PURPOSE: To quantitatively analyze morphological and functional alterations of the meibomian glands in eyes with marginal entropion and their changes after surgery. METHODS: Sixty eyes of 52 patients with marginal entropion and underwent meibography and interferometer were included. One-hundred and seventeen age- and sex-matched eyes with minimal to mild meibomian gland dysfunction (MGD) were recruited as control eyes. Meibomian gland loss (MGL) and lipid layer thickness (LLT) were compared between eyes with marginal entropion and control eyes. Subgroup analysis was performed according to the extent of entropion. MGL and average LLT at 1 and 5 months after surgery were compared with those of 20 eyes with marginal entropion followed without surgery. RESULTS: In eyes with marginal entropion, MGL was higher (27.7% vs. 12.8%, P = 0.014), and average LLT was thinner (64 nm vs. 86 nm, P = 0.005) than those in control eyes. MGL was higher in eyes with more extensive entropion (> 2/3 eyelid width) than in eyes with less extensive entropion (≤ 1/3 eyelid width) (40.5% vs. 13.2%, P = 0.001). Average LLT increased after surgery (97 nm at 1 month, P = 0.003; 75 nm at 5 months, P = 0.319), and thicker than that of eyes followed without surgery (97 nm vs. 66 nm, P = 0.046). MGLs after surgery remained unchanged from the preoperative MGL (all P > 0.7). CONCLUSION: Marginal entropion is associated with morphological and functional alterations of the meibomian glands. Functional improvement after entropion repair suggests that marginal entropion could cause or exacerbate MGD. Further studies are required to establish the role of entropion repair in managing MGD.