Myopic Progression and Postoperative Exodrift in Patients with Intermittent Exotropia

ABSTRACT

PURPOSE: To investigate the relationship between myopic progression and exodrift after surgery in patients with intermittent exotropia (X[T]). METHODS: Eighty-five patients who underwent bilateral lateral rectus recession for X(T) and had a follow-up of more than 1 year were recruited for the present study. Progression of myopia was determined by measuring the difference in spherical equivalent of both eyes between the initial and final refraction divided by the total follow-up time per patient. Postoperative exodrift was calculated by subtracting the deviation at postoperative 6 weeks from the deviation at the last follow-up, and the deviation at postoperative day 1 from the deviation at postoperative 6 weeks. Linear regression was conducted to determine the relationship between postoperative exodrift and myopic progression. The risk factors for recurrence, defined as exodeviation of 10 prism diopters or more at the final examination, were also analyzed. RESULTS: Sixty-eight (80.0%) subjects showed myopic progression of -0.50 diopters or more, and 47 (55.3%) had recurrence of exotropia during the mean follow-up period of 37.9 months. Patients with myopic progression showed more exotropic drift after postoperative 6 weeks than the patients without myopic progression (p < 0.01). Immediate postoperative overcorrection, oblique dysfunction, and a short follow-up period were associated with a low recurrence, whereas preoperative angle of exodeviation, sensory status, and age at the time of surgery were not. CONCLUSIONS: In patients who underwent bilateral lateral rectus recession for X(T), a greater myopic progression was related with greater postoperative exodrift. As the development of myopia was observed to be axial in nature, the results from the present study raises the possibility that ocular elongation may reduce the effect of recession.