Abstract
Purpose:
To compare changes in horizontal deviation after isolated inferior oblique muscle weakening surgery including myectomy , graded recession, and anterior transposition.
Methods:
We reviewed charts of patients who underwent isolated inferior oblique weakening surgery including myectomy, graded recession, and anterior transposition between January 2005 to September 2012. Horizontal deviation was measured pre-operatively and post-operative measurement closest to the 3 month visit using prism alternate cover testing. We compared absolute changes in horizontal deviation separately in up, down, left, and right gazes using Mann-Whitney U test.
Results:
Of 31 patients identified, 14 underwent unilateral myectomy (IOM), 12 patients underwent unilateral anterior transposition (AT), and 2 underwent bilateral IOM and 3 underwent bilateral AT. Diagnoses included in the study include congenital and acquired superior oblique palsy and primary inferior oblique overaction. In primary position, the mean horizontal shift in unilateral and bilateral IOM was 3 (SD=2.26 ) and 4 prism diopters (PD), respectively. The mean horizontal shift in unilateral AT and bilateral AT was 3 (SD=2.50) and 6 PD, respectively. The mean difference between the unilateral IOM and AT were not statistically significant, however the sample size was small. Most change in horizontal shift was observed in upgaze, where IOM resulted in mean 3 PD and 8 PD shift with unilateral and bilateral surgery. With AT, mean change were 1 and 18 PD for unilateral and bilateral surgery. This large shift seen with bilateral AT is observed in children with primary inferior oblique overaction with poor sensory fusion.
Conclusions:
Unilateral inferior oblique weakening procedures that are commonly used do not cause a clinically nor statistically significant change in horizontal deviation. Larger sample size is needed to do a similar study looking at bilateral inferior oblique IOM and AT.
Keywords: 522 eye movements •
725 strabismus: treatment •
722 strabismus