Experimental study of oculocardiac reflex (OCR) with graded stimuli

The present study was conducted to observe the effect of graded mechanical stimuli on occurrence of oculocardiac reflex (OCR). The experiments were carried out in twenty albino rabbits of either sex weighing between 1-2 kg. Changes in heart rate and/or cardiac rhythm (oculocardiac reflex) were studied by applying traction with progressively increasing weights to medial rectus muscle. Mean threshold value of square wave mechanical stimulus just sufficient to produce oculocardiac reflex was found to be 19 +/- 8.52 g. As the traction weights were progressively increased, more and more decrease in heart rate was observed. It was concluded that once the threshold value of stimulus was reached, the oculocardiac reflex showed a graded response with progressively increasing traction weights.