hallenge. The frontalis muscle and levator palpebrae superioris muscle （LPS） are the two major sources of

force for upper eyelid elevation. Centering on these two power sources， in the field of severe blepharoptosis treatment，surgical procedures such as frontalis muscle and its fascia suspension， frontalis muscle suspension with materials （synthetic or autologous/allogeneic materials）， levator aponeurosis-Müller’s muscle complex advancement and shortening （or combined with partial tarsectomy）， and conjoint fascial sheath （CFS） surgery have long been adopted by clinicians. However， there have always been controversies regarding their respective advantages and disadvantages as well as their indications. Different surgeons often make different choices based on their varying clinical experience and perspectives. It is precisely this divergence in the logic of different choices that leads to inconsistent decisions in specific clinical treatments， and results in uncertain and unstable treatment outcomes. To make the optimal choice and achieve the best results according to the characteristics of each clinical case， it is essential to understand the pathogenesis， be familiar with the anatomical physiology， clarify the characteristics and target indications of various surgical procedures， optimize the technical process of each procedure， and sort out the logic for surgical procedure selection.

Blepharoptosis, Frontalis muscle, Levator palpebrae superioris muscle, Combined fascial sheath （CFS）,

Bridge technique, Synthetic materials, Suspension surgery