When purchasing your summertime shades, take note that there are basically three different options of sunglasses that you have to choose from: regular color tint, photochromic (or 'Transitions'), or polarized. The majority of the sunglasses you see in your local optical shop, or retail store come with regular color tint. They are nothing very serious or super special, but come with a plethora of different tints and of course UV protection.
Photochromic lenses - more popularly known as Transitions, due to the major manufacturer - are a combination of regular eyeglasses and sunglasses in one pair of glasses frames. They allow you to wear clear prescription (or non-prescription) lenses when indoors, and slowly fade to shaded lenses for your outdoor eye protection when you head outside. They are very popular, but are fairly expensive.
Your last central option for sunglasses this summer are: polarized lenses. To the naked eye, polarized lenses and regular color tint sunglasses look nearly identical. However, the production of the lens is quite different, and more complex. Polarized lenses, usually significantly more expensive than regular sunglasses, contain a special filter that helps block excess light and minimizes glare that is normally experienced.
If prescription sunglasses is what you're looking for, most optical stores allow you to simply add color tint to your prescription glasses - or even polarized or photochromic additions, should you wish to spend the extra money. Should you wish to invest in nice pair (or a few nice pairs) of clear, plano non-prescription sunglasses, you can do that as well. There are tons of places that sell sunglasses, especially so close to summer! You could even check out some of the best online optical stores. It might be worrisome at first whether the frames will fit, but one of the main reasons to try and order glasses online is the major difference in price! So, you can actually get quite a few new sunglasses that can last you through the summertime, and possibly even into next year!