Comparison between non-visualized polyps and visualized polyps on optical coherence tomography angiography in polypoidal choroidal vasculopathy

Purpose To determine the underlying reasons for the non-visualization of polyps on en face optical coherence tomography angiography (OCTA) in patients with polypoidal choroidal vasculopathy (PCV). Methods A cross-sectional study of consecutive treatment-naive 30 eyes with active PCV was included. Results of fundus photography, fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), spectral domain optical coherence tomography (SD-OCT), and en face OCTA were analyzed. Results A total of 64 active polyps were found on FFA and ICGA in 30 eyes. On OCTA, 42/64 (65.6%) polyps were visualized, while 22/64 (34.4%) polyps were non-visualized. There were no significant differences in the size (P = 0.723) and filling time of polyps (P = 0.558) between the two groups. However, polypoidal lesions were less common in the non-visualized group (P < 0.001). The height of the polyps on SD-OCT was 243.95 +/- 114.24 mu m in the non-visualized group, which was higher than those (188.00 +/- 87.93 mu m) in the visualized group (P = 0.048). Moreover, more pulsatile polyps (72.7%) were found in the non-visualized group than those (2.4%) in the visualized group (P < 0.001). Four of the 22 polyps in the non-visualized group (18.2%) were located under a thick subretinal hemorrhage, and two of 22 invisible polyps (9.6%) located under and parallel to the retinal vessel in the inner layer of retina. Conclusions Our results revealed that the height of the polyps, and not the size and pulsation of the polyps, correlated with the visualization of the polyps on OCTA. Polyps that were pulsating in early ICGA were difficult to be visualized on OCTA, which is the most possible reason for the non-visualization. Coverage with thick subretinal hemorrhage or retina vessels was another reason for the non-visualization of the polyps in active PCV on OCTA.