The diagnosis is not difficult when the eye has obvious dry spots on the cornea, combined with a history of feeding, chronic digestive or wasting diseases. Because vitamin A deficiency is often associated with comorbidities, any child with malnutrition, chronic diarrhea, chronic dysentery, or long-term mouth avoidance after measles and photophobia and blinking should be carefully examined for ocular changes. Older children should be noted for skin changes. In early and atypical cases, the ocular changes are mild and easily overlooked, especially in infancy. The following tests can be done to help diagnose suspicious cases: 1. Use a small cotton swab dipped in saline to gently scrape off a small amount of material from the conjunctival surface, and keratinous epithelial cells can be seen under the microscope; 2. Serum vitamin A determination is the most reliable indicator. Take about 10mg of fresh middle urine plus several drops of 1% gentian violet solution, shake well, and do epithelial cell count. Each cubic millimeter of normal urine contains at most 3 epithelial cells; more than 3 can indicate vitamin A deficiency in addition to urinary tract inflammation. The degree of keratinous degeneration of epithelial cells can be measured by examining urine sediment with a high-powered microscope. If there is a deficiency of vitamin A in the food or an impaired absorption, symptoms may appear within a few weeks. Young infants with congenital biliary obstruction, infantile hepatitis syndrome, and if complicated by pneumonia may develop ocular dryness within a short period of time and should be noted early.