Prolonged hard contact lens wear may cause Mueller muscle fibrosis

Blepharoptosis as a result of prolonged hard contact lens wear may be due to structural changes in Mueller muscle, according to one study.

Additionally, blepharoptosis may not just be caused by aponeurogenic changes from the repeated removal of the hard lenses. Furthermore, fatty degeneration of the levator aponeurosis and Mueller muscle may be involved in the development of involutional blepharoptosis.

Akihide Watanabe, MD, and colleagues analyzed histological data from 30 patients divided into 2 groups. Samples were taken from 15 patients with hard contact lens-induced bilateral blepharoptosis (group 1) and 15 elderly patients with bilateral involutional blepharoptosis (group 2). Samples “were fixed in buffered formalin 10% (pH 7.0) and embedded in paraffin, and 4 µm-thick sections were mounted on slip-covered glass slides,” according to the study.

The authors found manifested fibrosis in Mueller muscle and collagen fibers were more abundant in samples from group 1. Additionally, Mueller muscle layers were thicker in group 1 than in group 2. According to the authors, age was not a factor in the presence of fibrosis in Mueller muscle in patients with hard contact lens-induced blepharoptosis.

Mild to severe microscopic fatty degeneration in the aponeurosis was observed in group 2 samples. In eight of the 15 samples of group 2, fatty infiltration in Mueller muscle was noted. In group 1, fatty infiltration in Mueller muscle and the aponeurosis was slight, leading researchers to believe the relationship between Mueller muscle fibrosis and ptosis in the group may be due to “a loss in the ability of the muscle to contract.”

In all 30 patients, the authors said “levator resection produced good results” without postoperative complications.

The study is published in the American Journal of Ophthalmology.