Causes of night blindness include genetic diseases such as retinitis pigmentosa; acquired diseases such as diabetic retinopathy, posterior uveitis, glaucoma, high myopia, and systemic diseases such as vitamin A deficiency. In addition, drug factors and environmental factors can also affect night blindness. 1. Hereditary diseases: Retinitis pigmentosa, which is usually caused by other hereditary retinal diseases, starts in childhood or early adolescence, and the symptoms of night blindness are progressively aggravated, mainly including primary retinitis pigmentosa, but also can be seen in microphthalmos and crystalline retinitis. 2. Acquired factors: (1) Acquired eye diseases: night blindness caused by retinal rod cell damage secondary to acquired eye diseases, common eye diseases include retinal choroiditis, hemorrhagic retinitis, diabetic retinopathy, iron or copper deposition, glaucoma, high myopia, and so on. (2) Systemic diseases: Vitamin A deficiency caused by liver disease, malnutrition, gastrointestinal disease, and retinopathy caused by diabetes, etc., which can also impair the function of the optic rod cells or impaired synthesis of the optic pigment, thus causing night blindness. 3. Drug factors: pupil-shrinking medicines hairy fruit Yunxiang alkaloids in the use, will cause dark vision impairment, especially the elderly and patients with lens clouding, nuclear cataract patients more obvious. 4. Environmental factors: long-term exposure of the eyes to bright light will seriously impair vision, and sometimes lead to dark place vision impairment, resulting in the occurrence of night blindness. The causes of night blindness are complex, and it is important to consult a doctor in time to identify the cause of the disease and carry out targeted treatment under the guidance of the doctor.