Historically sports sunglasses brands do not offer prescription lens mainly due to the wrap-around shape makes fabrication of corrective lens very difficult.   With regular lens grinding technique, the lens essentially would fail to provide correct vision when wearer try to look to left or right and cause visual dizziness.

Contact lenses + sunglasses: Those who normally wear contact lens could choose to wear plano (without prescription) sunglasses, to achieve optical correction and sun protection.
Advantages: No limitation with choices of sunglasses on the market.  Recommended.
Disadvantages: Contact lens usage required careful hygienic preparation and maintenance.  Eye diseases patients such as trachoma would be prevent from using contact lens.

Sunglasses clip-on: This is a traditional method to add sun protection with existing prescription glasses.
Advantages: simple, direct, low cost, ease of use and removal of sunglasses clip-on to restore normal indoor condition.
Disadvantages: Limited clip-on styles and color choices, lack aesthetic, and the quality of workmanship cannot be guaranteed.

Prescription sunglasses: Only need to bring your prescription sunglasses when you are outdoor.
Advantages: a dual use, maintenance clear vision even without your normal reading glasses.
Disadvantages: You may often have to carry both pairs of glasses, unless you choose transition (photochromic) lens.

Choosing prescription sunglasses?