AIM: To report a distinct and sporadic case of congenital fibrosis of the extraocular muscles(CFEOM).

METHODS:A case report.

RESULTS: A 3-year-old Chinese boy who presented with exotropia and ptosis was diagnosed with CFEOM. Abnormal optic nerves were depicted by fundus examination, neuroradiology and electrophysiology. Pathological study showed muscle fibers were atrophic degeneration.

CONCLUSION: Our case highlights that CFEOM may have abnormal optic nerve and nontypical eye movement. The pathological study could help to find out the muscle fibers' alterations.