The appearance of thread-like eye droppings is due to the conjunctival sac of the eye in the secretion is more viscous, condensed into a filamentous form and caused, mainly due to the following diseases: first, is caused by chronic dacryocystitis, due to the nasolacrimal duct part of the blockage, the tear drainage to the lacrimal sac can not continue to be discharged, and stagnant in the lacrimal sac, the water is gradually absorbed by the mucous epithelium of the lacrimal sac, which is condensed into a sticky The water is gradually absorbed by the mucosal epithelium of the lacrimal sac, thus condensing into a viscous secretion and flowing back into the conjunctival sac through the lacrimal punctum and lacrimal ducts, thus forming thread-like eye droppings; secondly, it is due to allergic conjunctivitis, when the conjunctival tissues come into contact with allergens, a large amount of mucous exudate will be formed, thus forming thread-like eye droppings; thirdly, it is due to chronic conjunctivitis, which is related to the stimulation of conjunctival tissues by air pollution and a small amount of thread-like secretion will appear in the conjunctival sac.