Conjunctivitis is divided into two categories: infectious and non-infectious. Infectious conjunctivitis includes bacterial, viral and chlamydial infections, etc. Treatment is mainly based on the pathogen, with supportive treatment such as artificial tears if necessary. 1. Bacterial conjunctivitis. The main features are significant conjunctival congestion and mucopurulent discharge, and the pathogenic microorganisms are Staphylococcus, Streptococcus pneumoniae, Haemophilus influenzae, etc. Antibiotics commonly used in bacterial conjunctivitis include aminoglycosides (e.g., gentamicin, neomycin, tobramycin, etc.), fluoroquinolones (e.g., gatifloxacin, norfloxacin, ofloxacin, etc.), aminoglycosides (e.g., chloramphenicol), tetracyclines, macrolides (e.g., erythromycin, rifampin), etc. When the etiology of the first treatment is unclear, broad-spectrum antibiotics should be preferred, and the combination of different types of antibiotics, taking into account both cocci and bacilli, should be used mainly locally, and in severe cases, drugs should be used according to the drug sensitivity test of the causative agent. However, there are limitations of antibacterial ophthalmic drugs, and the increase of bacterial resistance due to the widespread use of broad-spectrum antimicrobials and the pharmacokinetic defects of the antimicrobial drugs themselves has become the primary problem, how to increase the affinity of drugs, reduce the number of doses to reduce side effects and increase the efficacy of drugs is the current problem faced by ophthalmic antimicrobial drugs. 2. Viral conjunctivitis. Can be caused by adenovirus, herpes simplex virus and varicella-zoster virus. Patients with severe viral conjunctivitis may complain of significant photophobia and foreign body sensation, and the patient’s conjunctival surface may have fibrinous pseudomembranes and inflammatory cells and/or focal corneal inflammation. Treatment in the acute phase may include antiviral drugs to inhibit viral replication such as interferon eye drops, 0.1% acyclovir ophthalmic solution, and ganciclovir ophthalmic gel. Antibacterial ophthalmic solutions are added in case of combined bacterial infection. In case of severe pseudomembranes, corticosteroid eye solution can be considered, but the side effects of corticosteroids should be closely monitored, such as increased intraocular pressure and aggravation of viral infection. 3, Chlamydia infection. 15% sodium sulfacetamide or 0.1% rifampin ophthalmic solution can be used. Non-infectious conjunctivitis is closely related to the immune response, and is commonly seen in clinical settings such as humoral immune-mediated spring conjunctivitis, allergic conjunctivitis, cellular immune-mediated vesicular conjunctivitis, and autoimmune diseases such as dry keratoconjunctivitis, conjunctival aspergillosis, Stevens-Johnson syndrome, etc. For spring conjunctivitis, corticosteroid ophthalmic solution can be used frequently (every two hours) for 5-7 days in the acute phase and rapidly reduced after improvement. Mast cell stabilizers (sodium cromoglycate), antihistamines (emetine) and Patanlo ophthalmic solution which has both mast cell stabilization and antihistamine effects. In recalcitrant cases with significant symptoms despite treatment with the above drugs, 2% cyclosporine eye drops can be used, which can often control the symptoms quickly but can have a tendency to relapse after 2-4 months of discontinuation. The principles of local ocular medication for allergic conjunctivitis are the same as for spring conjunctivitis, except that allergens are sought and avoided. Treatment of vesicular conjunctivitis is primarily with corticosteroid ophthalmic solutions. Autoimmune conjunctivitis is treated with immunosuppressive agents such as cyclosporine ophthalmic solution and artificial tears. Corticosteroids should be used with caution, close attention to intraocular pressure and prevention of corneal lysis and perforation.