Sudden ocular congestion is clinically manifested by the presence of congestion in the conjunctiva. There are many causes of congestion, including visual fatigue, conjunctivitis, keratitis, glaucoma, uveitis, or foreign bodies in the conjunctival sac, corneal foreign bodies, impingement, conjunctival stones, etc. Since the conjunctiva communicates with the outside world, a variety of microorganisms such as bacteria, viruses, fungi, etc., or foreign bodies, or dust irritation, ultraviolet light, etc. can cause conjunctival pathology. Therefore, if you find significant congestion in the eyes, you should first identify the cause of the problem in order to treat it properly. If the conjunctiva is congested and there is a significant increase in discharge from the corner of the eye or the conjunctival sac, consider conjunctivitis caused by infection. If the congestion is accompanied by photophobia, tearing, stinging, or even blurred vision, it may be keratitis, uveitis, etc. If the eyes are congested with blood and accompanied by symptoms such as swelling and soreness of the eyes, it may be glaucoma. If the eye is congested and there is a significant foreign body sensation, it may be caused by a foreign body in the conjunctival sac, a foreign body in the cornea, or irritation of the inverted eyelashes, etc. Therefore, if you notice significant congestion in the eyes, it is recommended to visit the ophthalmology department of your local hospital.