Polypoidal Choroidal Vasculopathy—An Important Diagnosis to Make with Therapeutic Implications

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Polypoidal choroidal vasculopathy (PCV) is an increasingly recognized cause of exudative and hemorrhagic complications in the macula.1–3 This exudative maculopathy mimics all the findings of exudative age-related macular degeneration (AMD) on clinical examination and fluorescein angiography. Indocyanine green (ICG) angiography is required to accurately identify PCV, which manifests as hyperfluorescent polypoidal lesions with or without a visible branching vascular network.4Although recent discussion has focused on whether ICG angiography is still relevant,5 ICG angiography remains necessary and essential for the diagnosis and management of PCV.4,5 Even though a widely accepted criterion for the definition of PCV based on ICG angiography is yet to be developed, the need for ICG angiography to make the diagnosis of PCV is widely accepted. Despite this widespread acceptance of ICG angiography to diagnose PCV, ICG angiography is not widely used in many countries, except in Asian countries, where PCV prevalence is especially high.Polypoidal choroidal vasculopathy occurs in all ethnic groups, including white populations,6,7 although it is seen more commonly in Asian8,9 and African American populations.10 Because it occurs in all populations, PCV would be more frequently diagnosed with increased use of ICG angiography in all patient populations. Because ICG is not routinely done in white populations, the true incidence of PCV in whites is still unknown, although it is suspected to be higher than previously reported.Although it is controversial whether PCV is a choroidal vascular abnormality, or whether PCV is a type of subretinal neovascularization,3,7,11 recently there is increasing evidence that PCV is a type of subretinal neovascularization growing between the retinal pigment epithelium (RPE) and Bruch membrane or within Bruch membrane.11 This represents a variant of type I subretinal neovascularization, as previously defined by Gass12 and more recently updated by Freund et al.11 Histopathology has also confirmed that PCV represents large, thin-walled, cavernous vascular channels with accompanying choroidal neovascularization within Bruch membrane and underneath the RPE.13,14En face optical coherence tomography studies have shown that polypoidal choroidal vasculopathy results in small round protrusions of the RPE, while the branching vascular network induces slight elevation of the RPE from the underlying Bruch membrane.15 C-scan en face spectral optical coherence tomography has shown that PCV lesions are often contiguous with subretinal neovascularization located between the RPE and Bruch membrane.7 Since the PCV vessels are beneath the RPE, and also are more mature vascular structures than choroidal neovascularization associated with exudative AMD, this may have implications in regards to the response to different therapeutic modalities.In a recent issue of Retina, Koh et al16 found in a randomized controlled clinical trial (EVEREST study) a much higher polyp closure rate with photodynamic therapy (PDT), or combined PDT and ranibizumab, when compared with ranibizumab monotherapy alone. These findings highlight the importance of making the diagnosis of PCV with ICG angiography, as PDT may represent an important part of the therapeutic regimen for PCV. In addition, in the EVEREST study, ICG angiography actually guides therapy with PDT, as it was used to show the location of the polypoidal vessels and to minimize spot size by localizing PDT only to the area of the PCV vessels on ICG angiography.Diagnosing PCV may also be important for evaluating and guiding therapy outside of PDT. Antiangiogenic therapy with anti–vascular endothelial growth factor (anti-VEGF) drugs has become the mainstay of treatment for exudative AMD, resulting in significantly improved visual and anatomical results than any previously available therapy. Treatment for PCV with anti-VEGF drugs has been studied with bevacizumab and ranibizumab.

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