To evaluate the Histopathologic results of levator muscle and its aponeurosis and to underestand the relation between the histology and factors that can affect response to levator surgery.

: This study is a retrospective comparative before- and after-study done in a university – based hospital from november 2014 to january 2019. All patients that had ptosis were included in the study. Exclusion criteria were any history of eyelid trauma or surgery, any aberrant nerve regeneration or follow up less than 3 months postoperatively. Patients underwent levator muscle resection ether under local or general anesthesia. Tissue specimens were sent for histopathology exam. Patient preoperative and postoperative data and their relation to the histology report was analyzed.

880 patients underwent ptosis surgery during 5 years from 2014 to 2019. 383 patients were excluded due to incomplete follow up or reoperation sooner than 3 months due to undercorrection. Of 497 patients, 344 pations had CP and 153 had AP. Postop-MRD-1, -MRD-2 and LF improved significantly in both groups. Improvement was significantly greater in the AP group (p value< 0.001) in improvement of levator function and MRD-1. There was a positive correlation between preop-MRD1, postop-MRD2, preop-LF and a negative correlation between postop-lid lag and lagophthalmus with percentage of striated muscle report on histology report.

Histopathology of the levator muscle and presence of abnormal fat levels can predict the future success and even recurrence of ptosis, and it may be helpful in making the patient understand the etiology of recurrence.