Mechanisms involved in eyelid ptosis surgery by conjunctivomüllerectomy: a histopathological and clinical study

Conjunctivomüllerectomy is a well-established posterior approach for the surgical treatment of mild-to-moderate aponeurotic blepharoptosis with a positive 2.5% phenylephrine test, but the mechanisms by which it achieves adequate eyelid elevation remain incompletely understood. The aim of this study was to quantify the proportion of Müller's muscle present in surgical specimens, to evaluate the degree of chronic inflammation in the resected tissue, and to correlate these histological findings with postoperative clinical outcomes assessed by margin reflex distance 1 (MRD1).

A prospective, observational clinical study was conducted on fifteen eyes from fourteen consecutive patients (mean age 68.9±11.7 years) with aponeurotic blepharoptosis, preserved levator function and a positive 2.5% phenylephrine test, who underwent conjunctivomüllerectomy according to the modified Putterman technique. Surgical specimens were processed for histological and immunohistochemical analysis. The percentage of Müller's muscle was quantified using smooth muscle actin, desmin and h-caldesmon, and chronic inflammation was assessed by the maximum number of plasma cells per high-power field (CD138 and CD38). MRD1 was measured before and four weeks after surgery.

No Müller's muscle was identified in 33% of the specimens, while the mean proportion in the remaining samples was 29.7 ± 31.5%. Levator aponeurosis and skeletal muscle fibres were absent in all cases. Chronic inflammation was present in 87% of specimens. Mean MRD1 improved from 1.05 ± 0.58 mm preoperatively to 3.77±0.46 mm postoperatively (p<0.001). MRD1 improvement showed a weak negative correlation with the percentage of Müller's muscle and a weak positive correlation with the number of plasma cells per high-power field.

The amount of Müller's muscle resected does not appear to be the main determinant of clinical success after conjunctivomüllerectomy. Chronic conjunctival inflammation may play a role in postoperative eyelid elevation through wound contraction and posterior lamella shortening. Conjunctivomüllerectomy is an effective technique for aponeurotic blepharoptosis, with greater benefit in older patients and in milder degrees of ptosis.