In Vivo Evaluation of Laser-Induced Choroidal Neovascularization Using Spectral-Domain Optical Coherence Tomography

Abstract

To describe the in vivo evolution of laser-induced choroidal neovascularization (CNV) in mice using spectral domain optical coherence tomography (SD-OCT). Laser photocoagulation was applied to the mouse fundus using a 532-nm diode laser (100, 150, and 200 mW; 100-μm diameter, 0.1-second duration). SD-OCT examination was performed immediately after laser application and at days 3, 5, 7, 14, 21, and 28 after laser. Fluorescein angiography (FA) was performed at day 5, 7, 14, and 28. Acquired SD-OCT images were analyzed to describe morphologic features, measure CNV size and retinal thickness, and assess the frequency of lesions resulting in fluid accumulation. Finally, SD-OCT images were compared to fluorescein angiograms and histologic sections with immunostaining at similar time points. SD-OCT allowed visualization of the initial laser damage and the subsequent stages of the injury response. CNV formation reached its maximum size at day 5. By day 7, significant size reduction was observed (P < 0.001), continuing through days 14 and 28. Exudation signs, such as fluid accumulation and increase in retinal thickness, followed the same time course, with a peak at day 5 and a decrease by day 7. Delivery of higher laser energy levels to the RPE/choroid complex resulted in a significant percentage of lesions demonstrating excessive chorioretinal damage without CNV formation. SD-OCT is a fast and reliable tool for the in vivo evaluation of laser-induced CNV, allowing quantification of lesion size and exudation parameters. Moreover, it provides morphologic information that correlates with histologic findings.