Orbicularis Oculi Muscle From Patients With And Without Involutional Ptosis: Histologic And Genetic Analyses In Elderly Asian Patients.

1. Harold Choi
2. Shantha Amrith

National University Hospital, Singapore

Purpose
To determine if there is underlying mitochondrial myopathy in some patients diagnosed as involutional ptosis, we compared orbicularis oculi muscle from patients with and without ptosis, using histochemical and mtDNA analysis.

Methods
We designed a prospective case control study. Cases were 10 patients with ptosis who underwent correction surgery. Controls were 11 patients without ptosis, who had eyelid surgery for other reasons. Orbicularis oculi muscle was examined with standard muscle histochemistry; modified Gomori's trichrome (MGT), nicotinamide adenine dinucleotide (NADH), succinyl dehydrogenase (SDH), cytochrome C oxidase (COX) and Congo red. Genetic analysis was performed for deletions of mitochondrial DNA (mtDNA).

Results
The mean age of the group with ptosis was 67.6 years and that of the control group was 64.9 years. Inflammation, fibrosis, or amyloid was not present in the orbicularis of either ptosis or control group. There was no significant difference in ragged red fibers, NADH, SDH or COX staining patterns between ptosis and control groups. One out of 10 specimens in ptosis group and 1 out of 11 in control group showed deletion of mtDNA. Our study of orbicularis oculi muscle found no difference between patients with and without involutional ptosis.

Conclusions
We conclude that presence of ragged red fibers, subsarcolemmal NADH and SDH accentuation, and COX negative staining patterns in orbicularis muscle are not markers of underlying genetic mitochondrial myopathy, and may represent age related involutional changes.