Multimodal Imaging in Pachychoroid Neovasculopathy: A Case Report

Pachychoroid spectrum diseases were first recognized in 2013 when Warrow et al.¹ described pachychoroid pigment epitheliopathy. The pachychoroid spectrum includes 4 disease groups: pachychoroid pigment epitheliopathy, central serous chorioretinopathy, pachychoroid neovasculopathy (PNV), and polypoidal choroidal vasculopathy. Pachychoroid spectrum diseases are characterized by increased choroidal thickness, dilation of the outer choroidal veins (pachy-veins), and thinning of Sattler’s and choriocapillaris layers.²

Multimodal imaging methods are used to understand the disease pathophysiology and in diagnosis. Indocyanine green angiography (ICGA) is shown to be superior to fundus fluorescein angiography (FFA) for detailed imaging of choroid neovascularization (CNV) and diagnosis of choroidal polyps. Thanks to its longer wavelength, ICGA enables better visualization of lesions underlying the retinal pigment epithelium (RPE), even in the presence of blood, exudate, and pigment epithelium detachment (PED).^3,4 Advances in the field of optical coherence tomography (OCT) have also enabled imaging of choroidal structures in addition to the retina.^5,6 OCT angiography (OCT-A), a relatively new technology, provides structural information about the retinal and choroidal vessels without the need for contrast material injection.⁷

In this case report, we analyze the findings obtained with various imaging modalities from a patient with PNV who presented with a 2-month history of blurred vision.

PNV was first described by Pang and Freund⁸ in 2015. The disease may consist of type 1 CNV that develops secondary to central serous chorioretinopathy or pachychoroid pigment epitheliopathy. PNV should be suspected in cases of thickened choroid with type 1 CNV without characteristic findings of age-related macular degeneration (AMD) such as drusen or hemorrhages. It is characterized by the presence of shallow, irregular PED.

In a study by Miyake et al.⁹ including 200 patients diagnosed with PNV and AMD, 19.5% of the cases were diagnosed with PNV. Subfoveal choroid thickness was found to be greater in patients with PNV than in those with AMD. They reported that genetic mutations were detected less frequently in patients with PNV. In addition, PNV was observed in younger patients compared to AMD.¹⁰

The etiopathogenesis of pachychoroid spectrum diseases involves microtrauma to the Bruch’s membrane from the enlarged pachy-veins in the Haller’s layer. This causes choriocapillaris loss and RPE changes. Neovasculopathy develops as a result of extension of neovascularization beneath the RPE.¹

FFA and ICGA are used in the diagnosis of CNV and are known to cause nausea and anaphylaxis in rare cases.¹¹ OCT-A enables image acquisition by serial OCT scanning and is a reliable method that allows imaging of retinal and choroidal vasculature without needing any dye injection.⁷ The tangled vascular network under the shallow irregular PED can be imaged with OCT-A. In a study including 16 patients (22 eyes) with shallow irregular PED, CNV was detected in 95% of the patients with OCT-A. Compared to other angiography techniques, OCT-A is shown to be more successful in demonstrating type 1 CNV.¹²

Similarly, in the present case we observed shallow PED, subretinal fluid, thickened choroid, and pachy-veins on spectral domain OCT and appearance consistent with type 1 CNV in FFA and ICGA. OCTA showed a CNV network in the areas corresponding to the type 1 CNV observed on ICGA. In a case series by Azar et al.¹³ including 5 PNV patients, the presence of neovascularization could not be fully identified with FFA and ICGA in 2 patients, whereas the presence of tangled filamentous vascular network was detected in all of the patients with OCT-A. Therefore, these findings indicate that OCT-A can detect CNV before FFA and ICGA in pachychoroid spectrum diseases.

In conclusion, as we have also observed in our case, non-invasive OCT-A imaging generally supports fundus angiography images with regard to the diagnosis of type 1 CNV in PNV. OCT-A should be used in combination with other methods for the detection of vascularization in AMD presenting with shallow PED and in pachychoroid spectrum diseases.