Indocyanine green angiographic and optical coherence tomographic findings support classification of polypoidal choroidal vasculopathy into two types

Abstract

. Purpose: We assessed the characteristic indocyanine green angiographic (ICGA) and spectral domain optical coherence tomographic (SD‐OCT) findings of two types of polypoidal choroidal vasculopathy (PCV), distinguishable by different filling patterns on ICGA. Methods: Thirty‐one eyes with PCV were classified into types 1 and 2 based on ICGA findings of either the presence or absence of both a feeder and a draining vessel. Characteristic ICGA findings were evaluated for each type of PCV. Spectral domain optical coherence tomographic images of the 31 eyes were also used to compare the two types of PCV. Results: Both a feeder and a draining vessel were observed in 13 eyes (type 1). Eighteen eyes had neither feeder nor draining vessels (type 2). In PCV type 1, a break in the highly reflective line thought to be Bruch’s membrane was detected, corresponding to the feeder vessel in‐growth site on SD‐OCT. This line was straight. In PCV type 2, the highly reflective line exhibited irregular thickness and had highly reflective substances adhering to its lower portion. It curved downward and became increasingly obscure, ultimately disappearing at a point corresponding to the site at which network vessel filling began. The mean subfoveal choroidal thicknesses in eyes with PCV type 1 and PCV type 2 were 199 ± 65 and 288 ± 98 μm, respectively. Conclusions: Our observations support the existence of two distinct types of PCV. The first type represents choroidal neovascularization, whilst the second type involves choroidal vasculature abnormalities.

Polypoidal Choroidal Vasculopathy: Clinical Features and Genetic Predisposition

“…Recent studies have described the subclassification of PCV regarding the presence or absence of BVN (as feeder vessels for the polyp lesions) found by ICGA [57,58,59]. Thus, PCV with apparent BVN is called ‘type 1 PCV' or ‘polypoidal CNV', whereas the one with no or only faint BVN is called ‘type 2 PCV' or ‘typical PCV' (fig.…”

“…Recent studies demonstrated that these 2 angiographic subtypes of PCV showed differences in their clinical course, genetic susceptibility and response to therapy. Type 1 PCV usually has larger lesion sizes due to the larger and more distinct BVN, smaller polyp size on ICGA, smaller choroidal thickness [57,58,59] and lower response to photodynamic therapy (PDT) as compared to type 2 PCV [60]. …”

“…Because CNV in tAMD is thought to pass through Bruch's membrane and grow under (and often over) the RPE layer, at least 1 broken site of Bruch's membrane should be detected. Using OCT, suspected broken sites of Bruch's membrane are often observed in type 1 PCV at the origin of the BVN [57]. These findings suggest that PCV is a type of CNV.…”

“…However, the ‘double layer sign' found in PCV may not necessarily mean the isolation of the RPE from Bruch's membrane. A recent study reported that the isolation between Bruch's membrane and the inner choroidal surface also exhibits a ‘double layer sign', which means that the BVN of the PCV may remain under Bruch's membrane with polypoidal lesions [57] (fig. 6).…”

Pachychoroid disease of the macula

“…This represents the last, most advanced stage of the spectrum of pachychoroid disease of the macula, which can be displayed with the aid of ICGA (obr. 6C) [20,22]. PCV has a predilection for incidence in people of Asian or African race, but may also affect individuals of the white race.…”