My husband wears contact lens for aphakic bullous keratopathy and is getting pain now. Why?

Hello doctor,

For ten years, my husband has been successfully using an extended wear bandage contact lens (monthly wear) to control the pain of aphakic bullous keratopathy in one eye. About seven months ago, he had an episode of foreign body pain in the eye which the contact lens could not control. His optometrist changed the type of lens after remarking that the lens appeared tight. Although the painful sensations have decreased, they are still present with more of a sore feeling now. His ophthalmologist suggested that he discontinue the Azopt drops he had been using in case the preservative was causing some corneal toxicity. His eye pressure without the drops has read at 18 and 20 on separate occasions, but he does have corneal edema which may affect the measurement. He has had high pressure in that eye previously, but it was mostly lowered by Cyclodiode treatment some eight years ago. The consultant said he had left him on the Azopt drops just as a precaution. My query is that if the bandage lens has worked so well for pain management for 10 years is it possible that it can continue to work? And if the Azopt drops and their preservative had caused some toxic reaction seven months ago, could that still be causing him to feel the discomfort? His consultant suggested out that he could have the eye removed to control the pain, but as he has what he feels is some slight, useful vision in that eye, he does not want to take such a drastic and life-changing step. In fact, he wants to pursue the least invasive course of action to relieve the pain he is getting. I would appreciate any advice you could give as he is in quite a bit of pain.