Factors associated with atypical postoperative drift following surgery for consecutive exotropia

Abstract

Purpose To evaluate the associations of clinical and surgical factors with atypical postoperative drift following surgery for consecutive exotropia. Methods A total of 66 patients with consecutive exotropia (≥10Δ at distance), after historical surgery for esotropia were retrospectively identified at a tertiary medical center. All patients underwent unilateral lateral rectus recession (on adjustable suture) with medial rectus advancement and/or resection. Immediate postoperative target angle was 4Δ–10Δ of esotropia at distance, anticipating mild postoperative exodrift. Actual postoperative drift was calculated as change in distance deviation from immediately postadjustment to 6 weeks. Typical drift was defined as 0Δ–9Δ of exodrift. Excessive exodrift was defined as ≥10Δ. Esodrift was defined as 1Δ or more. Univariate and multiple logistic regression analyses were performed to evaluate for associations with a wide range of clinical and surgical factors. Results Overall there was a median exodrift (4Δ, quartiles 0Δ–10Δ). Of the 66 patients, 18 (27%) showed excessive exodrift; 15 (23%), esodrift. In multiple logistic analyses, larger preoperative distance exodeviation was associated with excessive exodrift (P = 0.01), and non-normal medial rectus attachment status (abnormal [stretched scar, pseudo-tendon], attached to pulley, or behind pulley) was associated with esodrift (P = 0.02). Conclusions Approximately half of patients show atypical drift following unilateral surgery for consecutive exotropia, with larger preoperative distance exodeviation associated with exodrift and non-normal medial rectus muscle status with esodrift. Knowing these associations may help when counseling patients regarding surgical outcomes.

Strabismus Surgery of Consecutive Exotropia

“…In our patients, the dose-effect relationship at 3 months was 2.70 PD/mm surgery, which is in agreement with the literature [4,9,10,14]. This was also true when grouping in just previously operated muscles and at least one non-operated muscle.…”

“…At the 1-week follow-up, we noticed a slight overcorrection with a mean angle of + 0.76 PD of esotropia, which was lower compared to other studies [5,7,9]. In our patients, we observed a mean exodrift of 8 PD after 3 months, which compares well to the literature where an exodrift of 7.4 to 9 PD has been reported 6 months after surgery [5,8] and may increase further with time [6].…”

“…In this large angle cXT subgroup, 54 % of our patients and 44 % in the cohort of Kasi et al [4] had an outcome within 10 PD. A preoperative angle between − 10 to − 20 PD has been associated with a good outcome in cXT surgery [4,7,9]. This applied to only 24 % of our patients versus 37 % of the cohort reported by Kasi et al In these low angle cXT patients, 100 % of our patients had an outcome within 10 PD versus 88 % in the cohort of Kasi et al…”

“…However, the study populations differ in the angle of exotropia at surgery. This is relevant, as it has been shown that a higher preoperative angle results in a lower success rate at the final follow-up [4,7,9].…”

Surgical management of consecutive exotropia: Long-term outcomes

“…Esotropia is generally preferred in the early postoperative period since there is a risk of exodrift over time. 8,9 On the other hand, there is no consensus on the amount of esotropia to be targeted in the postoperative period. This is why it is important to compare surgical methods especially involving long-term results.…”