An analysis of caliber-specific blood flow path length in optical coherence tomography angiography using morphological top-hat transform

Optical coherence tomography angiography has a function to visualize the blood flow of multi-layered retinal capillary plexus by layer. OCTA signals would be more utilized if they are associated with blood flow dynamics of each layer. In this study, morphological top-hat transform was applied for OCTA en face retinal images of superficial and deep layers obtained from patients of diabetic retinopathy and controls to quantify the caliber-specific flow path length. As a result, the total length of the thick flow paths in deep layer more strongly reflected the progress of retinopathy than that in superficial layer. Supposing the thick flow paths observed in deep layer OCTA as a superposition of multiple capillaries, this trend seemed to be a possible expression of partial clogs of the capillary network.