Surgical Outcome Of Unilateral Lateral Rectus Recession For Treatment Of Intermittent Exotropia In Children

BACKGROUND AND OBJECTIVE:Intermittent exotropia is the most common form of divergent strabismus in children. Initially, the deviation is usually intermittent and children often have the ability to control the exodeviation. However, it may progress in amount and frequency, and surgery should be performed to restore ocular alignment in this situation. Bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession combined with medial rectus resection (R&R) are both the traditional treatment for intermittent exotropia. It's generally believed that an initial postoperative overcorrection of exotropia following bilateral lateral rectus recession is desirable for a better long-term alignment. However, the visual system of children is relatively immature, small persistent postoperative esotropia may result in a development of amblyopia and the risk of losing of bifixation. Unilateral lateral rectus recession has been successfully used for the treatment of intermittent exotropia in recent studies. However, there is a widely disagreement on the surgical effect of this procedure. Many surgeons avoided using this procedure concerning that it may result in a significant number of undercorrections and/or produce ocular incomitance. This study was undertaken to investigate the long-term surgical outcome of unilateral lateral rectus recession for small to moderate angle intermittent exotropia in children.METHODS:Sixty-nine children with intermittent exotropia (15-35 PD) who underwent unilateral lateral rectus recession from April 2009 to March 2010 were retrospectively reviewed. Each patient underwent detailed enquiry with regard to the disease history. Ophthalmologic and orthoptic examinations were carried out before the operation, including best corrected visual acuity, cycloplegic refraction, motility evaluation, anterior segment assessment, and fundus examination. The exodeviations were measured by the alternate prisms cover test at both distance (6 m) and near (33 cm) with fixation on accommodative targets. An amount of 7～10 mm unilateral lateral rectus recession was performed according to the quantity of distance deviation. All surgeries were performed by the same surgeon. The Worth 4 Dot test was employed both at distance (2m) and near (33 cm) fixation to assess central and peripheral fusion, respectively. The Titmus stereo test was used to assess stereoacuity. A successful alignment was defined as-8-0 PD in primary gaze while viewing distant and near targets with a minimum of 6 months follow-up. Incomitance was defined as a change of more than 10 PD from primary to lateral gaze.RESULTS:The successful rate in alignment at postoperative day 1-3 and final follow-up periods was 81.2% and 62.3%, and the undercorrection rate were 11.6% and 36.2%, and the overcorrection rate were 7.2% and 1.5%, respectively. There were no relation between the success at final follow-up and age at surgery and initial refractive error (P> 0.05). However, there was a significant relationship between the success at final follow-up and initial deviation (P=0.006, r=-0.328). The number of normal central fusion, peripheral fusion and stereoacuity at the final examination increased statistically compared with that of pre-operation (x2= 21.9,14.0,15.0, P=0.00). There are 6 patients had ocular incomitance at postoperative day 1-3, accounting for 13% of the total number. None of the patients had clinically significant lateral incomitance at final follow-up.CONCLUSIONS:(1) Sixty-nine children with intermittent exotropia (15-35 PD) who underwent unilateral lateral rectus recession acquired a successful rate of 81.2% and 62.3% at postoperative day 1-3 and final follow-up, respectively. (2) The central fusion, peripheral fusion and stereoacuity of children with intermittent exotropia were improved significantly compared with that of pre-operation. (3) None of the patients had clinically significant lateral incomitance at final follow-up. Unilateral lateral rectus recession is a safe and effective treatment for intermittent exotropia in children with exodeviation measuring 15 to 35 PD.