Optical coherence tomography angiography (OCT-A) in an animal model for laser-induced choroidal neovascularization

Abstract

Purpose : Optical coherence tomography angiography (OCT-A) is a new diagnostic imaging modality for noninvasive three-dimensional visualization of retinal and choroidal vascular structures without fluorescent dye injection. We compared OCT-A with conventional fluorescein angiography in an animal model of laser-induced choroidal neovascularization (CNV).

Methods : Dark Agouti rats underwent argon laser photocoagulation to induce CNV. In-vivo imaging using combined confocal scanner laser ophthalmoscopy (cSLO) and OCT-A imaging (Heidelberg Spectralis, Heidelberg Engineering, Germany) was performed before and directly after laser treatment as well as at day 3, 7, 14 and 21. OCT-A en-face images were compared to cSLO images obtained by conventional fluorescein angiography (FA). Post-mortem analysis included immunohistochemistry of retinal and choroidal blood vessels.

Results : High-resolution non-invasive imaging of normal superficial, intermediate and deep retinal plexus as well as choroidal blood vessels in rats by OCT-A was possible. Within laser lesions, signs of CNV formation occurred at day 7 with progression in size and number of small vessels until day 21. Development of CNV was associated with localized dye leakage on FA. Compared with OCT-A, invasive FA imaging did not allow for a detailed visualization of the formation of new small vessels within laser lesions.

Conclusions : This study demonstrates that in vivo OCT-A imaging can be performed in small animals like rats. Detailed and high-contrast images of the retinal and choroidal vascular plexus can be visualized without invasive dye injection. OCT-A imaging may allow for a more precise, spatial analysis of new blood vessel formation in CNV animal models as compared with conventional FA.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.