There is a relationship between poorer vision and the liver, mainly related to vitamin A, which is an important substance needed by the optic rod cells. If the human liver functions abnormally, such as viral liver damage, drug-induced cirrhosis, alcoholic cirrhosis, cholelithiasis, obstructive jaundice, etc., the liver’s ability to process vitamin A is affected, which in turn causes the patient to develop night blindness. Thus, night blindness is usually due to the inability of the optic rod cells to obtain vitamin A efficiently. Normally, the role of the optic rod cells is to enable the body to distinguish things in the dark and then process the observed image, including the size of the outline. However, the optic rod cells are unable to process color, which results in a black and white image at night.