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KMID : 0376219760130010077
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Chonnam Medical Journal
1976 Volume.13 No. 1 p.77 ~ p.85
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On ocular retractory reflex in the rabbits
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Abstract
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In urethane anesthetized rabbits, an experimental observation was made to explore the physiological significance of the ocular retractory reflex. Ocular responses to noxious stimuli applied on the cornea or eye-lid were observed in the normal as well as in the altered eye position. Responses of the extraocular muscles (oculorotatory and oculoretractory muscles) to mechanical stretch were also examined to compare them to the already known stretch reflex response of the other skeletal muscles, and following results were obtained.
1) Dropping of ice water (1-2°C) on a unilateral cornea always elicited the retraction of the ipsilateral eye-ball; on some occasion, the ocular retraction was demonstrated in the bilateral eyes.
2) In response to the single electric shock applied on the lid skin, a rectus muscle and adjacent retractor muscle slip contracted simultaneously, and this demonstrated that the rectus muscle also participates in the ocular retraction.
3) Outward pulling of the eye-ball to stretch the extraocular muscles did not cause phasic ocular retraction, however, the noxious stimulus (electric shock or pinprick) applied on the lid skin elicited ocular retraction even during the outward pulling of the eye-ball.
4) When the extraocular muscles (oculorotatory and oculoretractory muscles) were stretched stepwise, the muscle tension also increased stepwise. However, the electromyographic record revealed no actual increase in the muscle activity.
5) Vestibular excitation of oculorotatory muscle revealed not only tension increase but also marked increase of muscle activities in the EMG record.
6) When the skeletal muscle (Triceps brachii) was subjected to stretch, abrupt and sharp increase of muscle activity was demonstrable in the EMG record.
These experimental results indicate; that the physiological significance of the ocular. retractory reflex is to protect, the eye-ball against noxious stimuli since the oculoretractory and oculorotatory muscles reveal no reflex increase of muscle activity in response to stretch, oculoretractory reflex may not be endowed with the postural regulatory role of the eye-ball position.
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