The Effect of Ocular Hypertension Caused by Red Cells on the Rate of Formation of Aqueous Humor

¹ Department of Experimental Ophthalmology, the Wallenberg Laboratory, Institute of Pharmacology, University of Uppsala Uppsala, Sweden

Red cells were added to the anterior chamber fluid in one eye in 10 vervet and 10 cynomolgus monkeys. ¹³¹I-labeled albumin was used to measure the rate of outflow of anterior chamber fluid in one eye and ¹²⁵I-albumin in the other. In the eyes with red cells the intraocular pressure was about 9 mm. Hg higher than in the controls. The rate of outflow of anterior chamber fluid in the red cell eye minus that in the control eye was divided by the difference in intraocular pressure. The ratio, representing the reduction in rate of outflow per millimeter of Hg pressure difference, was about the same in the two species, and the over-all average value for the suppressibility of the rate of aqueous humor formation was 0.060 ± 0.013 µl per minute per millimeter Hg. In 10 eyes receiving red cells but with the intraocular pressure adjusted to the same level as in the control eyes by means of a reservoir, the rate of aqueous humor formation toas 1.33 ± 0.0S µl per minute. In the control eyes it was 1.20 ± 0.07 µl per minute. The difference, 0.13 ± 0.05 µl per minute, was probably significant, P<0.05. If an alloioance is made for the somewhat doubtful tendency of the red cells per se to enhance the rate of formation of aqueous humor, in the pressure region investigated, the average suppressibility of the rate of aqueous humor formation becomes 0.07 µl per minute per millimeter Hg. The results indicate that there are large variations in the suppressibility of the rate of aqueous humor formation from one animal to another and that it may vary also in the individual eye.