Conjunctivitis can be typed according to the duration of the disease, which can be classified as hyperacute, acute or subacute, and chronic, usually less than three weeks for acute conjunctivitis and more than three weeks for chronic conjunctivitis. It can also be classified according to etiology as infectious, immunologic, chemical or irritant, systemic disease related, secondary, and unexplained conjunctivitis. Clinically, because of the simplicity of diagnosis required, the diagnosis is usually made based on the basic condition of inflammation, signs, and usually no laboratory tests are done. If the exact disease is severe or persistent, pathogenic tests may be performed. If the discharge from the conjunctiva is mucoid or purulent, bacterial infection is usually considered, if it is mucoid and filmy, allergic conjunctivitis is considered, and aqueous or plasma-like discharge is considered viral conjunctivitis. Others, such as the presence of some true membranes, pseudomembranes or subconjunctival hemorrhages, and enlarged preauricular lymph nodes, suggest the possibility of viral conjunctivitis.