Role of Oxygen in the Genesis of Retrolental Fibroplasia

IN view of the present controversy centring in the role of oxygen in the aetiology of retrolental fibroplasia, we have thought it essential to investigate the influence of varying concentrations of oxygen upon the immature retina. Since it is now well established that the earliest stages of this disease are angioblastic in nature and present as an overgrowth of the developing retinal vessels, it was necessary to select a laboratory animal in which the anatomy and embryology of the retinal vessels were comparable with those in man. In the cat, embryo vascular budding commences at the disc between the 35th and 45th day of intra-uterine life, but the vessels do not reach the retinal periphery until about 3 weeks after birth, whereas, in man, the retinal vasculature is complete at birth. The degree of retinal vascularization in the full-term kitten at birth and in the ensuing 3 weeks is therefore comparable in extent to that in the premature baby. Since, with minor variations, the retinal vascular development is in all other respects very similar to that in man, the kitten appeared to be ideal for our purpose. Our experiments have, therefore, been designed to investigate the immediate and remote effects of high, moderate, and low concentrations of oxygen upon the process of retinal vascularization during the first 3 weeks of the kitten's life. Not all of these experiments have been completed and several others are now in progress, but the findings so far obtained appear to be sufficiently striking and significant to warrant a preliminary communication. Full experimental details and a discussion of the results will be given in a subsequent paper; this report will be confined to a description of the effect of high concentrations of oxygen upon growing retinal vessels, and the subsequent developments which follow the transfer of the animal to ordinary atmospheric conditions.