No way I would ever enucleate an eye that can see, on the basis of "comfort" and "convenience."
Agree. Only if the eye presents a risk to life, as in having a tumor that is not amenable to local or field treatment, could you justify enucleation. A blind eye is a different story.
This isn't really an ethical problem for the OP; enucleation isn't indicated. This is a social service problem for the patient and to some degree, his doctor.
I feel for you. I had a patient a few years ago in the shadow of our nation's Capitol building who was a mentally-******ed adult with a horrific central corneal ulcer. She was dumped on me by a lame optometrist late on a Friday afternoon. She had to be admitted due to her utter noncompliance with management as an outpatient (failed followup, failed medication compliance, family was worse than useless). The minute she was admitted, the nursing utilization reviewer was leaning on me for discharge, since she technically lacked a diagnosis for which they could expect to be paid (by Medicaid, no less), even though the reasons were obvious and documented. After me refusing to discharge her (I dragged my feet as long as possible), they convinced the patient to leave AMA by threatening to charge the family for her stay. Nice job, it worked, but it didn't help her eye any.
You can't solve all your patients' problems. From the tone of the OP, it sounds as if the patient isn't entirely committed to cure, which is always a problem, especially when money is a driver.
Don't do an enucleation if there is vision, period.
No matter what happens, this patient will need followup and pharmacologic therapy. His not wanting to comply shouldn't drive your recommendation for best care. Anyway, the demand for enucleation could be seen as irrational and induced by pain and stress of worry about costs.
If you think his vision is bad enough, counsel him well about PKP and be sure to tell him that he could lose the eye anyway or that his vision would not improve ever. Of course, he will need drops after PKP anyway. Document the attempt to treat with medications and the fact that this treatment has failed due to patient non-compliance. Document that vision loss will result if no treatment is done and that the next therapy that has the prospect of preserving remaining vision is surgery. Go from there.