Dr. Clark is located in the Pentagon City mall, which has a metro stop so it's very convenient. I needed contacts and placed my order with them for a few boxes after my appointment (the office is next to a Lenscrafters, so I might have been buying them from there. I never had to go into the Lenscrafters though- there's a separate entrance). They did not have the contacts- Acuvue 2- in stock and I had to go back to pick them up, which was a bummer. They gave me a copy of my prescription, which I used to buy more contacts online later.
A few months later I went to Hour Eyes in the same mall to buy glasses but couldn't find my prescription. I walked into Dr. Clark's office and they gave me a new copy on the spot with no hassle.