Differences in the corrective effects of vertical transposition accompanied by recession–resection of the horizontal rectus muscles for complicated vertical deviation

To investigate whether the corrective effect differs between upward and downward transpositions or between exotropia and esotropia in vertical transposition accompanied by horizontal rectus muscle recession–resection.

This prospective study investigated 41 patients with concomitant exotropia or esotropia with small-angle vertical deviation who underwent unilateral vertical transposition accompanied by horizontal rectus muscle recession–resection and were followed up for 1 year postoperatively. We analysed the vertical deviation corrective effect, defined as the corrective amount per displacement distance (°/tendon width [TW]). We compared the corrective effects between upward and downward transpositions and between exotropia and esotropia. Additionally, we investigated the correlation between the corrective effect and the studied parameters.

The 1-year vertical corrective effect was 5.2 ± 4.6° (9.0 ± 8.1 prism dioptres [Δ])/TW. The 1-year vertical corrective effect of upward transposition (7.9 ± 4.0° [13.8 ± 7.0Δ]/TW) was higher than that of the downward transposition (3.9 ± 4.4° [6.8 ± 7.7Δ]/TW, P = 0.009). In contrast, upward and downward transposition did not differ between exotropia and esotropia (P = 0.62). Multivariate analyses revealed that the 1-year vertical corrective effect correlated with the vertical transposition direction (upward or downward) and preoperative vertical deviation but did not correlate with the disease type (exotropia or esotropia). The 1-year motor success (vertical deviation ≤ 5Δ) rate was 89%.

The vertical corrective effect of vertical transposition accompanied by horizontal rectus muscle recession–resection is greater in upward transposition than in downward transposition; however, it does not differ between exotropia and esotropia.