Key Points
• Chronic progressive external ophthalmoplegia is a common clinical manifestation of mitochondrial disease.
• Existing extra-ocular muscle MRI data in CPEO reports variable radiological findings.
• MRI confirmed EOM atrophy and characteristic signal changes in CPEO.
• EOM T2 was significantly elevated in CPEO and correlated negatively with ocular movements.
• EOM T2 represents a potential quantitative measure of disease severity in CPEO.