Can you post a picture of him? A good head/eye shot would be great!
How is he set up? What is the substrate, how are you heating it, what are the temps, how do you measure them, is the humid hide on the warm or cold side, what does he eat and how often. Please give a good run-down of things, it could be husbandry related.
He may have stuck shed in his eye, you can try to GENTLY drop some water in it (watch his ears!) and GENTLY GENTLY GENTLY rub with a wet Q-Tip. Is there any discharge? How bad is the swelling?
Again, pics would really help.