Various diseases of the eyes cause the following three main symptoms: First, visual impairment: that is, blurred vision. Visual impairment can be a sudden or gradual loss of vision, accompanied by eye pain, which can be described as not seeing clearly at a distance, not seeing clearly near, seeing things sometimes distorted and smaller, having night blindness, diplopia, visual field defects, and having fixed or floating black shadows in front of the eyes, etc. This is a common symptom. Second, abnormal sensation: the eye appears tingling, swelling, itching, foreign body sensation, photophobia, etc. Sometimes there is also redness, congestion and tearing of the eyes, these symptoms are called abnormal sensation. Third, abnormal appearance: the appearance can be seen in the eyes with secretions, swollen eyes, new organisms, cysts, or abnormal eyelid position, protrusion of the eyeball, etc. So no matter which disease of the eye, it will mainly be manifested in three aspects: visual impairment, sensory abnormalities and abnormal appearance.