This one issue in scripture about Paul’s thorn is the flesh, the nature of which is purposefully unknown, does not negate the doctrine and demonstration of God’s ability, willingness, and desire to heal his people of their maladies, diseases and sicknesses.
Paul’s particular situation was between him and God. Our situation is also between each of us and God. Many people in the Bible had to wait for the manifestation of their healing. Even if the thorn in the flesh was some sort of eye disease, we don’t know if he wasn’t healed at some point later. There may have been other issues involved that we don’t know or understand. A lot conjecture here. The REAL point of the passage is that God’s grace is sufficient when we are in adverse circumstances that we don’t understand.
Our greatest challenge is to believe in the goodness and love of God even during adverse circumstances and trust in his promises which Paul did. Waiting on God in faith, sometimes for a long time, is something all of us, in one way or the other, have to learn to do by his grace.
Isn't that what we have been saying all along!? We wait on God's timing and trust in His perfect will for us even when it may mean our "divine healing" will be in our glorified bodies with Him in heaven.