6-year-old Dudu’s eyes are itchy these days, but also often runny eyes, point home eye drops but no improvement, but the eyes are red. Mom and dad are worried that he has red eyes, so they took him to the hospital. The ophthalmologist learned that, since the age of 4, every year in April and May will appear this situation, sometimes also itchy nose, sneezing, and previously had allergic asthma. The doctor turned over Dudu’s upper eyelids and found that the conjunctival surface had many large and small red protrusions, much like the old Shanghai “popping grids”, and the whites of the eyes were also a bit yellowish. The doctor said that Dudu had an allergic eye disease called “spring catarrhal conjunctivitis”. April and May is the time of spring, but various allergens are also unknowingly attacking human health. In the past few days, there has been a significant increase in the number of patients with allergic conjunctivitis coming to the ophthalmology clinic, many of whom are children like Dodo. Allergic conjunctivitis is an inflammatory eye disease in which the conjunctiva has a hypersensitive immune response to external allergens, most often in children and adolescents. The former is a type I reaction, mainly mediated by antibodies, while the latter is a type IV reaction, mainly mediated by sensitizing lymphocytes. Clinically, there are five subtypes of allergic conjunctivitis: seasonal conjunctivitis, perennial conjunctivitis, spring catarrhal conjunctivitis, atopic keratoconjunctivitis, and giant papillary keratoconjunctivitis. Because the conjunctiva is exposed, it is therefore susceptible to contact with airborne allergens. There are many allergens that cause allergic conjunctivitis, including exposure to pollen, dust mites, and animal feathers, infection with bacteria and other microorganisms, use of allergic eye medications, and consumption of foreign animal proteins. The mechanism of most allergic conjunctivitis is that allergens cause sensitization of lymphocytes in the body, producing antibodies to IgE, which come into contact with mast cells in the body, causing the latter to degranulate and release histamine, an inflammatory mediator, from the cells, which then acts on the capillary wall, increasing the permeability of the vessel wall and causing fluid and protein to leak out of the vessel into the bloodstream. The histamine then acts on the capillary wall, increasing the permeability of the vessel wall, and the fluid and protein inside the vessel leak out into the tissue, causing allergy. The main symptom of allergic conjunctivitis is itchy eyes, even unbearable itching, and constant rubbing of the eyes. This may sometimes be accompanied by photophobia, tearing and foreign body sensation. Eye examination may reveal bulbar conjunctival edema, commonly known as “blistering eyes”, conjunctival congestion, and lid conjunctiva with papillae and follicles of varying sizes due to lymphatic tissue hyperplasia. After repeated episodes of allergic conjunctivitis, the color of the bulbar conjunctiva and corneal rim may become smeared. Prevention of allergic conjunctivitis should be the main focus. Young parents should take good care of their children, especially those with allergies, and should not take them lightly. Don’t touch puppies and cats, flowers and plants, and try to eat less seafood and animal protein. Once you have the disease, use medication under the guidance of your doctor and never abuse antibacterial drugs. There are several ways to deal with allergic conjunctivitis: 1. Use cold compresses, preferably ice. This will make the local blood vessels constrict, reduce the leakage of intravascular substances and reduce the symptoms. Do not apply hot compresses, otherwise it will only aggravate the symptoms. Nor can you wash your eyes with salt water. 2. Use vasoconstrictor drops. 3. Use glucocorticoid drops. Can be used in the acute stage. It should not be used for a long time to prevent hormonal glaucoma and increase in intraocular pressure. 4. Mast cell membrane stabilizer. 5. Antihistamine drops.