Strabismus in chronic progressive external ophthalmoplegia

Area of Science:

• Ophthalmology
• Genetics
• Neurology

Background:

• Chronic progressive external ophthalmoplegia (CPEO) is a mitochondrial disorder characterized by progressive paralysis of extraocular muscles.
• Mitochondrial DNA (mtDNA) deletions are a common genetic cause of CPEO.
• Understanding the ocular manifestations of CPEO is crucial for diagnosis and management.

Purpose of the Study:

• To investigate the specific patterns of strabismus and ophthalmoplegia in Asian patients with CPEO.
• To correlate these findings with confirmed mitochondrial DNA (mtDNA) deletions.

Main Methods:

• Analysis of 10 patients diagnosed with CPEO and confirmed mtDNA deletions.
• Ophthalmologic examinations including cover tests, duction, and version assessments.
• Genetic analysis using long-range PCR and sequencing to identify mtDNA deletion ranges.

Main Results:

• All patients exhibited ophthalmoplegia and ptosis.
• Symmetric ophthalmoplegia was observed in 90% of patients; asymmetric ophthalmoplegia occurred in 10%.
• Exotropia, with or without vertical deviation, was the predominant form of strabismus (89% of symmetric cases).
• Diplopia was reported by 50% of patients, often associated with vertical deviations.

Conclusions:

• Exotropia, with or without vertical deviation, is the most frequent strabismus pattern in Asian individuals with CPEO due to mtDNA deletions.
• Asymmetric ophthalmoplegia is an infrequent but possible presentation of CPEO.