Purpose: To analyze the causes of undercorrection following superior rectus (SR) and lateral rectus (LR) muscle bellies union surgery for esotropia and hypotropia with high myopia.
Methods: This study investigated 26 eyes in 13 patients diagnosed with esotropia and hypotropia with high myopia at the Kyoto Prefectural University of Medicine Hospital and the Baptist Eye Clinic from January 2011 to December 2014. A surgical procedure involving muscle union of the SR and LR muscles was performed in one eye only for each of the patients. They were divided into the following two groups according to postoperative presence of strabismus: 1) the residual strabismus group (strabismus cases with deviation angle at near greater than 10Δ in 3 to 6 months after surgery) and 2) the postoperative orthophoria group. The angle formed by the centers of the SR, globe, and LR (dislocation angle) measured by magnetic resonance imaging (MRI) before surgery was compared between these two groups.
Results: The mean dislocation angle in the operated eyes before surgery was 147.6±16.5° in the residual strabismus group and 140.2±34.5° in the postoperative orthophoria group, with no significant difference observed. The mean dislocation angle in the nonoperated eyes was 135.7±13.4° in the residual strabismus group and 116.4±14.6° in the postoperative orthophoria group, indicating a significant difference (p=0.03, t-test).
Conclusions: In the residual strabismus group, the dislocation angle of the nonoperative eye was larger than that in the postoperative orthophoria group, and the nonoperative eye tended to be dislocated. Even in cases that only involve unilateral convergent strabismus fixus, both eyes should be operated on if the preoperative MRI dislocation angle in both eyes is greater than 120°.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 122: 379-384, 2018.