Allergic conjunctivitis is the most common type of allergic eye disease and is mainly caused by type I allergic reactions. There are 5 types of allergic conjunctivitis depending on clinical manifestations, course and prognosis. Seasonal allergic conjunctivitis, also known as chytridiogenic conjunctivitis, is the most common clinical type. The allergen is mainly pollen. It is seasonal (usually in spring). The onset is rapid in both eyes, and the symptoms are relieved soon after the allergen is removed. 2. Perennial allergic conjunctivitis Allergens are dust, animal feathers, fur, insect mites, cotton and linen. Symptoms persist year-round and can be seasonally aggravated. 3, spring keratoconjunctivitis, also known as spring khat or spring conjunctivitis. Allergens are pollen, dust, animal fur, antigenic components of various microorganisms and sunlight. It often occurs in dry, hot or heavily polluted areas in spring and summer. It is more common in boys with a personal or family history of allergy, with the first occurrence under 10 years of age. 4. Giant papillary conjunctivitis associated with microtrauma and antigen deposition. Most commonly seen in patients with corneal contact lenses or prosthetic eyes, history of corneal surgery (unburied), retinal detachment surgery (filler exposure). 5, atopic keratoconjunctivitis is less common, chronic, and relatively severe. The allergens are mostly unclear and are closely related to genetics. Most often occurs in middle-aged men between the ages of 30 and 50. Symptoms The most common symptom is itchy eyes, the degree of which varies by type, with conjunctivitis being the most pronounced in spring. This is followed by lacrimation, burning sensation, photophobia and increased mucus filiform discharge. Spring conjunctivitis and atopic conjunctivitis sometimes present with decreased vision. Seasonal allergic conjunctivitis is often accompanied by symptoms of respiratory mucosal epithelial allergy. Treatment 1. General treatment (1) Removal from allergens: Try to avoid contact with possible allergens. (2) Cold compresses for the eyes: can temporarily relieve symptoms. Wear dark-colored glasses to reduce sunlight stimulation. Avoid rubbing the eyes to avoid mast cell degradation and corneal epithelial damage. 2, drug treatment (1) antihistamines: commonly used eye drops are 011% emetine, 0105% levocabastine (Lefoxitin), 015% ketorolac ammonia. If there are extra-ocular symptoms, they can be used orally, but the effect is not as good as local medication. In addition, systemic use can cause cholinergic symptoms or sedation, so special attention should be paid to patients who are engaged in driving, working at height, etc. They are usually best used at night before bedtime. Commonly used are Benadryl, paracetamol, promethazine, etc. The combination of antihistamines and vasoconstrictors can have a better effect. Commonly used eye drops include R&J and Nasuada. (2) mast cell stabilizers: by inhibiting cell membrane calcium channels, prevent the release of inflammatory mediators caused by the binding of antigen and IgE on the mast cell membrane. Commonly used colored glycolic acid disodium and nedolomide. Less effective overall than antihistamines, but more effective in suppressing tearing. They are less effective in patients who have had an attack and are best used before exposure to allergens. (3) Non-steroidal anti-inflammatory drugs: they are cyclooxygenase inhibitors, which inhibit the production of prostaglandins and the chemotaxis of eosinophils. They can be used in both acute and intermittent phases. Commonly used eye drops include Diflucan and Pernambuline. Oral drugs include anti-inflammatory pain (diclofenac sodium), aspirin, etc. However, oral administration should pay attention to side effects such as gastric ulcer and bleeding. (4) vasoconstrictors: local use to improve eye discomfort and reduce congestion. However, long-term use is not recommended. (5) Glucocorticoids: Glucocorticoids are usually used short-term in severe allergic conjunctivitis when other drugs are ineffective to avoid complications such as cataracts, increased intraocular pressure, and delayed corneal epithelial healing. Commonly used eye drops are dexamethasone, flutemetron, etc. (6) Immunosuppressants: mainly cyclosporine A and tacrolimus. They are mainly used for severe allergic conjunctivitis that requires hormone therapy, and can quickly control local inflammation and reduce hormone dosage. However, it often relapses after 2-4 months of discontinuation. 3. Desensitization therapy is mainly used for seasonal allergic conjunctivitis, but is not effective for other types of allergic conjunctivitis. Prognosis The prognosis of seasonal allergic conjunctivitis, perennial allergic conjunctivitis, and giant papillary conjunctivitis is good, and complications rarely occur. Springtime keratoconjunctivitis is self-limiting and often resolves spontaneously after 5-8 years of onset (adolescence). Common complications include bacterial infection of the cornea and corneal clouding causing astigmatism and cone corneas. Common complications of ectopic keratoconjunctivitis include bacterial infection of the cornea, herpes moniliformis infection, and cone keratoconus.