STUDIES ON DEVELOPING RETINAL VESSELS* II. INFLUENCE OF RETINAL DETACHMENT ON OXYGEN VASO-OBLITERATION BY

BY direct observation, it was recently shown that the obliterative action of high concentrations of oxygen on the ingrowing vessels of the kitten retina may be prevented by retinal detachment (Ashton and Cook, 1954). The obliterated vessels re-open as soon as detachment begins, indicating that close apposition between retina and choroid is necessary for the obliterative phenomenon to operate. Since it is known that vaso-obliteration is also dependent upon the concentration of oxygen, it would appear that, once the retina detaches, effective levels of oxygen no longer reach this tissue. The maximum period, however, for which the vessels of the detached retina were observed in hyperoxia was 121 hours, and the question remained whether a longer period of exposure might not be required for oxygen to diffuse across the subretinal space and reach the retina in sufficient concentra-tion. In this paper experiments are reported which show that retinal detachment prevents the vaso-obliterative effect of oxygen even when high concentrations are continuously maintained for 4 days. Survival in air after such detachment and exposure is followed by proliferative changes which are difficult to interpret in view of our findings on the effect of detachment alone (Ashton and Cook, 1955). Experimental Findings Experiment 76.-One mother cat and three kittens (ki, k2, and k3) 4 days old. Plan.-Through a needle withdraw enough vitreous from the right eye of each anaes-thetized kitten to induce retinal detachment. Left eye to remain as control. Then put mother and litter into 70-80 per cent. oxygen for 4 days. Then kill all the kittens to demonstrate