Session: Free papers Session IV - Eye muscle surgery

Induced Incomitance Following Primary Single-Muscle Recession versus Recess-resect or Bilateral Recession Procedures for Strabismus

Aleksander STUPNICKI¹, Surinder DOSANJH², Saurabh JAIN^1,2

¹UCL Medical School, London, United Kingdom
²Royal Free London NHS Foundation Trust, London, United Kingdom

Introduction: Single-muscle recessions (SMR) for small-angle strabismus offer advantages including shorter operative time, faster recovery and fewer complications while preserving the antagonist muscle for future surgery. However, the asymmetric nature of the procedure poses a risk of inducing incomitance. This study compares the prevalence of induced incomitance following single-muscle recessions with recess-resect procedures (RR) and bilateral recessions (BLR).

Methods: 52 patients with strabismus underwent either single-muscle recession (n=16), recess-resect (n=18) or bilateral recessions (n=18). The exclusion criteria included previous squint surgery, simultaneous surgery on the oblique muscles and previous muscle transposition. From pre- and post-operative measurements of deviation in 9 positions of gaze, the difference in deviation in lateral gaze and vertical gaze was calculated for horizontal and vertical strabismus respectively. Incomitance was defined as a difference in deviation >5PD.

Results: Surgically-induced incomitance occurred in 1 patient following SMR (12.5%), 1 patient following RR (16.7%) and 2 patients after BR (20%) with a range of 6-10PD. Fisher’s exact test showed no statistically significant difference in induced incomitance between either group (p>0.05). We observed a significant correlation between the occurrence of surgically-induced incomitance and pre-operative mean angle of deviation for all groups combined (p=0.04), and the total amount of incision for SMR and BLR combined (p<0.01).

Conclusions: The risk of induced incomitance following SMR is comparable to RR and BLR, but increases for large-angle strabismus and with larger incisions. Due to numerous advantages, ophthalmologists should continue to consider single-muscle recessions for small-angle strabismus but bear the risk of incomitance when operating on patients with large deviations.