Session: Poster session B

 Comparison of the surgical outcomes between Primary and Recurrent Intermittent Exotropia of 20 Prism Diopters

Introduction:

To compare the characteristics and postoperative surgical outcomes for primary and recurrent 20 prism diopters (PD) intermittent exotropia  

Method:

We retrospectively analyzed the medical records of 20PD intermittent exotropia patient who corrective surgery from Jan 2016 to Dec 2022.  And divided into two groups, the primary 20PD group(Group A) maintained good alignment  after primary surgery and the recurrent 20PD group(Group B) underwent secondary surgery for recurrence after an initial operation until at least postoperative 3 year in both groups.  We evaluated VA, cycloplegic refraction, Titmus or Worth 4-dot test, and prism alternate cover testing were performed pre- and at  POD 1 day, 1 wk, 1 mo, 3 mos, 6 mos, 1 yr, 2 yrs, and 3 yrs. Surgical success was defined as ocular deviation within 5PD of esotropia or up to 8PD of exotropia .

Results:

Total 103 patients were enrolled ( Group A: 80 , Group : 23).  The success rates at 1, 2, and 3 yrs postoperatively were 72.5%, 78.8%, and 70.0% for Group A and 69.5%, 56.5%, and 52.7% for Group B, respectively.  The immediate postop. correction effect per recession unit (PD/mm)was statistically higher in Group B than Group A (2.6 ± 0.7 PD, 2.2 ± 0.6 PD.p<0.05) at POD7day. The average overcorrection amount of the final successful group in each group at POD 1mo was  -3.2 -2.6 PD, while in the failure group was +1.0,+0.9PD. 

 Conclusion:

Even with the same amount of exodeviation, the postoperatively outcome for primary and recurrent 20PD inermittent exotropia is different. in the recurrent 20PD intermittent exotropia group, the surgical success outcome was poorer and  the immediate postop. correction effect PD/mm per recession was higher than primary. However, both groups showed a similar tendency for recurrence when rapid exodrift occurred 1mo after surgery.