Nasa Vision Center saved the day AND saved me money! I've had a pair of prescription glasses with magnetic clip-on sunglasses for probably 20 years. I love the concept and ease of switching back and forth but over time the sunglass lens became scratched so I finally decided to go shopping for a whole new set. WOW! Prices sure have gone up! Since my prescription has changed just a slight amount one time thru the years I really only needed new sunglass lens. Thank you, Isabel, for mentioning you could replace the non-prescription sunglass lens for a very nominal fee. Problem solved and new shades are in the works. This is a very friendly vision center with a nice selection of stylish eyewear and easy in-out access.