Conjunctival congestion can be divided into simple conjunctival congestion, ciliary congestion and mixed congestion depending on the location, and different causes depending on the accompanying other ocular symptoms. If the conjunctival congestion becomes more pronounced near the fornix and is bright red, it is usually simple conjunctival congestion, while if it is near the black eye and is dark red, it is usually ciliary congestion. There are many causes of eye congestion, including fatigue, alcohol, constipation, excessive eye use, and hot water bathing, which can cause vasodilation, and this category often manifests as bilateral congestion without significant discomfort in the other eyes. If conjunctival congestion is accompanied by obvious foreign body sensation and tingling, consider whether it is caused by eyelid impingement, eyelid stones, foreign bodies in the conjunctival sac or corneal foreign bodies, and promptly remove the cause and perform anti-inflammatory treatment; if conjunctival congestion is accompanied by eye grinding and photophobia and eye discharge, consider it to be caused by conjunctivitis, and perform anti-inflammatory treatment according to the cause; if conjunctival congestion is accompanied by obvious vision loss in addition to eye redness and eye pain and foreign body sensation, it may be caused by keratitis, keratoconjunctivitis, or other eye discomfort. If conjunctival congestion is accompanied by ocular swelling and pain, headache or nausea and vomiting, it is considered to be caused by acute attack of closed-angle glaucoma, which should be treated by anti-inflammatory therapy and IOP lowering in a timely manner. Therefore, conjunctival congestion can be classified into different causes depending on the location and the accompanying other ocular symptoms, such as inflammation in different areas, foreign bodies or glaucoma, and should be promptly seen in the hospital for a clear diagnosis and causal treatment.