Corneal dry spots are dry corneal spots formed due to the accumulation of corneal epithelium and are mainly seen in vitamin A deficiency disease. This disorder is a systemic nutritional disorder with ocular manifestations of vitamin A deficiency. So how is the disease triggered? 1, improper diet Infants are born with very little vitamin A stored in their liver, which is quickly consumed, but the content in colostrum is very high, human milk and milk is the main source of vitamin A required by infants, other foods such as vegetables, fruits, eggs and liver can supply enough vitamin A. Therefore, a proper diet can supply enough vitamin A without causing deficiency. However, in infancy, simple foods, such as insufficient milk and no supplementation, can easily cause subclinical vitamin A deficiency. After weaning, if the infant is fed with rice cake, batter, rice and fat-free milk for a long period of time without adding protein and fat-rich supplemental foods, it can cause deficiency. 2, digestive system diseases chronic diseases of the digestive system such as long-term diarrhea, chronic dysentery, intestinal tuberculosis, pancreatic disease, etc. can affect the absorption of vitamin A. The liver is the main organ of vitamin A metabolism and storage. The bile acid salt in bile can emulsify lipids and promote the absorption of vitamin A. It can also strengthen the activity of beta-carotene 15,15acute;-oxygenase and promote its conversion into retinol, so vitamin A deficiency is easily caused by diseases of the hepatobiliary system such as congenital biliary atresia and chronic hepatitis. Hepatitis caused by various viruses or toxic hepatitis complicated by infectious diseases can also cause vitamin A deficiency and should be alerted. 3, wasting diseases such as chronic respiratory infectious diseases, prolonged pneumonia, measles, etc., on the basis of insufficient vitamin A intake, symptoms appear due to increased vitamin A consumption. In addition, long-term intake of mineral oil (such as liquid paraffin, etc.), neomycin and methotrexate and other drugs can also affect the absorption of vitamin A. Malignant tumors and urinary tract diseases can increase vitamin A excretion. Protein deficiency affects the synthesis of retinol transporter protein, resulting in a decrease in the attempt of vitamin A in the plasma, which leads to deficiency symptoms. 4.Low thyroid function and diabetes mellitus both can make the process of converting beta;carotene into retinol impaired, resulting in vitamin A deficiency, while the blood and skin accumulate a large amount of carotene, much like jaundice, but the bulbar conjunctiva does not show yellow. 5, zinc deficiency and vitamin A combined with the former albumin and vitamin A reductase are reduced, so that vitamin A can not be used and excreted from the body, vitamin A deficiency can also occur. In recent years, it has been reported that changes in nutritional status also have an effect on the utilization of vitamin A.