Comparison Study On Unilateral Medial Rectus Recession Versus Bilateral Medial Rectus Recession For Treatment Of Convergence Excess Esotropia In Children

BACKGROUND AND OBJECTIVE:The cilinical feature of convergence-excess esotropia is the near deviation excesses distance deviation by10PD or more with full cycloplegic refraction correction. It is divided into3types according to gradient methods:accommodative refractive esotropia with a high accommodative convergence to accommodation ratio(AC/A), nonaccommodative non-refractive esotropia with a high AC/A ratio, esotropia of nonaccommodative convergence excess. The latter two types are clinically rare. The commonly used treatment option for convergence-excess esotropia is bifocal spectacles. The surgery is needed when there is a manifest esotropia in distance or the near deviation is still great after wearing bifocal spectacles. Strabismus surgery is also the only treatment for esotropia of nonaccommodative convergence-excess type. Benefit from the simple surgical procedures, definite curative effects and fewer complications, bilateral medial rectus recession was considered to be a classic operation method for treatment of convergence-excess esotropia. Recent evidence shows that unilateral medial rectus muscle recession is a safe, effective and predictable treatment for small-to moderate-angle horizontal esodeviations. But this procedure has not been widely accepted nor widely studied. This study was undertaken to compare the surgical outcome of unilateral medial rectus recession and bilateral medial rectus recession in children with convergence excess esotropia.METHODS:Retrospective consecutive interventional case series. Sixty-six children with convergence excess esotropia who met the inclusion criteria and underwent unilateral medial rectus recession (29cases) and bilateral medial rectus recession (37cases) were enrolled in this study from July2009to March2013in the Eye Center of Shandong Provincial Hospital affiliated to Shandong University. The target angle for surgery was decided according to the near deviation with full cycloplegic refraction correction. A successful alignment was defined as0-+9PD in primary gaze determined with the alternate prism and cover test while viewing distant and near accommodative targets. A Chi-square test was applied to compare the success rates, undercorrection rates and overcorrection rates between the two groups with different procedures. Paired T test was used to compare the near-distance disparity (N-D) before and after surgery in each group. Independent T test was used to compare the near deviations, distance deviations and N-D at the final postoperative follw-up examination between the two groups and to compare the changes of N-D before and after surgery between the two groups.RESULTS:There was no significant difference in success rates, undercorrection rates and overcorrection rates (P>0.05) and no significant difference in near deviations(P=0.253) and distance deviations(P=0.140) between the two groups, with a mean follow-up period of (11.62±8.21) months. The N-D in patients with unilateral medial rectus recession before and after surgery were15.21±4.29PD and3.93±5.61PD, respectively, and the difference was significant(P=0.000). The N-D in patients with bilateral medial rectus recession before and after surgery were15.37±4.69PD and3.84±4.77PD, respectively, and the difference was significant(P=0.000). There was no significant difference in N-D between the two groups at final follow-up(P=0.322). The changes in N-D before and after surgery were11.28±7.00PD in patients with unilateral medial rectus recession and11.54±5.82PD in patients with bilateral medial rectus recession. There was no significant difference in changes of N-D between the two groups(P=0.249).44cases regained ocular alignment, among whom30cases can cooperate for the Worth4-dots and stereo test.22cases obtained peripheral fusion and4cases with central fusion.16cases obtained gross stereopsis of different levels (3000arcs to400arcs).4cases obtained normal stereopsis (40arcs).CONCLUSION: Based on the near esodeviation with full cycloplegic refraction correction, graded unilateral medial rectus recession for small-to moderate-angle convergence excess esotropia was as effective as graded bilateral medial rectus recession for moderate-to large-angle convergence excess esotropia in children. Both of the procedures can reduce the N-D effectively.