Abstract:Fractals refer to structures whose component parts exhibit similarity to the whole in certain aspects. The retinal microvascular system, as the only terminal microvasculature that can be directly observed in vivo, possesses a tree-like branching morphology that conforms to the characteristics of fractals. Fractal dimension(FD)is a numerical value that describes the density and complexity of the overall retinal vascular network, complementing the limitations of vessel density alone in characterizing vascular structural features. In recent years, the widespread application of optical coherence tomography angiography(OCTA)has enabled the visualization of blood flow across various retinal capillary layers, thereby extending the concept of fractal analysis to the retinal microvasculature. FD has been demonstrated to serve as a novel potential biomarker for ophthalmic conditions, including diabetic retinopathy, glaucoma, age-related macular degeneration, high myopia, and retinal vein occlusion, providing valuable metrics for the early diagnosis of these diseases. This review provides a comprehensive summary of the definition, calculation methods, influencing factors, and recent research developments regarding FD in various ophthalmic disorders.
