Abstract
Abstract: :
Purpose:Develop a quantitative method for longitudinal assessment of retinal vasculature in living rats with an oxygen–induced retinopathy ("ROP rats") that models human retinopathy of prematurity. Methods:ROP rats were created using the oxygen exposures recommended by Penn. Starting at age 16 days, and then at approximately weekly intervals until adulthood (>60 days), full–field digital images were obtained in lightly anesthetized animals with dilated pupils. For each radial retinal vessel, from disc to far periphery, the ratio of the actual length to the distance between disc and periphery provided a tortuosity index. Thus, a perfectly straight blood vessel has an index of 1.0. The tortuosity index was evaluated as a function of age and group, ROP or control. Results:At age 16 days, the mean tortuosity index in ROP (1.07; SD = 0.012) was significantly higher (t=8.46; df= 14; p<0.01) than in controls (1.03 SD = 0.005). In the ROP rats the index gradually decreased indicating resolving vascular abnormality, as occurs in infants with mild ROP. The index did not vary significantly with age in the control rats. Conclusions:This technique provides a feasible method for quantitative, longitudinal assessment of the retinal vasculature in the rat model of ROP. These vascular parameters can be related to serial measures of retinal function in the same animals.
Keywords: imaging/image analysis: non–clinical • retinal development • retinopathy of prematurity