Diplopia as the presenting feature of acute lymphoblastic leukemia.

Purpose: To report a rare case of acute lymphoblastic leukemia presenting with diplopia to an ophthalmologist.

Observations: A 29-year-old male patient presented to ophthalmology department with sudden onset of binocular diplopia in left gaze. Magnetic resonance imaging of brain and orbits revealed a thickened left medial rectus, with enhancement of right sixth nerve, bilateral third and fifth nerves.