We usually talk about eye congestion, which is often called “eye redness”, and on examination, the main things that can be seen are conjunctival congestion, ciliary congestion and mixed congestion. Conjunctival congestion is characterized by a more pronounced congestion the farther away from the edge of the cornea (the black eye), suggesting that the lesion involves the surface of the eye. It can be caused by many factors, including infection, local irritation, allergies, and topical medications. Ocular infections, including bacterial, viral, or parasitic infections, can cause ocular congestion and can be treated with topical antibiotics and antiviral medications. Local irritants include smoke, haze, strong winds, chemical volatiles, ultraviolet radiation, etc. The obvious feature is that the congestion of the eyes improves with the removal of these external irritants. Eye congestion may also be due to the patient’s own allergic constitution, triggered by contact with irritating environments or eating foods that induce allergies whenever they are used, and antiallergic medications are mostly irritating when used for long periods of time. Ciliary congestion, characterized by just the opposite of the previously mentioned conjunctival congestion, only the blood vessels at the corneal limbus are congested, while the congestion in areas away from the corneal limbus is lessened or insignificant. This kind of manifestation suggests that there may be inflammation inside the eyeball, such as iridocyclitis or glaucoma, or even endophthalmitis. We should improve the examination to determine the cause of the disease, and if it is iridocyclitis, we should give hormone-type ophthalmic solution. If the patient has glaucoma, we suggest that we should lower the intraocular pressure, and treat the symptoms, and then consider whether to have surgical treatment or laser treatment after the control and stabilization of the intraocular pressure. Mixed congestion, refers to the simultaneous occurrence of the above two conditions, manifested as diffuse congestion of the bulbar conjunctiva, suggesting that the ocular lesions are aggravated, and it is necessary to go to the hospital in time for consultation. In addition, a foreign body in the eye, eye trauma, or eye fatigue, long-term stay up all night, may appear eye congestion. To sum up, you should arrive at the hospital in time to be diagnosed by a specialized doctor through professional examination.