I've had this happen to my dog before, some mean person dumped glass in my yard (we lived close to a bar back then). I of course rushed him to the vet, spent a bunch, and all they did was clean and bandage. He didnt even need antibiotics! althogh they did give him a antibiotic shot when he was there.(and it was a good chunk off his PAD). What i'm saying is vet isnt necesarily the only way. I now treat minor injuries at home, i have guaze, solutions, etc. DO NOT USE CREAMS. These aren't BAD, but aren't helpful to a cat either. Use guaze. Place gauze square over wound. Get guaze wrap, wrap up the gauze square. Get Guaze Tape. Completely cover gauze wrap with the tape- this keeps it sterile and dry and clean. It will heal best this way (and yes this is what the vet did). The biggest tip is keep it dry!
Clean it every couple of days (probably 2 days max).
If you can check your cats temperature, that would be a startto monitor infection.
For cleaning use peroxide or saline solution etc.
If hes acting normal- thats a great sign, dont worry.