THE VITREOUS PROTEIN-CONCENTRATION IS INCREASED PRIOR TO NEOVASCULARIZATION IN EXPERIMENTAL ROP

Purpose. To test the hypothesis that the vitreous protein content is a ltered prior to the development of neovascularization in an experiment al model of retinopathy of prematurity (ROP). Methods. Newborn rats un derwent either a variable oxygen exposure or room air exposure followi ng birth. On day 13 or 14, two days prior to neovascularization, the s teady state vitreous and plasma total protein levels in room-air contr ols or variable-oxygen-exposed newborn rats were determined; similar m easurements were also made for control adult rats. Results. Then was a significant difference (P < 0.05, 2-tailed t-test) in the vitreous pr otein concentration between the age-matched control and experimental n ewborn rats. The protein level in the ROP rat plasma was not significa ntly (P > 0.05) different from that in the age-matched control animals . The vitreous-to-plasma-protein ratios of both the control and ROP ne wborn animals were significantly greater (P < 0.05) than that in the a dults. Conclusions. The results of this study demonstrate, for the fir st time, increased vitreous protein levels prior to the development of neovascularization in the newborn rat model of ROP. In addition, deve lopmental changes in vitreous protein levels were identified. The role of developmental and pathologic alterations in the blood-ocular barri ers in this study is discussed.