Dry eye is a type of disease in which the tear film is unstable and the eye surface is damaged due to abnormalities in the quantity or quality of tears, resulting in ocular discomfort. It is the most common ocular surface disease. Dry eye is a continuous pathological process that progresses from mild to severe, and there is no clear line of demarcation between mild and moderate severity. In general, any symptom or combination of signs should be diagnosed as a pathological condition, for example, the diagnostic criteria for dry eye in some regions of the United States is as long as the patient presents with symptoms of dry eye (with or without signs). Clinical manifestations Symptoms and medical history The common symptoms of dry eye are: dryness, foreign body sensation, burning sensation, itching, photophobia, eye redness, blurred vision, and fluctuating visual acuity. In addition, a survey found that 71.3% of dry eye patients had symptoms of visual fatigue, indicating that visual fatigue is also a common symptom of dry eye. The positive rate of objective examination is significantly lower than the incidence of dry eye symptoms such as only 2.2% of the above survey in the United States had both symptoms and low ST (Schirmer’s test) (≤5mm/5min), and 2.0% had both symptoms and high ocular surface tiger red staining score (≥5). Therefore, in order to reduce the underdiagnosis of dry eye, we should pay attention to the inquiry of symptoms. For more severe dry eye, asking whether there is dry mouth and joint pain can suggest the possibility of SS. Asking about past systemic and local medications, surgical history and working environment can be of great help in the diagnosis of dry eye. Treatment Treating the cause is the best way to treat any disease. In the treatment of dry eye, discovering the cause of dry eye and treating the cause is undoubtedly the key to dry eye treatment, such as systemic diseases, and treating the primary cause together with the appropriate specialist. The occurrence and exacerbation of some dry eyes are related to the living and working environment, such as working in an air-conditioned environment for a long time, using computers frequently or driving at night. Therefore, long-term systemic application of certain medications such as sedatives, antispasmodics, and decongestants can also cause dry eye and should be discontinued promptly. If the dry eye is caused by eye cosmetics, stop using cosmetics near the lid margin and swab the lid margin with a cotton swab to remove the cosmetics and lid gland oil. In addition, smoking, swimming, and long-term use of various eye medications can also cause dry eye and should be taken into account. However, because of the complexity of the causes of dry eye, it is often difficult for many patients to identify the cause. For patients with systemic diseases, systemic treatment is often ineffective, and for these dry eye patients, relief of dry eye symptoms is an important goal of treatment.