First of all, I think something may be off with his other eye as well. It looks more bugged-out than it should be. This frog needs a vet ASAP; if I were you I'd call in an emergency appointment.
Melafix can be used on eye infections. It's a fish medication. BUT it has to be extremely diluted (we're talking like drops/gallons) and I'm not 100% sure what the correct ratio is as I have never had to do that before. Someone else more familiar with that should be able to tell you how much to use.
If you haven't already, put him in a hospital setup. That's just a tank with no bedding, only wet paper towels (which need to be changed daily or whenever they are soiled) and his water dish.
Also, can you post the answers to the questions in this sticky so we can help figure out if anything in particular caused the infection?
http://www.frogforum.net/pacman-frog...enclosure.html