We report a case of infraduction limitation improvement and orthotropia at primary position in a patient with traumatic isolated inferior rectus muscle rupture after immediate repair surgery of the ruptured muscle.

A 47-year-old man came to our emergency department complaining of right eyelid contusion and conjunctival laceration after trauma due to the metal part of a high pressure hose. Right hypertropia of 20 prism diopters was observed at primary gaze and right hypertropia of 30 prism diopters was observed at down gaze. The right eye showed a -4 infraduction limitation. We sutured the distal part of the ruptured inferior rectus muscle with surrounding tissue, including the Tenon's capsule and the part of the muscle stump, to its original insertion. Orthotropia at primary position and 8-prism-diopters of right hypertropia on down gaze was observed one day after surgery. At 40 days after surgery, the patient had orthotropia at primary position and 4-prism-diopter right hypertropia on down gaze. Infraduction limitation of the right eye improved to -1.

Immediate repair of complete traumatic isolated inferior rectus muscle rupture can correct the limitation of extraocular movement and achieve orthotropia at primary position.