The types of conjunctivitis classified according to etiology include bacterial conjunctivitis, viral conjunctivitis, chlamydial conjunctivitis, and immunologic conjunctivitis. Differential diagnosis is mainly made from symptoms and pathogenetic tests. 1. Bacterial conjunctivitis: mainly characterized by catarrhal or mucopurulent exudate, monocular onset, can be spread to both eyes by hand touching, the patient can feel eye irritation and congestion, at first there is no manifestation of vision loss, with the development of the disease can cause vision loss. Secretion smear or conjunctival scraping and other examinations can see a large number of polymorphonuclear leukocytes and bacteria. 2. Viral conjunctivitis: it is a highly infectious contact infection, mainly caused by adenovirus, with acute onset, severe symptoms, bilateral onset, watery secretion, subepithelial infiltration of the cornea is a typical feature of the disease, and conjunctival scraping reveals a large number of mononuclear cells, and when there is pseudomembrane formation, the number of neutrophils increases. Other tests such as virus culture can help in the diagnosis. 3. Chlamydial conjunctivitis: trachoma initially manifests as follicular chronic conjunctivitis, acute symptoms include photophobia, lachrymation, foreign body sensation, no obvious discomfort in the chronic phase, only itchy eyes, conjunctival congestion is mild, trachoma cytology is typically characterized by the detection of lymphocytes, plasma cells, and polymorphonuclear leukocytes, but cytology has a high false-positive rate. 4. Immune conjunctivitis: common for allergic conjunctivitis, most have a history of allergen exposure, the prognosis is good, usually no visual impairment. No matter which kind of conjunctivitis should be timely treatment, under the guidance of the doctor to use drugs, daily attention to eye protection.