Chronic progressive external ophthalmoplegia (CPEO) is a rare disorder characterized by a slowly progressing paralysis of the extraocular muscles, resulting in bilateral, symmetric, progressive ptosis, later followed by ophthalmoparesis. Kearns Sayre syndrome (KSS) is a related disorder characterized by the triad of onset of CPEO below 20 years of age, bilateral pigmentary retinopathy, and cardiac conduction defects, most commonly atrioventricular (AV) block. Patients with KSS may also show other clinical features, including cerebellar syndrome, high serum levels of protein, pyruvate and lactate, ataxia, clinical depression, seizures, hypogonadism, hearing loss, mental retardation, and parkinsonism. The first clinical sign is usually the ptosis, which is bilateral and symmetrical. CPEO progresses slowly, without any remission or exacerbation.