If your dog develops an ulcer from the infection, or a scratch from rubbing the eye and you administer the wrong ointment, your dog could develop severe ulceration and lose the eye. I've seen it happen in 48 hours when owners didn't think it was a big deal.
The surgery to save a ruptured eye runs about $2500 and the surgery to remove a blind and worthless eye is about $600-1200 depending on your area.
Don't play Russian roulette with your dogs vision. It could be nothing or it could be REALLY serious.