The term mydriasis, clinically known as blepharitis, refers to a purulent inflammation of the lid gland tissue. If the sebaceous or sweat glands of the eyelid are infected, it is called exophthalmos; if only the lid glands are involved, it is called endophthalmos. In the case of exophthalmos, it usually presents as a localized redness and swelling of the eye with significant pain, usually followed a few days later by a yellow pus head at the base of the eyelashes. If the pus head has formed, an incision can be made to drain the pus, usually parallel to the lid margin, on the skin surface. In the case of internal mydriasis, the degree of redness may be less than that of external mydriasis, but the pain is more severe, and the yellow pus head can sometimes be faintly seen under the congested conjunctival surface before the abscess has penetrated. Therefore, early on, hot compresses on the eyelids as well as antibiotic eye drops and ointments for the conjunctival sac and systemic antibiotic medications are also considered. When a yellow pustule appears, the pus should be opened in a timely manner in the hospital, and the incision should generally be perpendicular to the lid margin to avoid damaging too many lid glands. Therefore, if you notice significant redness and pain in the eyelid, it is better to go to the hospital in time and get symptomatic treatment.