The causes of left eye congestion are complex and can be caused by trauma, dry eye, conjunctivitis, etc. You should seek medical advice to find out the cause of the problem. 1. In daily life, due to the violent impact on the left eye, resulting in the rupture of tiny blood vessels in the eye, the symptom of congestion in the left eye can occur. 2. Dry eye syndrome is mostly caused by eye diseases or surrounding environmental factors, resulting in decreased tear film stability, combined with eye discomfort and conjunctival lesions, which can lead to symptoms of left eye congestion. 3. Conjunctivitis is mostly caused by pathogenic microorganisms, external stimuli or allergic reactions, resulting in conjunctival vasodilatation combined with inflammatory infiltration, which can lead to symptoms of left eye congestion. If the symptoms of left eye congestion exist for a long time, you should be vigilant and seek medical attention to identify the cause of the disease and follow the doctor’s instructions for treatment.