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Experimental study of oculocardiac reflex (OCR) with graded stimuli
Indu Khurana1, Rajeev Sharma, A K Khurana
1Department of Physiology, Postgraduate Institute of Medical Sciences, Rohtak 124 001.
Indian Journal of Physiology and Pharmacology
|October 21, 2006
Summary
Mechanical eye pressure triggers the oculocardiac reflex (OCR) in rabbits. Increasing traction on eye muscles causes a dose-dependent decrease in heart rate once a specific threshold is met.
Area of Science:
- Ophthalmology
- Physiology
- Cardiology
Background:
- The oculocardiac reflex (OCR) is a physiological response involving a decrease in heart rate due to stimulation of the trigeminal nerve, often elicited by pressure on the eyeball or traction on eye muscles.
- Understanding the quantitative relationship between mechanical stimuli and OCR is crucial for surgical procedures and clinical assessments.
Purpose of the Study:
- To investigate the effect of graded mechanical stimuli on the occurrence and intensity of the oculocardiac reflex (OCR).
- To determine the threshold mechanical stimulus required to elicit OCR and observe its response to increasing traction force.
Main Methods:
- Experiments were conducted on twenty albino rabbits (1-2 kg).
- Progressively increasing weights were applied to the medial rectus muscle to induce traction.
- Changes in heart rate and cardiac rhythm were monitored to assess the oculocardiac reflex.
Main Results:
- The mean threshold value for mechanical square wave stimulus sufficient to produce OCR was found to be 19 +/- 8.52 g.
- A progressive increase in traction weight led to a corresponding decrease in heart rate.
- The oculocardiac reflex demonstrated a graded response to increasing mechanical stimuli beyond the threshold.
Conclusions:
- The oculocardiac reflex exhibits a graded response to mechanical traction applied to the medial rectus muscle in rabbits.
- A specific threshold of mechanical stimulus is required to initiate the oculocardiac reflex, with response intensity correlating to stimulus magnitude.
