed made to fit over you prescription glasses, I think they are called cocoons. Cocoons also make a clip on that attaches to you current glasses which are less hassle than the fit over glasses.

Cocoons Eyewear - Questions and Answers About Fit Over Sunglasses

Look under Products and check out the clip on.
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