Abstract
Purpose :
Retinopathy of prematurity (ROP) is a serious complication in premature infants. Increasing survival of premature neonates has uncovered long-term disorders. Although the inner retina is immediately impaired in ROP, progressive photoreceptor malfunction is also observed, and appears to result from a sustained involution of the choroid, the exclusive source of O2 and nutrients to the subretinal region. Accordingly, converging evidence has shown choroidal involution in ROP infants using enhanced-depth imaging optical coherent tomography (EDI-OCT), an imaging modality that confers safe, efficient and noninvasive probing of retinal and choroidal morphology.
Though OCT has been broadly used in clinic practice and academic researches to detect retinal pathology, its application in studying choroidopathy remains sparse, partly because of poor image resolution at subretina. In the present study, we used Spectralis EDI-OCT to examine choroidal thickness in rats with oxygen-induced retinopathy, an animal model for human ROP.
Methods :
Oxygen-induced retinopathy (OIR) model of ROP was induced by exposing rat pups for the first 2 weeks of life to cycling O2 levels (between 10% and 50%). From P14 to P30, these animals were subjected to EDI-OCT to measure choroidal thickness and to detect other retinal pathologies associated with OIR. Choroidal thickness and retina structure were also studied using gold standard histology techniques (cryosection followed by staining and confocal microscopy).
Results :
High-quality images of rat retina and choroid were obtained using EDI-OCT. Neuroretinal layers, retinal vasculature, retinal pigment epithelium, choroid and the choroid-sclera boarder are well defined. In addition, measurements of choroidal thickness based on OCT images showed thinner choroid in OIR rats on P14 and P30 (20.4μm and 23.3μm, respectively, compared to 31.8μm and 35.5μm in healthy controls), akin to results obtained from gold standard histology methods.
Conclusions :
Our study demonstrated that high-resolution EDI-OCT is a reliable imaging technique to simultaneously study retinal and choroidal structures of small rodents. To our knowledge, this is the first study to examine choroidopathy in small rodents using EDI-OCT. This technique permits longitudinal studies on live animals, thereby reducing the number of experimental animals required.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.