The Effect of Tetracaine Eyedrop versus Placebo on Oculocardiac Reflex in Strabismus Surgery

Strabismus surgery is accompanied with manipulation of intraocular structures that may lead to oculocardiac reflex (OCR). Due to possible perilous effects of oculocardiac reflex, this study aimed to assess the effects of tetracaine eyedrop as a local nerve impulse cutter on oculocardiac reflex in strabismus surgery.
This clinical-trial study included 70 patients undergone strabismus surgery. They were randomly divided in two groups of placebo (artificial tear) and tetracaine. Immediately after anesthesia and prior to any surgical procedure, three drops of each solution were dropped in four direction of patient's eye. For all patients, heart rate (HR), systolic blood pressure (SBP),diastiloc blood pressure (DBP), mean arterial pressure (MAP), and pulse rate (RR) were assessed in various times. Incidence (20% decrease in heart rate) and severity (mild, moderate, and severe) of oculocardiac reflex in muscle release and cutting, required time for oculocardiac reflex recovery, and atropine dose were compared.
Findings: Incidence of oculocardiac reflex was not different in two groups in release phase (8 and 11 in tetracaine and placebo groups, respectively; P = 0.42); but it was significantly more in cutting phase (2 and 9 in tetracaine and placebo groups, respectively; P = 0.02). Oculocardiac reflex severity was not different in release phase between the two groups (mild: 5, moderate: 2, and severe: 1 in tetracaine, and mild: 8, moderate: 0, and severe: 3 in placebo group; P = 0.44), but was more in placebo group (mild: 1, moderate: 1, and severe: 0 in tetracaine, and mild: 1, moderate: 8, and severe: 0 in placebo group; P = 0.02). Duration of oculocardiac reflex recovery (P = 0.74) and used atropine dose (P = 0.92) were not different between the two groups.
Using local tetracaine eyedrop could merely decrease incidence and severity of oculocardiac reflex in cutting phase of strabismus surgery. For definitive comments, further studies are recommended.