An unusual case of congenital convergent convergent strabismus fixus.

Background: Convergent strabismus fixus is classified into congenital and acquired types; however, there are only a few detailed case reports of congenital convergent strabismus fixus. Here, we report a rare case of this condition in which the eyeball was shown by imaging diagnosis to be fixed with a hard cord-like material in the orbit. To our knowledge, there have been no previous reports of congenital convergent strabismus fixus caused by an abnormal cord-like material that was clearly identifiable by imaging.

Case Report: The patient was a 16 year old female who visited our department for consultation regarding restoration of normal appearance of her strabismus. She had undergone strabismus surgery at the age of 3 years, but a forced duction test was strongly positive in all directions, and the eyeball was not mobile at the time. The initial surgery performed was a tenotomy of the medial rectus muscle and inferior rectus muscle and resection of the lateral rectus muscle of the right eye. The eye position and eye movement remained unchanged after surgery. At this time, MRI of the orbital region was performed, and an abnormal cord-like material connecting the posterior eyeball to the orbital wall was detected in the orbit. The cord-like material was pulling strongly on the posterior eyeball, congenitally fixing the eye position internally.

Conclusion: We experienced a rare case in which a hard cord-like material in the orbit congenitally fixed the position of the eyeball. On MRI, the intensity of the cord-like material was clearly different from those of the muscle and nerve tissues. Considering the linearity of the cord-like material and the results of a forced duction test, the cord-like material probably consisted of fairly hard tissue, similar to bone.