A child’s vision of 0.25 is particularly serious, as it is usually between 0.8 and 0.9. And the cause of 0.25 vision in children may be due to refractive errors, congenital cataracts and so on. It is recommended to go to the ophthalmology department for visual acuity examination first, and then diagnose according to the condition of cornea and fundus examination. 1. Refractive error: caused by organic or functional changes in the refractive system of the eye, the image will not be accurately focused on the retina to produce a clear image. It manifests itself as myopia, hyperopia, astigmatism and other symptoms. It is mainly caused by children’s prolonged incorrect reading habits, incorrect application of night-light, and fewer outdoor activities. It is recommended to use corneal contact lenses or surgical treatment to focus the light on the retina, thus improving and correcting the vision. 2. Congenital cataract: It is caused by family genetic history and maternal factors, so that the fetus is affected by various factors at the time of lens development, which makes the lens protein synthesis abnormal, thus leading to the occurrence of the disease. And manifested as vision loss, blurred vision, amblyopia and so on. Parents are advised to bring their children to the doctor in time to avoid delay in diagnosis and treatment.