Understanding aneurysmal type 1 neovascularization (polypoidal choroidal vasculopathy): a lesson in the taxonomy of ‘expanded spectra’ – a review

Abstract

The term aneurysmal type 1 neovascularization is derived from terminology, which is established in the literature but has fallen out of use. We believe that aneurysmal type 1 neovascularization accurately describes the lesions which define the entity known as polypoidal choroidal vasculopathy (PCV). Over the last three decades, the clinical spectrum of PCV has expanded to recognize the occurrence of the aneurysmal (polypoidal) lesions in different contexts, resulting in a complex and unwieldy taxonomy based sometimes on circumstantial findings rather than mechanistic considerations. Advances in multimodal imaging provides increasingly convincing evidence that the lesions which define various forms of PCV are indeed vascular and arise from type 1 neovascular networks. The understanding of PCV as type 1 neovascularization with aneurysms renews focus on the question as to why some patients with type 1 neovascularization develop aneurysms while others do not. Conceptual themes and potential for further study are discussed.

Hyperreflective material as a biomarker in neovascular age-related macular degeneration

“…Moreover, the location of HRM, among other imaging features, may help to distinguish the different subtype of CNVs. According to a recent classification CNVs may be classified as type 1 (under the RPE), type 2 (subretinal), type 3 (formerly referred to as retinal angiomatous proliferatiion), and aneurysmal type 1 neovascularization (formerly referred to as polypoidal choroidal vasculopathy) [29,30]. While subretinal undefined HRM may suggest activity of all CNV subtypes, colocalization of subretinal and intraretinal HRM, along with other tomographic features, may suggest the presence of an active type 3 CNV [15,31] (Figure 3).…”

Clinical Characteristics of Polypoidal Choroidal Vasculopathy and Anti-Vascular Endothelial Growth Factor Treatment Response in Caucasians

“…Polypoidal choroidal vasculopathy (PCV) is a subtype of neovascular age-related macular degeneration (AMD) that can lead to a loss of central vision [1][2][3][4][5]. PCV presents with subretinal leakage and hemorrhage similar to typical exudative AMD.…”

“…PCV presents with subretinal leakage and hemorrhage similar to typical exudative AMD. It is characterized by choroidal neovascularization, with aneurysmal or polypoidal dilations located beneath the retinal pigment epithelium (RPE) and above Bruch's membrane but not in the choroid [1,2,4]. It is a variant of type I subretinal neovascularization [5] and exudative AMD, according to the anatomic classification of subretinal neovascularization supplied by Gass [6].…”

“…PCV has been shown to have a high prevalence up to 62% in Asian patients presenting with signs of exudative AMD [2,7,8]. It was considered relatively uncommon in Caucasian patients [9,10], but with increasing experience in diagnosing PCV, more recent screening with ICGA, and the utilization of the more sensitive scanning laser ophthalmoscope (SLO) [11,12], a significantly higher prevalence is now being reported in this population.…”

Polypoidal Choroidal Vasculopathy: Outer Retinal and Choroidal Changes and Neovascularization Development in the Fellow Eye

“…Therefore, recently, the nomenclature of PCV/aneurysmal type 1 neovascularization (AT1) is suggested to be changed to AT1 neovascularization in an effort to clarifying its true nature. 2,3 PCV/AT1 prevalence is reported to be 22% to 55% in Asians who present with presumed exudative age-related macular degeneration (AMD). [4][5][6][7] The disease has several unique characteristics compared to typical AMD, including younger age at onset and male preponderance.…”