Defining Success in Ptosis Surgery: Outcome Heterogeneity and Priorities for Standardization.

Ptosis surgery aims to restore eyelid position, visual function, facial expression, and, in children, visual development. Yet reported success rates reflect how success is defined as much as what surgery achieves. Studies use different eyelid-height thresholds, symmetry criteria, composite definitions, and follow-up intervals, limiting comparison across procedures and patient populations. This narrative review examines outcome assessment after ptosis surgery across six domains: anatomical, functional, aesthetic, patient-reported, safety, and durability outcomes. Margin reflex distance 1 remains the dominant anatomical endpoint, but accepted postoperative values vary and are inconsistently combined with eyelid contour, symmetry, and crease position. Within the same cohort, adding contour and symmetry requirements can reduce the reported success rate. Dynamic function, frontalis compensation, lagophthalmos, and dry eye are also inconsistently defined or omitted, despite their clinical relevance and procedure-specific effects. Anatomical correction does not reliably predict patient-perceived benefit, and no validated ptosis-specific patient-reported outcome measure exists. In children, success depends on visual development, amblyopia prevention, and ocular surface safety rather than eyelid height alone. Most studies assess outcomes within six months, limiting evaluation of recurrence and durability. A core outcome set could improve comparability without imposing a single definition of success across all ptosis subtypes, procedures, and patient populations.