Polypoidal Choroidal Vasculopathy in Asians

Abstract

Age related macular degeneration (AMD) in Asians has been suggested to differ from their Western counterparts in terms of epidemiology, pathogenesis, clinical presentation and treatment. In particular, polypoidal choroidal vasculopathy (PCV) appears to be the predominant subtype of exudative AMD in Asian populations, in contrast to choroidal neovascularization secondary to AMD (CNV-AMD) in Western populations. Epidemiological data on PCV has been largely limited to hospital-based studies and there are currently no data on the incidence of PCV. Similarities and differences in risk factor profile between PCV and CNV-AMD point to some shared pathogenic mechanisms but also differential underlying mechanisms leading to the development of each phenotype. Serum biomarkers such as CRP, homocysteine and matrix metalloproteinases suggest underlying inflammation, atherosclerosis and deranged extracellular matrix metabolism as possible pathogenic mechanisms. In addition, recent advances in genome sequencing have revealed differences in genetic determinants of each subtype. While the standard of care for CNV-AMD is anti-vascular endothelial growth factor (VEGF) therapy, photodynamic therapy (PDT) has been the mainstay of treatment for PCV, although long-term visual prognosis remains unsatisfactory. The optimal treatment for PCV requires further clarification, particularly with different types of anti-VEGF agents and possible benefits of reduced fluence PDT.

Keywords: Asians; anti vascular endothelial growth factor; epidemiology; genetics; photodynamic therapy; polypoidal choroidal vasculopathy; risk factors.

Figure 1

Fundus photographs showing the two clinical patterns of polypoidal choroidal vasculopathy: Hemorrhagic (A) and exudative (B). An orange red nodule suggestive of a polyp (white arrow) is seen in an extrafoveal position, while a notch in the hemorrhagic pigment epithelial detachment (white arrowhead) suggests the presence of another polyp.

Figure 2

Angiographic patterns of PCV: Cluster of grapes configuration (A), solitary (B) and string of pearls (C). Branching vascular networks (white arrow) are seen in figure B and C.

Figure 3

Fundal autoflorescence image (A) showing granular hypoautofluorescence, which corresponds to the abnormal branching vascular network seen on indocyanine green angiography (B).

Figure 4

Tomographic features of polypoidal choroidal vasculopathy (PCV): Spectral domain optical coherence tomography (OCT) (A) shows peak like elevation of the RPE with underlying moderate reflectivity within the peak (asterisk), tomographic notch in the PED (white arrow) and double layer sign, consisting of two hyper-reflective lines (white arrowheads). Swept source OCT (B) is able to visualize the underlying thickened choroid (double headed arrow).

Figure 5

Enface swept source optical coherence tomography (OCT) image (B) shows the position of a polyp (white arrow) that corresponds in location to the polyp (intersection of yellow lines) seen on swept source B, scan image (A).