If your midlaner is being camped, it is because you are not putting enough pressure anywhere else
I play Ryze mid and I am extremely aggressive. I can only ward so much and I'm often camped or have to 1v2 my lane. I wouldn't mind this if the rest of my team utilized this information and used it to their advantage. I just played a game where their botlane support would gank mid with their jungler. I would try to waste their time as much as I could but when I look botlane they're not pushing or trying to kill their ADC. This happened repeatedly.
All I am trying to say is that when one lane absorbs some pressure, you MUST make use of the relief to push your own advantage. If you don't, you're simply asking to lose the game.