Louis Émile Javal of text, but make short rapid movements (saccades) intermingled with short stops (fixations). Javal's observations were characterised by a reliance on naked-eye observation of eye movement in the absence of technology. Javal's interest in strabismus was due to the disorder affecting his father and sister. Javal himself had heterochromia. At middle-age Javal developed glaucoma, and by 1900 was totally blind. He was a friend of Ludwik Łazarz Zamenhof (1859-1917), the inventor of Esperanto, and he stressed the importance of learning this language by the blind. In addition, he was involved in social reform issues that included education and circumstances surrounding
L. L. Zamenhof international language must have a simpler grammar. Apart from his parents' native languages Russian and Yiddish and his adopted language Polish, his linguistics attempts were also aided by his mastering of German, a good passive understanding of Latin, Hebrew and French, and a basic knowledge of Greek, English and Italian. By 1878, his project "Lingwe uniwersala" was almost finished. However, Zamenhof was too young then to publish his work. Soon after graduation from school he began to study medicine, first in Moscow, and later in Warsaw. In 1885, Zamenhof graduated from a university and began his practice as a doctor