ABSTRACT
BACKGROUND AND PURPOSE: A-pattern esotropias without superior oblique muscle overaction form a small but distinct group among A and V pattern anisotropias. The purpose of this study was to determine the results of ungraded 5 mm bilateral medial rectus muscle transpositions as a treatment of A anisotropia in esotropic patients, and to study these results with relation to the magnitude of preoperative A anisotropia and to the magnitude of preoperative esotropia in primary position. METHODS: Patient data on all 37 esotropic patients who had 5 mm elevation of the medial rectus muscle insertion for correction of A anisotropia at our institution during the previous 25 years were studied. We considered the surgical result to be "satisfactory" when a total correction, and A pattern less than 10 Prism Diopters (PD) or a V pattern less than 15 PD were obtained. The patients were divided into different groups, according to the magnitude of the preoperative A pattern and according to the magnitude of the preoperative esotropia in primary position. For statistical analysis, the Chi Square and the Fisher Tests were employed. RESULTS: "Satisfactory" results were found in 70.3% of the cases. The mean correction of A anisotropia was 11.4 PD (76.1%), which corresponded to 2.3 PD per millimeter of transposition. "Unsatisfactory" results were more prevalent in patients with esotropia in primary position larger than 40 PD (p=0.0418). CONCLUSIONS: A five millimeter vertical transposition (elevation) of both medial rectus muscles is an effective treatment for correction of A anisotropia in most esotropic patients, but is associated with unsatisfactory results when the preoperative esotropia in primary position is larger than 40 PD.
