title: Mitochondrial Changes in Aging Orbicularis Oculi Muscles: Histologic and Genetic Analyses in Elderly Asian Patients.
abstract: OBJECTIVE
  We aimed to determine whether there was underlying mitochondrial myopathy in some aging patients diagnosed with involutional ptosis. We compared orbicularis oculi muscle from patients with ptosis and patients with dermatochalasis without ptosis, using histochemical and mitochondrial DNA (mtDNA) analysis.
  
  
  METHODS
  This was a case-control study.
  
  
  METHODS
  We studied 10 patients with ptosis who underwent correction surgery, and 10 patients without ptosis, who had dermatochalasis surgery, all in 1 institution. Orbicularis oculi muscle was examined with standard muscle histochemistry; modified Gomori trichrome, nicotinamide adenine dinucleotide (NADH), succinyl dehydrogenase (SDH), cytochrome c oxidase (COX), and Congo red. Genetic analysis was performed for deletions of mtDNA.
  
  
  RESULTS
  The mean age of the group with ptosis was 67.6 years and that of the dermatochalasis group was 65.2 years. Inflammation, fibrosis, or amyloid was not present in the orbicularis of either ptosis or dermatochalasis group. There was no significant difference in ragged red fibers, NADH, SDH, or COX staining patterns between ptosis and dermatochalasis groups. One of 10 specimens in the ptosis group and 1 of 10 in the dermatochalasis group showed deletion of mtDNA.
  
  
  CONCLUSIONS
  Our study of orbicularis oculi muscle found no difference between patients with and without involutional ptosis. We conclude that the presence of ragged red fibers, subsarcolemmal NADH and SDH accentuation, and COX-negative staining patterns in orbicularis muscle could represent age-related involutional changes. The significance of deletion of mtDNA needs further investigation.
authors.affiliation: From the Departments of *Ophthalmology, †Pathology, and ‡Pediatrics, National University Hospital, Singapore, Singapore.
authors.forename: Harold
authors.initials: H
authors.lastname: Choi
authors.forename: Amanda
authors.initials: A
authors.lastname: Charlton
authors.forename: Stacey
authors.initials: S
authors.lastname: Tay
authors.forename: Gangadhara
authors.initials: G
authors.lastname: Sundar
authors.forename: Shantha
authors.initials: S
authors.lastname: Amrith