If a 7-year-old child is deficient in vitamin D, he or she will often have the following symptoms. First, it can cause dry skin because vitamin A helps the integrity of the skin mucosa, and children with vitamin D deficiency tend to have particularly dry skin. Secondly, it can cause night blindness, which means that children have very poor dark vision and can see very poorly at night in low light conditions. This can affect the quality of life of children, and after vitamin D deficiency occurs, vitamin D should be supplemented in a timely manner, such as applying vitamin AD drops.