What causes congestion in the left eye fundus?

Left eye redness may be caused by various factors, including but not limited to eye fatigue, foreign bodies in the eye, trauma, dry eye syndrome, and conjunctivitis. Eye fatigue may result from prolonged熬夜 (staying up late) or extended use of electronic devices. Foreign bodies in the eye may repeatedly abrade and irritate ocular tissues. Trauma can lead to rupture of capillaries in the left eye. Dry eye syndrome and conjunctivitis may trigger ocular blood vessel congestion due to inflammatory mediators stimulating the eye.