First Author: C.Chung HONG KONG
Co Author(s): H. Tang S. Li K. Li
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1. To compare the imaging of retinal vein occlusion (RVO) with optical coherence tomography angiography (OCT-A) and fluorescein angiography (FA) 2. To evaluate the role of the two imaging modalities in clinical management
The study was conducted by the Kowloon East Cluster Ophthalmic Service (United Christian Hospital and Tseung Kwan O Hospital). It was approved by the Research Ethics Committee of the Hospital Authority (Ref: KC/KE-16-0229/ER-1) and compliant to the Declaration of Helsinki.
This is a consecutive case series of all patients with RVO from 1st June 2015 - 31th August 2015. Fluorescein angiography (FA) was performed with the Heidelberg Retinal Angiography and optical coherence tomography System (Spectralis®, HRA-OCT; Heidelberg Engineering, Germany). Optical coherence tomography angiography (OCT-A) was performed with the AngioVue software on the RTVue XR Avanti Spectral Domain OCT (Optovue Inc., Fremont, CA) using the 3 x 3 mm scanning protocols. All ophthalmic imaging was performed by a single ophthalmic photographer. The patient identity of the FA and OCT-A reports was independently coded. An experienced retinal specialist blinded from patient identity assessed the imaging reports according to the presence or absence of the following parameters: 1. Enlargement of foveal avascular zone (FAZ) 2. Capillary non-perfusion 3. Microaneurysm 4. Venous congestion 5. Vascular tortuosity The agreement between FA and OCT-A was assessed with Cohen’s kappa coefficient on SPSS 20.0 for windows. A significant level of p < 0.05 was taken.
In the study period, twelve RVO patients were evaluated with both OCT-A and FA. Between FA and OCT-A, good agreement was found for microaneurysms (100%, Kappa’s coefficient 1, p = 0.001) and venous congestion (83.33%, Kappa’s coefficient 0.571, p = 0.028). For the parameters of FAZ enlargement, venous congestion and tortuosity, poor agreement was found between FA and OCT-A (p > 0.05). OCT-A revealed much more capillary non-perfusion (91.67%, 11/12 cases) than FA (58.33%, 7/12 cases). OCT-A also revealed more FAZ enlargement (75.00%, 9/12 cases) than FA (33.33%, 4/12 cases). On FA, vascular leakage was shown in 83.33% (10/12 cases).
For RVO, OCT-A is able to reveal more FAZ enlargement and capillary non-perfusion. Inherent to the principle of imaging, vascular leakage is only shown on FA. While the retinal perfusion status and the need for pan-retinal photocoagulation (PRP) is better assessed on OCT-A, vascular leakage from neovascularization as shown on FA is useful for the assessment of treatment response. Albeit having good agreement between FA and OCT-A, the parameters of microaneurysms and venous congestion are less useful for prognostic purpose and guidance of management. OCT-A and FA are complementary tools in the evaluation of retinal perfusion in RVO. The need for PRP is better assessed on OCT-A, while FA has its value in assessing treatment response.