Did the vet find an actual abscess or an infection in her mouth?
If he didn't, and is guessing, it's time to find another vet.
Several things can caused an eye to swell like that. Many times, it is an infection of the lacrimal duct. The duct can be plugged or it can be infected. The lacrimal fluid cannot drain into the mouth and eye swells up. If no infection is present, it is usually clear. Either way, the pressure of the swelling is very uncomfortable for the animal.
Sometimes irrigating it can help, and real reptile vets are taught how to manually drain them.
If the ducts are plugged or swollen due to irritation, antibiotics may be not help relieve the primary cause and will only stave off a secondary infection. It is therefore critical that the vet identifies the problem rather than prescribes an antibiotic that only relieve the swelling in your bank account.