What is the ruling on performing ablution (wudu') when there is a cream on the face that prevents water from reaching it for 12 hours, based on a doctor's prescription?

If the face is afflicted with a skin disease and the doctor prescribes an ointment that must be applied to it, and water must not reach it for several hours, then in this case, the area of the ointment should be kept dry during ablution (wudu’). The rest of the face and other limbs should be washed, and tayammum (dry ablution) should be performed instead of washing the affected part of the face, until the need for applying the ointment is over.