A Study of Ophthalmotonic Consensual Reaction in Rabbits

ABSTRACT

The purpose of the present study is to find out whether the ophthalmotonic consensual reaction really exists and through what channel the reaction is brought about in rabbits. Twenty-eight pigmented male rabbits were divided into four groups of seven rabbits each, and the intraocular pressure of each eye was measured at designated times in each group with a Mueller electronic tonometer under topical anesthesia (0.5% tetracaine hydrochloride). Retrobulbar anesthesia and compression were performed in each group as follows: Group 1: From 56 minutes to 60 minutes after the experiment had begun, the right eye was compressed for 4 minutes with a 50 gm weight by means of a Baillart ophthalmodynamometer Group 2: About one hour after the experiment had begun, 1.0 cc of 2% procaine hydrochloride was given by retrobulbar injection on the right side. Digital massage after retrobulbar injection was avoided and epinephrine was not employed, because they might influence the intraocular pressure. Group 3: After retrobulbar anesthesia had been performed for the right eye at 40 minutes, this eye was compressed by the above described method from 85 minutes to 90 minutes after the experiment had begun. Group 4: After retrobulbar anesthesia had been performed in the left eye at 40 minutes, the right eye was compressed by the above described method from 86 minutes to 90 minutes after the experiment had begun. The data of each experimental group were analyzed statistically by means of the t-test. Four groups of tonometric studies were done with the following results: 1. After the right eye had been compressed with a 50 gm, weight for 4 minutes, the right intraocular pressure was found to be lowered and then immdiately elevated. The intraocular pressure in the left eye was lowered beginning about 20 minutes after the right eye compression, and this phenomenon may be considered as the ophthalmotonic consensual reaction. 2. After retrobulbar anesthesia with 1.0 cc of 2% procaine hydrochloride had been performed for the right eye, the intraocular pressure was found to be lowered, but that of the left eye showed a slight rise and maintenance of the elevated pressure. 3. When the right eye was compressed after retrobulbar anesthesia had been performed, the grade of rising of the intraocular pressure was lower than when retrobulbar anesthesia had not been performed. The intraocular pressure in the left eye showed no significant change, so it can be postumted that the afferent pathway of the ophthalmotonic consensual reaction was blocked by the retrobulbar anesthesia in the compressed right eye. 4. When the right eye was compressed after retrobulbar anesthesia had been performed previously in the left eye, the change of the intraocular pressure in the right eye showed no difference as when retrobulbar anesthesia had not been performed in the left eye. The intraocular pressure in the left eye showed a similar change as when the right eye had not been compressed, so it can be postulated that the efferent pathway of the ophthalmotonic consensual reaction was blocked by the retrobulbar anesthesia in the non-compressed left eye.