Chronic Sixth Nerve Palsy Surgical Alternative Improves Esotropia Treatment

Vertical rectus belly transposition paired with ipsilateral medial rectus recession shows benefits in correcting esotropia that a superior rectus transposition approach does not.

Modified vertical rectus belly transposition plus ipsilateral medial rectus recession (mVRBT-MRc) is a superior method of correcting esotropia in patients with chronic sixth nerve palsy compared with augmented superior rectus transposition plus MRc (aSRT-MRc), according to a report published in JAMA Ophthalmology.

Researchers conducted a parallel-design, double-masked, single-center, randomized clinical trial to compare the efficacy of mVRBT-MRc vs aSRT-MRc in patients with chronic sixth nerve palsy.

Between January 15, 2018, and May 24, 2021, eligible patients with unilateral chronic sixth nerve palsy were randomly assigned to receive either mVRBT-MRc or aSRT-MRc. Patients were scheduled for follow-up visits at 1 month and 6 months. The primary outcome was change of horizontal deviation in primary position from baseline to 6 months.

A total of 25 patients (mean age, 45.4±12.6 years; 60% women and 40% men) participated in the study, with 13 assigned to the mVRBT-MRc group and 12 assigned to the aSRT-MRc group. The mean baseline horizontal deviation was 65.7±10.8 prism diopters (Δ) in the mVRBT-MRc group and 60.5±14.1 Δ in the aSRT-MRc group. Most demographic and clinical characteristics were well balanced among the groups. 

Based on these results, mVRBT-MRc may be a promising 1-step procedure for chronic sixth nerve palsy, preferably for those with a large esotropia of more than 60Δ, if these results are confirmed in larger, diverse cohorts with longer follow-up.

At 6 months, the horizontal deviation change from baseline was greater in the mVRBT-MRc group compared with the aSRT-MRc group (66.3 vs 51.5 Δ; adjusted group difference, 10.9 Δ; 95% confidence interval [CI], 5.3-16.6 Δ; P =.001). The researchers reported that 4-times as many patients in the mVRBT-MRc group achieved greater than 60 Δ correction than in the aSRT-MRc group. 

The team observed no significant differences between the mVRBT-MRc group and aSRT-MRc group for improvement of abduction limitation (difference, -0.2; 95% CI, -0.8 to 0.5; P=.64) and a higher proportion of undercorrection in the aSRT-MRc group compared with the mVRBT-MRc group (difference, 45%; 95% CI, 16%-75%; P =.01). They saw no significant differences for other suboptimal outcomes between the groups.

“Based on these results, mVRBT-MRc may be a promising 1-step procedure for chronic sixth nerve palsy, preferably for those with a large esotropia of more than 60Δ, if these results are confirmed in larger, diverse cohorts with longer follow-up,” the researchers explain.

Limitations of the study included the small sample size comprised of all Chinese patients, more patients with a preoperative esotropia ranging from 71 Δ to 85 Δ in the mVRBT-MRc group than the aSRT-MRc group (38% vs 17%), a relatively short follow-up period, inability to evaluate objective torsion in all patients due to severe abduction limitation, and the subjective nature of participants’ abducting effort and the examiners’ judgment.

References:

Yao J, Jiang C, Wang X, et al. Effect of modified vertical rectus belly transposition vs augmented superior rectus transposition plus medial rectus recession for chronic sixth nerve palsy: a randomized clinical trial. JAMA Ophthalmol. Published online August 4, 2022. doi:10.1001/jamaophthalmol.2022.2856