Abstract
Myotonic dystrophy type 1 (DM1) is caused by CTG repeat expansion in the DMPK gene in chromosome 19q13.3. External ophthalmoplegia is a rare manifestation in DM1. We report a DM1 patient confirmed by the presence of 650 CTG triplet expansions in the DMPK gene and had limitation of adduction gaze bilaterally. Brain MRI showed bilateral medial rectus muscles atrophy. Our patient provides additional evidence of ocular motor muscle involvement in DM1.