Oculocardiac Reflex During Strabismus Surgery: Experience from a Tertiary Hospital

Purpose: To evaluate the incidence of the oculocardiac reflex (OCR) and its associated risk factors during strabismus surgery at a tertiary referral center.

Methods: Over a 2-year period, all strabismus surgery candidates were enrolled in the study. OCR was defined as heart rate reduction ≥15% after traction on extraocular muscle(s). The rate of OCR was determined and possible associations were explored. Variables included age, gender, type of strabismus, nature of surgery (weakening versus strengthening), specified extraocular muscle, times of surgery, and the sequence of operated muscles (eg, first, second, or third operated muscle). We avoided the use of atropine pre- and postoperatively.

Results: Seventy-six patients with mean age of 15±12 years were enrolled; 51.3% of subjects were male. OCR occurred in 65 out of 76 (85.5%) patients and with 84 out of 173 (48.6%) operated muscles. OCR was more common in subjects less than 20 years of age; however, it showed a decreasing trend afterwards. OCR was more frequent during operation on cyclovertical muscles than horizontal recti (P=0.02). Moreover, during procedures on horizontal rectus muscles, OCR was more common if baseline heart rate was more than 61 (P=0.008). OCR was not correlated with gender, type of strabismus, nature of surgery, times of the surgery, or the sequence of operated extraocular muscles.

Conclusions: The great majority of patients undergoing strabismus surgery, especially younger subjects, those undergoing operation on cyclovertical muscles, and subjects with higher baseline heart rate, experience OCR during strabismus surgery. During surgery on cyclovertical muscles, the amount of pull is usually more due to more difficult exposure.