Abstract
Purpose :
In the primary position, the inferior oblique (IO) muscle causes excycloduction and elevation of the eye and also acts as an abductor. Thus, theoretically, the IO weakening procedure can cause an esotropic shift in the primary position. We performed this study to determine whether the IO muscle weakening procedure combined with exotropia surgery affects the surgical correction of exotropia.
Methods :
We retrospectively reviewed the medical records of 310 patients who had undergone exotropia-correcting surgery combined with IO weakening (group A, 64 patients) or without IO weakening (group B, 246) with a postoperative follow-up of 6 months or more. The main outcome measures were the postoperative mean angle of horizontal deviation, the success rate, and the overcorrection rate. Surgical success was defined as an alignment between 10 prism diopters (PD) of exodeviation and 5 PD of esodeviation.
Results :
The postoperative mean angles of exodeviation, throughout the follow-up period, did not significantly differ between the groups. Although the surgical success rate was higher in group B at postoperative 1 month (p = 0.035), there was no statistical difference between the 2 groups from postoperative 6 months. The final success rates were 56.3 and 51.6% (p = 0.509). The overcorrection rate was significantly higher in group A at postoperative 1, 6 and 24 months (p= 0.017, p=0.028, p=0.030, respectively); however, at the final follow-up, there was no overcorrection in either group.
Conclusions :
The overcorrection rate was higher in group A until postoperative 2 years, even though the mean angles of exodeviation and the success rates did not significantly differ between the 2 groups. Surgeons should be mindful of overcorrection when planning exotropia surgery combined with the IO weakening procedure.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.