It is true that prism is used to treat nystagmus in clinic. Prism has two functions: improving vision and eliminating abnormal head position, thus achieving the effect of treating nystagmus. The principle of treatment is that congenital nystagmus can be alleviated or suppressed in static eye position and in dark environment by convergence. But it may not work. In addition, Chinese medicine uses acupuncture and western medicine uses surgery. The effect is not absolutely certain. It is estimated that the eyes have amblyopia.