You could make two incisions and compare the healing side by side, but It wouldn’t even take that all it would take is a plastic surgeon to preform a scar revision on an area like the chest, face or even on a cleft lip using verteporfin as these areas are prone to scarring regardless of healing ability, and if the fully healed result is clearly better or even 100% better then verteporfin is the culprit and definitely something to look into.