Influence of High Atmospheric Pressure on the Rabbit's Eye

Abstract

Influence of high atmospheric pressure on rabbit's eye were investigated with a specially devised pressure box. Rabbit was fixed in a cylindrical metal case in a natural position, put in the pressure box, and the eye was observed through glass windows of the box. (1) The width of pupil dilated under high atmospheric pressure (10-60 pounds) with the course of time but not quite in parallel with the degree of pressure. The dilation was not influenced by extirpation of cervical sympathetic ganglion. Atropinizing of the eye did not result in further dilation of the pupil under high pressure. (2) Threshold of the cervical sympathetic stimulation on pupil dilation rose under high pressure (5-60 pounds) with the course of time, but not quite in parallel with the degree of pressure. (3) The smallest luminosity difference required to produce pupil reaction became greater under high pressure (20-60 pounds) with the course of time under the pressure, but not quite in parallel with the degree of pressure. (4) The eye received structural damages under high pressure (20-60 pounds)-hemorrhage and hyperaemia in ciliary body, in retinal and choroid vessels, vacuoles in lens, in inner and outer nuclear layer and ganglion cell layer of retina, irregularities of inner and outer nuclear layer of retina, and exudation between retina and choroid. These damages were not proportional to the degree of pressure or to length of time during which the animal was kept under the high pressure, but rather depended on the rate of pressure change, the more rapid the pressure change, the more marked the damages.