There are many definitions that describe the level at which nail fungus has been cured. A clinical cure is a 100% visually clear nail. A mycological (i.e., fungus-oriented) cure is a negative KOH preparation (a test used to diagnose fungal infections) and a negative fungal culture. Therefore, nail fungus is determined completely cured if there is both a clinical and mycological cure.[1]
After treatment, the affected nail may appear normal. However, this does not rule out the possibility of a fungal infection. Thus, it is not uncommon for nail fungus to return after treatment. Moreover, if the fungal infection is severe enough, it may cause permanent damage to the nail, which results in the affected nail never returning to its original appearance.[1]