High Resolution Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Visualization of Choroidal Vascular Occlusion

Van Phuc Nguyen,Wei Zhang,Jessica Henry,Yanxiu Li,Xueding Wang,Yannis M Paulus

doi:10.3390/ijms21186508

Abstract

Photoacoustic microscopy is a novel, non-ionizing, non-invasive imaging technology that evaluates tissue absorption of short-pulsed light through the sound waves emitted by the tissue and has numerous biomedical applications. In this study, a custom-built multimodal imaging system, including photoacoustic microscopy (PAM) and optical coherence tomography (OCT), has been developed to evaluate choroidal vascular occlusion (CVO). CVO was performed on three living rabbits using laser photocoagulation. Longitudinal imaging of CVO was obtained using multiple imaging tools such as color fundus photography, fluorescein angiography, indocyanine green angiography (ICGA), OCT, and PAM. PAM images were acquired at different wavelengths, ranging from 532 to 700 nm. The results demonstrate that the CVO was clearly observed on PAM in both two dimensions (2D) and 3D with high resolution longitudinally over 28 days. In addition, the location and margin of the CVO were distinguished from the surrounding choroidal vasculature after the injection of ICG contrast agent. PAM imaging was achieved using a laser energy of approximately 80 nJ, which is about half of the American National Standards Institute safety limit. The proposed imaging technique may provide a potential tool for the evaluation of different chorioretinal vascular disease pathogeneses and other biological studies.

Highlights

Choroidal vascular occlusion (CVO), or choroidal ischemia, is disruption of the blood flow to the choroid of the eye that can cause irreversible, severe vision loss [1,2,3]
The choroidal vascular occlusion (CVO) model was monitored with color fundus photography, fluorescein angiography (FA), indocyanine green angiography (ICGA), photoacoustic microscopy (PAM), and Optical coherence tomography (OCT) imaging longitudinally over a period of 28 days
There was no evidence of blood perfusion or reperfusion at the location of laser injury post CVO up to 28 days, indicating that choroidal vessels were disrupted in this region for at least 28 days

Summary

Introduction

Choroidal vascular occlusion (CVO), or choroidal ischemia, is disruption of the blood flow to the choroid of the eye that can cause irreversible, severe vision loss [1,2,3]. CVO can be diagnosed by indocyanine green angiography (ICGA) and fluorescein angiography (FA) [4]. The absence of fluorescent dye in the choroidal vasculature or choriocapillaris is evidence of occlusion. FA and ICGA are invasive procedures requiring the use of exogenous contrast agents. Fluorescent dyes are approved by the US Food and Drug Administration (FDA), the dye may cause side-effects such as nausea or vomiting in 5–16% of patients and can cause severe allergic reactions including anaphylaxis and death [5,6,7,8]

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Conclusion