Chalazion and mydriasis are two common eye diseases, but many people do not distinguish between them and confuse them, in which case they naturally do not receive timely and effective treatment, making a very simple problem very complicated, affecting the treatment not only, but also making themselves suffer more. The medical name for this is blepharitis. It is a purulent inflammation of the eyelid glands in the eye caused by infection with the bacteria Staphylococcus aureus. It usually develops with redness, swelling, heat, and pain. When the redness is located mainly on the skin surface and the abscess penetrates on the skin surface, it is external chalazion; while when the redness is located on the conjunctival surface or the abscess penetrates the conjunctiva, it is internal blepharitis. Chalazion, also known as a chalazion cyst, is medically defined as an aseptic chronic granulomatous inflammation caused by obstruction of the lid gland ducts and retention of glandular secretions in the lid, usually with a fibrous connective tissue envelope. It is most common in adolescents or middle-aged adults, and is caused by the high secretion of the lid glands at that age. The typical presentation is a palpable tough lump on the lid, located subcutaneously, within 5 mm of the lid margin, that is not red or painful, with elevated surface skin and limited dark red or purplish congestion on the corresponding conjunctival surface. Now that we know what chalazion and mydriasis are and their triggers and symptoms, how should they be distinguished from each other? The biggest difference between them is that the onset of chalazion is more acute, with heavy redness, swelling, heat and pain, and in mild cases it can subside on its own or break down in three to five days when the abscess matures. The chalazion, on the other hand, is a painless mass that takes a long time to develop and the color of the redness is not so bright red, but dark red and purplish red. This is not difficult to distinguish, right? What if the distinction is complete? It should be treated actively. For the treatment of wheals, it is usually antibiotic treatment. If the lump does not subside, it is necessary to perform a surgical incision to drain the pus. The principle of treatment for chalazion is to adhere to hot compress treatment, antibiotic treatment is ineffective, if necessary, can be surgically scraped, so that it can be resolved.