A vision of 0.5 is definitely abnormal, as normal vision is usually around 1.0. If the vision is only 0.5 in one or both eyes, there may be refractive or fundus cataract problems. Especially in children, if the vision is only 0.5, there may be myopia or high number of farsightedness or astigmatism, which requires active dilated eye examinations. If there is a refractive problem, glasses are needed for correction, and they need to be worn all the time. If an adult has 0.5 vision, most of them can improve their vision by wearing myopic glasses due to myopia. Of course older adults may also have vision loss due to cataracts or macular degeneration of the fundus. Usually cataracts require surgery to resolve, and macular degeneration requires appropriate treatment depending on the nature and extent of the lesion.