The Tibetan eye chart is a tool allegedly developed by Tibetan monks.[1][unreliable source?][2][unreliable source?][3][unreliable source?] According to some authors, it can be used to train the muscles and nerves of the optical system, correcting visual problems.[4][unreliable source?][5][unreliable source?] However, the International Orthoptic Association has found no scientific evidence of the effectiveness of this treatment.[6][verification needed]