Changes in Lateral Comitance After Asymmetric Horizontal Strabismus Surgery

Abstract

IMPORTANCE Asymmetric horizontal strabismus surgery is often performed to correct primary gaze alignment without considering the symptoms that may result from misalignment in the patient's side gaze. Surgical choices influence alignment in side gaze and may contribute to functional and social deficits. OBJECTIVE To identify the surgical procedures associated with changes of alignment in side gaze to help inform surgical planning for patients with horizontal strabismus. DESIGN, SETTING, AND PARTICIPANTS The medical records of 1081 horizontal strabismus surgical procedures that were performed at Boston Children's Hospital during a 2-year period were retrospectively reviewed. Only records with strabismus measurements recorded in the right and left gaze before and after surgery were included. Data analysis was conducted from September 1, 2012, through June 7, 2015. MAIN OUTCOMES AND MEASURES Change in comitance (CIC), determined by measuring the horizontal comitance (the difference between right-and left-gaze strabismus measurements) before and after surgery. RESULTS The review identified 569 patients who met the inclusion criteria. Of the 491 patients with comitant preoperative alignment, 59 developed postoperative incomitance, of whom 53 (89.9%) had asymmetric surgery. Of the 78 patients with incomitant preoperative alignment, 36 patients' (46.2%) deviation had improved to comitance after surgery; 32 (88.9%) of these patients had asymmetric surgery. Asymmetric 2-muscle surgery had a median CIC of 4.0 while symmetric 2-muscle surgery had a median CIC of 1.5 (difference in CIC, 2.5; 95% CI, 2.0-3.0; P < .001). A CIC of 25 prism diopters or more was observed in 6 patients who underwent asymmetric surgery (0 with symmetric surgery). New postoperative incomitance was symptomatic in at least 17 patients (28.8%). CONCLUSIONS AND RELEVANCE Asymmetric strabismus surgery can treat incomitant deviations, but it can also create symptomatic incomitant deviations in patients who were previously comitant. Surgical planning should include consideration of the potential for CIC, including the potential for unsatisfactory appearance in side gaze. Patients with binocular vision will be sensitive to diplopia in any gaze direction; in such cases, the consequences of asymmetric surgery should be considered with particular care.

Incomitance and Eye Dominance in Intermittent Exotropia

“…Lateral incomitance can be large enough to influence surgical planning. 41 , 43 In a recent study, 63/155 patients (41%) undergoing surgery for intermittent exotropia had lateral incomitance of >5 prism-diopters. 44 For patients with sizeable incomitance in primary gaze, such as those identified in our study, one might consider performing slightly asymmetrical surgery to obtain optimal results.…”

Surgical management of intermittent exotropia: do we have an answer for all?

“…In a study by Graeber et al , 90% of patients having postoperative lateral incomitance had undergone asymmetrical surgery 32. While another study in children undergoing asymmetrical surgery, reported that 30% of cases with postoperative induced incomitance, had diplopia in side gazes, while 30% had concerns regarding their cosmetic appearance in side gazes even after 6 months 32 35. On the contrary, unilateral surgery reduced the preoperative lateral incomitance in half of the cases 32.…”

“…While another study in children undergoing asymmetrical surgery, reported that 30% of cases with postoperative induced incomitance, had diplopia in side gazes, while 30% had concerns regarding their cosmetic appearance in side gazes even after 6 months 32 35. On the contrary, unilateral surgery reduced the preoperative lateral incomitance in half of the cases 32. However, the evidence to show that unilateral surgery can induce lateral incomitance is scarce with only a couple of studies reporting the phenomenon, and more evidence is needed.…”

“…Unilateral R&R is an asymmetrical procedure and there is a possibility of inducing lateral incomitance which is 10 times more compared with the symmetrical surgery in preoperative comitant strabismus 32–35. In a study by Graeber et al , 90% of patients having postoperative lateral incomitance had undergone asymmetrical surgery 32.…”

“…Unilateral R&R is an asymmetrical procedure and there is a possibility of inducing lateral incomitance which is 10 times more compared with the symmetrical surgery in preoperative comitant strabismus 32–35. In a study by Graeber et al , 90% of patients having postoperative lateral incomitance had undergone asymmetrical surgery 32. While another study in children undergoing asymmetrical surgery, reported that 30% of cases with postoperative induced incomitance, had diplopia in side gazes, while 30% had concerns regarding their cosmetic appearance in side gazes even after 6 months 32 35.…”