Well since I really can't tell what your dealing with he best suggestion I have is clean out you tank. I mean meticulously. I use a 1 to (1 part bleach to 10 parts water solution) of bleach to disenfect my tanks (scrubbing the sides with a clean washrag). RINSE ALOT. I can't say that enough. Rinse repeat, repeat etc. Get rid of the sand completly, aside from being abrasive--which might have led to the eye issue, it can harbor ALOT of bacteria and littly nasty germies. Replace the bed litter with Bed-a-Beast (should be available in a brick at your local petstore) but at this point even wet dow newspaper (black, no color) would be better than the sand.
Do more research on you froggie, find out his humidity and heat needs as well as tank size, change as needed.
As for the eye, I would need to see it to help, Its possible he's got a nasty eye infection. If you have taken him to a reptile vet they should be able to perscribe some to or anti biotic to help clear this. They will need to culture the eye (sample swap it) and look under a microscope to find out what kind of bacteria it is your dealing with. I have heard tetracycline works wonders, but only use this after you have gone to a vet to determine the real problem.
I work in a exotic vet office, e-mail me if you need any more advice, I can ask my doctor.