Polypoidal choroidal neovascularization versus Type 1 choroidal neovascularization in age-related macular degeneration

Purpose: To compare quantitative optical coherence tomography angiography (OCTA) parameters between polypoidal choroidal neovascularizations (PCNVs) and Type 1 choroidal neovascularizations (CNVs) in age-related macular degeneration (AMD) patients. Methods: PCNV and Type 1 CNV lesions were retrospectively recruited in a cohort of AMD patients. All underwent a comprehensive ophthalmic evaluation including best corrected visual acuity (BCVA), fluorescein and indocyanine green angiography, structural optical coherence tomography (OCT), and OCTA. Vascular perfusion density (VPD), fractal dimension (FD), and lacunarity (LAC) were computed by means of fractal analysis of neovascular en-face OCTA slabs. Results: 68 eyes were included in the analysis. Of them, 35/68 (51.5%) had PCNV and 33/68 (48.5%) Type 1 CNV. PCNV patients were significantly younger (p=0.0003) and had a higher BCVA (p<0.0001). Mean VPD was 0.83±0.11% in PCNVs and 0.46±0.10% in Type 1 CNVs (p<0.0001). Mean FD was 1.44±0.1 in PCNVs and 1.45±0.09 in type 1 CNVs (p=0.86), while mean LAC was 2.46±1.03 in PCNVs and 1.86±0.52 in Type 1 CNVs (p=0.006). Conclusions: PCNVs resulted to be more heterogeneous and characterized by higher VPD and LAC values than Type 1 CNVs. These interesting findings seem to support the idea that PCNVs and Type 1 CNVs are two separate clinical entities. However, future studies based on OCTA fractal analysis, but also involving other relevant parameters such as demographics, presentation, morphology on multimodal imaging, and response to treatment, are necessary before drawing any definitive conclusions on whether PCNV is a specific clinical entity or a nAMD variant.