GFAP and vascular disorder: This may lead to differences in the main areas of damage and the severity of optic nerve damage between the two diseases, resulting in differences in the patient's retinal structure, further leading to differences in the degree of secondary retinal vascular changes in each disease; (3) The difference in retinal VD between the two diseases may be due to different pathophysiologic mechanisms that trigger the primary vasculopathy; (4) NMOSD results in the loss of perivascular GFAP-positive astrocytes [172], whereas previous studies have found that GFAP is generally upregulated in MS [173].