There are many you glasses shops in Washingtonk like Classic Optical Center, Xspectical Eye Care Center, Helfgott & Fine Md and Washington Eye Specialists etc. You can go any shop that closes to you to buy thick frames glasses with prescription lenses. For me, i prefer to go Classic Optical Center which located at 1895 L Street NW, Washington, DC 20036. And here i find some reviews about Classic Optical Center at http://www.yelp.com/biz/classic-optical-center-washington. Hope it help you.
You can find many optical stores in Washington where you can get thick framed glasses with prescription. Like Apex Optical, you can there to have a look whether they have thick framed prescription glasses sold. The local optical store offer fashion eyeglasses mostly for young people. Thick framed glasses are very popular these days and I believe you can get prescription eyeglasses with thick frames from Apex Optical. But they are pretty expensive. If you want to get cheap thick framed prescription glasses, you should search them online, which are much cheaper than the local optical stores.