Prevention of oculocardiac reflex (O.C.R) during extraocular muscle surgery

In the present study the effectiveness of intravenous atropine sulphate which blocks the peripheral muscarinic receptors at the heart and retrobulbar xylocaine hydrochloride which blocks the conduction at ciliary ganglion on the afferent limb of OCR was studied during strabismus surgery. The study was conducted on fifty three patients of either sex having squint of more than ten years duration. The patients were randomly allocated into four groups. No preanaesthetic medication with atropine or retrobulbar block with xylocaine was given in control group of patients. In the second group, only preanaesthetic medication with atropine was given; while in the third group only retrobulbar injection of xylocaine was given five minutes before operation. In the last group both atropine as preanaesthetic medication and xylocaine as retrobulbar block were given. The electrocardiographic recordings were taken before and throughout the operative procedure. It was interesting to note that in the group where atropine and xylocaine were used none of the patients exhibited activation of OCR. Results have been discussed.