Red eyes with eye boogers on one side may be caused by conjunctivitis, keratitis and dacryocystitis. 1. Conjunctivitis: Conjunctivitis is a common inflammatory disease of the conjunctival tissue, usually caused by infection, allergy, physical and chemical stimulation, etc. Children may have conjunctival congestion, photophobia, tearing, increased eye secretions and other uncomfortable symptoms. 2. Dacryocystitis: If the child has tear duct obstruction and secondary infection, dacryocystitis can occur, under the stimulation of inflammation, the patient may appear photophobia, tearing, conjunctival congestion and other discomforts, extrusion of the lacrimal sac area can also appear in the corners of the eyes with pus, so that the child’s corners of the eyes with more eye droppings. 3. Keratitis: Keratitis is caused by bacterial, fungal and other infections, and children may experience conjunctival congestion, photophobia, tearing, blurred vision, increased ocular secretions and other discomforts. It is recommended that patients with red eyes and other discomforts should consult a doctor in a timely manner to identify the cause of the disease and choose the appropriate treatment under the guidance of the doctor.