It is every parent’s dream to have a smart and beautiful child, and eyes are the windows to the soul, and a child with big, watery eyes is really endearing. But, are big, watery eyes always beautiful? In fact, if your child’s eyes are always “watery”, you should be alerted to the fact that your child may have a disease – tear duct obstruction. So what is tear duct obstruction? What are the causes of tear duct obstruction in children? During the embryonic period, there is a semilunar valve (Hasner’s membrane) at the end of the nasolacrimal duct. After birth, this membrane will rupture automatically when tears are produced and tears will flow smoothly into the nasal cavity along the nasolacrimal duct, but there are a few newborns who are born with a thicker membrane and fail to rupture on their own after birth, or due to congenital narrowing of the nasolacrimal duct or nasal septum malformation, tears cannot drain normally into the nasal cavity through the lacrimal drainage system. Tear overflow occurs due to congenital narrowing of the nasolacrimal duct or nasal septal malformation. Tears long-term retention in the tear sac, become a base for bacterial reproduction, over time, resulting in chronic dacryocystitis, and even dacryocystitis, when the inflammation repeatedly stimulate the mucosa of the tear duct, resulting in thickening of the mucosa, thus making the slender tear duct more narrow; in addition, the tear sac with thick fluid hanging in the eye, as if a time bomb, once the eye has trauma, germs immediately take advantage of the situation, the consequences are unimaginable. Therefore, when the child does not cry but also tears, parents should promptly take the child to the hospital, early lacrimal duct flushing may break through Hasner’s membrane and cure, if the flushing does not pass, then to perform lacrimal duct exploratory surgery. However, many parents have concerns because their children are too young, but in fact, early treatment is more curable, and once severe obstruction is formed, resulting in stubborn lacrimal stenosis, treatment is difficult and the failure rate and recurrence rate is high. If your child has “big watery eyes”, he or she may also have another disease, congenital glaucoma. This is a disease that can seriously damage the vision of infants and children. If not treated early, it can cause irreversible damage to the child, resulting in lifelong disability. Children with congenital glaucoma show signs of photophobia and tearing at an early stage, and their eyes gradually become larger, but these are often overlooked by parents, and most of the children who visit the hospital have developed into advanced stages. Even if surgery is performed, it is only to control the progression of the disease. Furthermore, the earlier the onset of glaucoma in infants and children, the worse the surgical outcome, requiring a long-term collaborative relationship between parents and doctors to treat the child for life. Therefore, when a child has “big watery eyes”, parents should not be complacent, but should observe whether the child is tearing even when he or she is not crying, whether the eyeball or black eye is bigger than children of the same age, and whether he or she is always afraid of light. When your child has these symptoms, be sure to go to the hospital as soon as possible for examination and early diagnosis and treatment.