Combining Hypo-Reflective Structural En Face Imaging Improves Polypoidal Lesion Detection on Spectral-Domain OCT Angiography

The purpose of this study was to identify novel features on spectral-domain optical coherence tomography angiography (SD-OCTA) that improve detection of polypoidal lesions in polypoidal choroidal vasculopathy (PCV). In this prospective study, 22 eyes from 20 patients with indocyanine green angiography (ICGA) confirmed PCV underwent same-day imaging with both SD-OCTA and swept-source OCTA (SS-OCTA). Images were independently reviewed, and blinded to ICGA and each other. Morphological features of polypoidal lesions were compared to establish combined diagnostic criteria to improve SD-OCTA detection, including hyper- or hypo-flow signals on angiographic en face images, circular hypo-reflective signals on structural en face images, and corresponding flow signals within retinal pigment epithelial detachments (PEDs) on B-scans. Hyporeflective signals on structural en face images were defined as well-circumscribed and low-reflectivity areas. Diagnostic accuracy was assessed using sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve (AUC). ICGA identified 52 polypoidal lesions. SS-OCTA showed superior detection (98%) compared to SD-OCTA (69%) after manual segmentation correction. Hyporeflective signals on SD-OCTA structural en face images were observed in 73% of lesions, higher than SS-OCTA (52%). Applying combined criteria to SD-OCTA enabled detection of 8 additional lesions, raising the detection rate to 85% and diagnostic accuracy to 95%. This combined approach significantly improves SD-OCTA diagnostic performance and is recommended in clinical practice, especially when standard retinal pigment epithelium (RPE) and Bruch's membrane (BM) segmentations were used. Identifying hyporeflective signals on structural en face SD-OCTA improves polypoidal lesion detection, enhancing the clinical utility of SD-OCTA in diagnosing PCV.