In this review, we have summarized the information on the clinicopathologic correlation between bioimaging using optical coherence tomography (OCT) and OCT angiography (OCTA) and histopathological findings related to choroidal neovascularization (CNV), which is important as it is the primary pathology of neovascular maculopathies such as age-related macular degeneration (AMD).
As a basic experiment, a laser-induced CNV model was used, a CNV model that shows extensive growth in mouse eyes. OCTA images of CNV were obtained, and the images were compared with immunohistochemistry images of choroidal flatmount specimens reacted with anti-CD31, anti-PDGFRβ, anti-α-SMA, and anti-collagen typeI antibodies. The results suggested that CNV area is underestimated in OCTA because fibrosis in the periphery of the pericyte-like scaffold of CNV inhibits the detection of CNV using OCTA.
Next, we examined the pathological findings of the excised specimens of polypoidal choroidal vasculopathy (PCV), a disease commonly observed in Japan, and their correlation with OCTA findings of clinically recorded PCV cases. The results suggested that the understanding of the histopathological structure of blood vessels and their surrounding environment is fundamental in the interpretation of OCTA images.
In addition, we examined the OCTA-related pathologic correlation of type2 CNV with exudative AMD. We found that there are two subtypes of type2 CNV: one type showing dense capillary proliferation under the retina (capillary-growing type) and the other type with relatively thick blood vessels growing in the form of a loop under the retina (looped blood vessel type). In particular, the latter is considered type2 CNV derived from PCV.
Lastly, we verified the correlation between choroidal OCT and the histopathology of the pachychoroid spectrum of diseases with choroidal thickening and found that choroidal venous dilation and choriocapillaris dropout are involved in the pathological condition. The pathogenesis of PCV has been discussed based on the results.
Through this review, we emphasize that an ophthalmic pathological understanding of diseases and pathological conditions is imperative for accurate interpretation of CNV images obtained using OCT/OCTA, thereby facilitating more reliable diagnosis and treatment.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 123: 284-311, 2019.