Myofibre abnormalities of orbicular muscle in malposition of the eyelid

Fifty-five cases of senile entropion and ectropion have been studied electron microscopically. In both senile entropion and ectropion significant ultrastructural abnormalities were found in the orbicular muscle fibres, such as a disruption of fibres, Z line streaming, rod formation, Z line duplication and cytoplasmic body formation. These alterations have been described only in neuromuscular disorders and systemic diseases affecting the skeletal muscles. Our observations have confirmed that these abnormalities are not specific signs of any given disease, they rather represent the ultrastructural background of impaired muscle function independently of the aetiology of the disease.