“…SD-OCT can identify the retina's cholesterol crystal structures as hyperreflective crystalline deposits (HCDs) or the onion sign [ [85] , [86] , [87] ]. Horizontal HCDs in diabetic patients suggest cholesterol crystals in retinal hard exudates [ 88 ]. Thus, HCDs or CCs can be a biomarker for imbalanced cholesterol metabolism and DR [ 88 , 89 ].…”