The Outcomes of Horizontal Strabismus Surgery and Influencing Factors of the Surgical Success
Suchada Kampanartsanyakorn MD*, Thamanoon Surachatkumtonekul MD*, Dhaivadee Dulayajinda MD*, Mingkwan Jumroendararasmee MD*, Sasima Tongsae MSc*
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University
Objectives : To evaluate the surgical outcomes of horizontal strabismus and identify the influencing factors of
the surgical success.
Materials and Methods : The medical records of 304 patients who underwent their first strabismus surgery for
treatment of horizontal deviation at Siriraj Hospital were reviewed retrospectively from January 1998 to
December 2003. The main outcome measure for successful surgery was defined as eye deviation 10 prism
diopters or less at 6 weeks post-surgery. The outcomes of postoperative binocular function and visual acuity
improvement were also evaluated. The pre operative deviation, diagnosis, binocular function, visual acuity
and age were analyzed as influencing factors of surgical success. The patients were divided into two groups,
the first group was 6 years or less (161 cases) and the second group was older than 6 years (143 cases). The
statistical methods for analysis the data were Chi-square test, Mann-Whitney U test and Logistic regression.
Results : The follow- up period was from 3 to 12 months. 187 patients (61.5%) for esotropia and 117 patients
(38.5%) for exotropia were identified. Mean patientûs age was 10.5 + 10.2years(median6, min0.5, max53),
mean preoperative deviation was 44.9 + 16.6 prism diopters and mean VA was 20/30(no PL, 20/20). The
success rate was 62.0% for esotropia and 57.0% for exotropia. There was no statistical difference between the
two groups of diagnosis. The average final deviation postoperative in the success group was 6 + 4.9 prism
diopters. The comparison of difference visual acuity between pre and post-operation showed no statistical
significance but the presence of binocular vision was increased in number of patient by two times. The
complication rate was 0.7%(2/304), one case showed conjunctival wound dehiscence and the other had
globe perforation. Re-operative rate was 12.9%(39/304) after one year.
Conclusion : The surgical success rate of horizontal strabismus surgery was 60.2% and revealed no statisti-
cally significant improvement of visual acuity after surgery. The successful surgery was related to the age
younger than 6 years and preoperative deviation less than 30 degrees.
Keywords : Strabismus surgery, Success rate, Outcomes, Influencing factors
