抗血管內皮生長因子於息肉狀脈絡膜血管病變的應用

Anti-vascular Endothelial Growth Factor for Polypoidal Choroidal Vasculopathy

息肉狀脈絡膜血管病變可以被視為年齡相關性黃斑部病變的一種特殊類型，並且非常好發於亞洲人種，包括臺灣。其特色為眼底檢查時可見到橙色深處突出之結癤，有時並伴隨有一些滲出斑或出血斑。於循血綠螢光血管攝影圖中，特別可見到亮白呈現高螢光顯影之血管瘤狀或息肉狀之血管囊腫，並伴隨有一些分支血管網絡。近年來，抗血管內皮生長因子已經取代光動力療法而成為治療年齡相關性黃斑部病變的主流方法，然而，目前仍無足夠證據顯示抗血管內皮生長因子比光動力療法更能有效治療息肉狀脈絡膜血管病變。唯一可歸為實證醫學層級第1 級的研究為EVERST study 為期6 個月的短期研究。研究結果，無論單一光動力療法或合併光動力療法與抗血管內皮生長因子皆較單一抗血管內皮生長因子更能有效將息肉狀病灶加以閉鎖；但另一方面，它也顯示使用單一抗血管內皮生長因子治療息肉狀脈絡膜血管病變6 個月後能有效提昇病患之最佳矯正視力達9.2 個字母。其他較長期的研究則多半屬於實證醫學層級歸類為較低層級的研究。其中多數的研究亦顯示雖然單一抗血管內皮生長因子不能十分有效的將息肉狀病灶加以閉鎖，但仍能有效的減少其視網膜下液體的積蓄而有助於視力的進步。另外一些研究則顯示抗血管內皮生長因子對於一些「息肉狀病灶雖然已被閉鎖後，殘留的分支血管網絡仍繼續滲漏」的病患特別有效。綜合多數研究結果可以推得治療息肉狀病灶與滲漏型分支血管網絡似乎應使用不同的治療策略，即息肉狀病灶應用光動力療法或雷射加以閉鎖，而滲漏型分支血管網絡則使用抗血管內皮生長因子加以治療，這種合併療法可能是目前已知最佳的息肉狀脈絡膜血管病變之治療策略。

Polypoidal choroidal vasculopathy is a unique type of age-related macular degeneration that is very prevalent in Asian people including Taiwan. It is characterized by the presence of polypoidal appearance of focal hyperfluorescence in the early phase of indocyanine green angiography (ICGA) and may also be associated with a branching vascular network (BVN) and clinically visible orange-red subretinal nodule(s). Recently, a paradigm shift of using anti-VEGF instead of photodynamic therapy (PDT) has been a common practice in treating typical AMD. However, there is still lack of enough evidence suggesting that anti-vascular endothelial growth factor (anti-VEGF) is superior to PDT for the treatment of PCV. The only evidence based medicine (EBM) level-1 study investing this topic is a short term (6-months) study "EVERST". It showed that both PDT alone or in combination with anti-VEGF were superior to anti-VEGF alone in terms of total regression of polyps. However, it also showed that the best corrected visual acuity (BCVA) in 6 months follow up increased for 9.2 letters in the anti-VEGF alone group. Other longer term studies all belong to lower EBV levels. Most of the studies revealed that although anti-VEGF alone could not achieve a high rate of complete regression of polyps, it is still effective in regressing the subretinal fluid in the OCT examination and can therefore improve the visual function to some degree. Several studies also revealed that anti-VEGF is particularly useful for those PCV patients with persistent leaking BVN despite all the visible polyps have been ablated. After reviewing the current studies in the literature, it seems appropriate to conclude that there should be different strategies for the treatment of polyps and the associated BVN or CNV. The combination of ablative treatment for the polyp (PDT or laser) and the anti-VEGF treatment for the leaking BVN seems to be the optimal strategy for the treatment of PCV.