The human eye is made up of 3 layers of wall and contents, the uvea is the middle layer of the wall, which is immediately adjacent to the inner side of the white eye. The reason for the eye’s visual function is closely related to the uvea. The uvea is rich in blood vessels and pigments that provide the eye with blood flow and nutrients, and because it contains a large amount of pigments, it acts as a dark box similar to that of a camera, allowing light to gather in the eye instead of scattering freely, creating clear and sharp vision. What is uveitis? The uvea is divided into three parts: the iris, the ciliary body and the choroid, and inflammation of any of these parts is called uveitis. However, all types of inflammation in the eye basically involve these three parts, so sometimes uveitis refers to inflammation in the eye in general. In addition, because the uvea is rich in blood flow, disease-causing substances from the blood can easily be trapped and deposited there, so uveitis is often closely related to systemic diseases. What are the symptoms of uveitis? Patients with uveitis typically have red eyes, eye pain, photophobia and blurred vision. However, these symptoms can also occur with other types of eye disease, such as conjunctivitis and glaucoma. Therefore, if these symptoms occur, you must go to a professional medical institution for an examination to determine if it is uveitis, and you should never self-diagnose and use private medication. How can I simply distinguish between uveitis and other eye diseases from the symptoms? Eye pain in patients with uveitis is a grinding pain that is not very intense, while eye pain due to glaucoma is often distending, and patients often feel swelling throughout the eye or even half a headache. In the case of pain caused by conjunctivitis, it is usually sporadic, while pain due to uveitis is constant. In addition, patients with uveitis who experience vision loss usually experience a sudden drop. The patient may be fine one day and suddenly have a black shadow in front of his or her eyes two days later, and the condition is very acute. Vision loss due to other types of eye disease, such as cataracts, is usually gradual and worsens over months or years.