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Hematological malignancies may be associated with ocular manifestations in up to 50% of cases, and ocular symptoms can be the initial presentation. Retinal leukemic infiltrates may be observed in up to 3% of leukemia patients. Leukemic retinopathy may present more commonly in acute leukemias than chronic leukemias as Roth’s spot, multi-level retinal hemorrhages, cotton wool spots, or opportunistic infection secondary to pancytopenia. On the other hand, patients with chronic leukemias, such as chronic myeloid leukemia (CML), may present with leukemic retinal infiltrates and venous stasis secondary to hyperviscosity, which may lead to secondary peripheral microaneurysms and neovascularization. Vascular complication, such as central retinal vein occlusion, may also occur as a result of venous stasis. In addition, leukemic retinopathy is associated with poorer overall survival as pediatric CML patients without ocular manifestation may have twice as high 5-years survival rate compared with those with ocular manifestation. The presence of leukemic retinopathy is associated with more severe systemic disease and is correlated with hematological parameters such as white blood cells count (WBC). In addition, a positive correlation was found between ocular leukemic infiltration and agonal leukocyte count and the severity of systemic disease in an autopsy study. Therefore, the presence of retinal infiltrate may be associated with leukemia with extreme leukocytosis. Optical Coherence Tomography (OCT) is a noninvasive retinal imaging tool that can help diagnose leukemic retinopathy. Inner retina hyper-reflective lesions were observed in areas with intra-retinal hemorrhages or hemorrhagic lesions, while outer retina hyper-reflective lesions were observed in areas with whitish retinal infiltrates. In addition, the loss of the physiological hourglass appearance on cross-sectional OCT scan of retinal vessels may be seen in leukemic retinopathy. It is believed that intraluminal blood flow is responsible for the physiological hourglass appearance, consisting of two paired hyper-reflectivities inside vessel wall on OCT. In leukemic retinopathy, hyperviscosity may disrupt normal intraluminal blood flow, leading to the loss of this physiological appearance. In summary, leukemic retinopathy can be the first presentation of leukemia. Ophthalmologists can play an important role in the diagnosis of leukemia. Noninvasive retinal imaging could help us to monitor and understand the pathophysiology of leukemic retinal infiltrates. Prompt diagnosis and treatment of underlying leukemia may preserve vision and prolong survival rate.

Additional file 2: Figure S1. Examples of images showing different morphologies between superficial capillary plexus (SCP, a-c) and deep capillary plexus (DCP, d-f) in diabetic eyes

Additional file 1: Table S1. Comparisons between eyes with/without projection artifacts