This procedure was first suggested for "minimal ptosis of 3-4 mm." However, since the amount of ptosis varies widely with the etiological factors, the true indication in any given case is not the amount of ptosis but the amount of levator action. Hence, unless there is at least 10 mm of levator action, this operation is contraindicated. Since the levator (except that part of the aponeurosis that is adherent to the tarsus) is not involved, the procedure has been simplified accordingly.
Fox SA. A Modified Fasanella-Servat Procedure for Ptosis. Arch Ophthalmol. 1975;93(8):639-640. doi:10.1001/archopht.1975.01010020607009