Eye redness is caused by the expansion of blood vessels in the conjunctiva and congestion, and a variety of eye diseases can lead to eye redness. The eye fatigue is related to long hours of eye use and staying up late. It can be treated by using artificial tears, such as sodium carboxymethylcellulose drops. 4. caused by allergic conjunctivitis, it can be treated with histamine receptor antagonist drops, such as nalmivir drops.