Objective:To prepare a quantified animal model of retinopathy of prematurity by economic and easy method. Methods:A total of 44 postnatal day 7 wistar rats were randomly assigned into 2 groups according to different oxygen inhalation concentration(n=22).Experimental group was exposed to 75% oxygen for 5 days

and them deprived of oxygen supply suddenly and exposured in air for 5 days.The Control group was exposed to room air in same experiment condition.The retinal vascular development and proliferation were evaluated by stretched preparation (ADPase stained retina)and eyeball cross-section

The expression of vascular endothelial growth factor(VEGF) was detected by immunohisto-chemical stain.Results: The central vessels became tortuous and constricted and the central avascular area increased in high-concentration oxygen environ-ment.But hypoxia environment made great vessels of retina broaden and abnormal curvature become obvious

neova- scularization was seen in the Experimental group.The average numbers of neovascular nuclei which breakthrough limiting membrane of amphiblestrodes in the Experimental group and the Control group were 32.800 0±0.767 8 and 2.750 0±0.716 4 respectively.Stain of VEGF was weaker in the control group than in the treated group.Conclusion:The rat modle of retinopathy of prematurity has powerful repeatability

high constancy and can be used in quantitative study.It is a suitable mode to study the pathogenesis and therapy of retinopathy of prema-turity.