Extraocular muscle ductions following nasal transposition of the split lateral rectus muscle

Objective To quantify changes in ductions following nasal transposition of the split lateral rectus muscle (NTSLR) for treating third nerve palsy. Design Retrospective cohort study. Participants A single eye from each patient with third nerve palsy treated with NTSLR with ocular motility measurements. Methods Observation of changes in pre- and postoperative ductions. Outcome measures including patient demographic and surgical factors associated with the ability to adduct beyond the midline after NTSLR were evaluated using multivariable logistic regression. Results A total of 116 patients met the inclusion criteria for this study. The NTSLR significantly decreased abduction (median of 0 limitation [interquartile range (IQR), 0–0] prior to surgery to –4 [IQR, –4 to –3] after NTSLR; p < 0.001), with a corresponding improvement in adduction (median, –5 [IQR, –5 to –4] prior to surgery to –4 [IQR, –4 to –3] after NTSLR; p < 0.001). There was no change in median supraduction or infraduction after NTSLR (p > 0.05). The ability to adduct beyond the midline after NTSLR was demonstrated in 42% of patients. Although not statistically significant, a trend toward a postoperative ability to adduct beyond the midline was seen in patients who had concurrent superior oblique muscle tenotomy (odds ratio [OR] = 5.08; 95% CI, 0.91–40.9) or who were designated with partial rather than complete third nerve palsy (OR = 2.29; 95% CI, 0.82–6.70). Conclusions NTSLR improves the horizontal midline positioning of eyes with third nerve palsy. Most eyes lose the ability to abduct, but some regain a modest ability to adduct while vertical ductions remain unchanged.