Redness around the eyes when the weather is too hot may be caused by sweat irritation, or it may be caused by diseases such as conjunctivitis and keratitis, as well as other diseases such as blepharitis. 1. Sweat irritation: when the weather is hot, the redness around the eyes may be caused by excessive sweating that irritates the eyes, and if the patient rubs the eyes at this time, it will also cause the redness around the eyes, which will usually be relieved after resting. 2. Conjunctivitis: Conjunctivitis has many causes, including bacterial, viral and chlamydial infections, immune reactions or physical and chemical stimuli. Patients will have symptoms such as red, itchy, painful and dry eyes, as well as symptoms such as papillary hyperplasia and pseudo-ptosis. If the patient has conjunctivitis, there will be redness around the eyes when the weather is too hot. 3. Keratitis: Keratitis is usually caused by viruses, bacteria and other external pathogens or the patient’s own disease, the patient’s main manifestations of eye pain, photophobia, eyelid redness, swelling, purulent discharge, etc., will also appear vision loss, blurred vision and other symptoms. If the patient has keratitis, the phenomenon of redness around the eyes when the weather is too hot can also occur. 4. Other: Blepharitis, blepharitis and other diseases can also cause redness around the eyes in hot weather. If the redness around the eyes is caused by sweat irritation, it does not require special treatment and will usually resolve on its own. If it is caused by a disease, medical treatment is required.