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Lee and Kim: The Relationship Between Velocity of Early Exotropic Drift and Recurrence
Original Article
Journal of the Korean Ophthalmological Society

Journal of the Korean Ophthalmological Society 2012; 53(4): 572-576.

Published online: 17 April 2012

DOI: https://doi.org/10.3341/jkos.2012.53.4.572

The Relationship Between Velocity of Early Exotropic Drift and Recurrence

Ja Young Lee, MD, So Young Kim, MD

Department of Ophthalmology, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Korea.

Address reprint requests to So Young Kim, MD. Department of Ophthalmology, Soonchunhyang University Cheonan Hospital, #31 Suncheonhyang 6-gil, Dongnam-gu, Cheonan 330-721, Korea. Tel: 82-41-570-2260, Fax: 82-41-576-2262, ophdrkim@schch.ac.kr

Received 7 March 2011       Accepted 7 March 2012

Copyright © 2012 The Korean Ophthalmological Society

Abstract

Purpose

To evaluate the relationship between velocity of exotropic drift and recurrence after surgical correction of intermittent exotropia.

Methods

The medical records were retrospectively reviewed preoperatively and at the following postoperative time periods: 1 and 5 weeks and 3, 6, and 12 months. The monthly change in alignment velocity in patients who demonstrated tendencies of exotropic drift was measured. The correlation between each data point and the velocity of total period (from 1 week to 12 months) was analyzed. According to the best correlated velocity of the time period, the patients were divided into 2 groups, and the motor success rates were assessed. Each group was further divided into 3 subgroups (esotropia, orthophoria and exotropia) according to angle of deviation at 1 week, and motor success rates were assessed again.

Results

Exotropic drift tendency was exhibited in 113 patients (91.13%). The mean postoperative monthly change in alignment velocity of total period showed the highest correlation with 1 month (Pearson, r = 0.61). The 2 groups divided by 3.57 PD/M were not different in motor success rate. The group showing exotropia at 1 week and high exotropic drift velocity at 1 month had a low success rate (Mann-Whitney, p = 0.03).

Conclusions

The velocity of exotropic drift at postoperative 1 month best reflected the total velocity but did not influence the recurrence rate. Based on the results from the present study, patients with exotropia and high exotropic drift velocity at postoperative 1 month have a greater likelihood of recurrence compared to the others.

Keywords: Exotropic drift, Intermittent exotropia, Motor success rate

Figures and Tables

Table 1
Demographics and preoperative characteristics of the subjects with exotropic drift
jkos-53-572-i001

Values are presented as mean ± SD or number (%).

PD = prism diopter.

Table 2
The monthly change in alignment velocity from postoperative 1 week to 12 months after surgery in patients who demonstrated tendencies of exotropic drift
jkos-53-572-i002

The mean postoperative monthly change in alignment velocities between 1 week and 12 months after surgery was 0.51 ± 0.57 PD/M and highest correlated with postoperative 1-5 weeks (Pearson correlation coefficient r = 0.61, p < 0.01).

Values are represented as mean ± SD.

PD = prism diopter; M = month.

*p < 0.05.

Table 3
Motor success rate of groups divided 3 groups by alignment at postoperative 1 week and then subdivided by 3.57 PD/M velocity at postoperative 1-5 weeks
jkos-53-572-i003

Motor success rate was defined as ocular deviation within 10 PD of orthophoria at 12 months postoperatively. The group showing exotropia at 1 week and high exotropic drift velocities at postoperative 5 weeks had low success rate.

PD = prism diopter; M = month; ET = esotropia; XT = exotropia.

*p < 0.05, Fisher's exact test.

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