You can buy prescription sunglasses or glasses with photochromic lenses (which change from clear to dark) from your eye care practitioner. Clip-ons may be a less expensive option, and can be bought at the same time as your regular eyeglasses to perfectly match the frames. Some eyeglass frames include sun lenses that magnetically attach to the frame. This gives you the convenience of clip-on sunglasses with less risk of scratching your prescription lenses.