Chronic progressive external ophthalmoplegia.

Two cases of chronic progressive external ophthalmoplegia were described. Both of them presented with progressive bilateral ptosis and gradual impairment of ocular mobility. One of the patients had abnormal cerebrospinal fluid protein level. Another patient had muscle biopsy which was compatible with mitochondrial myopathy. Other possible causes of chronic progressive external ophthalmoplegia had been excluded by appropriate investigations. Chronic progressive external ophthalmoplegia is now considered as one type of mitochondrial diseases. Missed diagnosis of this syndrome is common in clinical practice.