Surgical Outcome of Sensory Exotropia with Distant-Near Disparity

Abstract

Purpose:To assess clinical features of sensory exotropia with distant-near disparity, surgical outcome, and compare according to amount of medical rectus resection. Methods: Authors retrospectively reviewed medical records of patients of sensory exotropia with follow-up over 6 months. We defined patients with over 10 prism diopter (PD) disparity as distant-near disparity sensory exotropia (DND-XT) and without disparity as basic sensory exotropia (B-XT). First, we analyzed and compared data of visual acuity, cause and age of visual loss, amount of deviation. Second, Surgical failure was analyzed with dividing DND-XT into conventional surgery group as Parks' formula and reduced medial rectus resection group in accordance with disparity. Surgical success was defined as less than 10 PD deviation in distant, near fixation. Results: B-XT consisted of 58 patients (40 males) and DND-XT of 33 patient (13 males). There was no significant difference between 2 groups in onset and cause of visual loss, deviation at distant fixation. But, log MAR visual acuity of worse eye was better in DND-XT than B-XT (1.74 ± 0.78, vs. 2.10 ± 0.74, p = 0.039). Average deviation in distant fixation in DND-XT was 46.55 ± 16.59 PD in distant and 14.93 ± 8.91 PD in near fixation. All patients underwent surgery of medial rectus resection and lateral rectus recession and average deviation was 6.83 ± 7.71 PD at distant fixation, 3.02 ± 0.69 PD at near fixation at last follow-up. Among 33 patients, 16 patients underwent conventional amount of surgery and 17 patients with reduced medial rectus resection. In patient with conventional surgery, 9 patients were surgical failure (8 patients of over-, 1 patient of under-correction) but in patient with reduced amount of resection, only 1 patient was under-correction. Conclusions: As a result of medial rectus resection and lateral rectus recession in DND-XT, more surgical failures due to over-correction were observed with conventional resection and higher surgical success was attained in consideration of disparity.