By the 10th Revision of the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, low vision is defined as visual acuity of less than 20 / 60 ( 6 / 18 ), but equal to or better than 20 / 200 ( 6 / 60 ), or corresponding visual field loss to less than 20 degrees, in the better eye with best possible correction.

By the end of the 10th century, the Norse minority had merged with the Slavic population, which also absorbed Greek Christian influences in the course of the multiple campaigns to loot Tsargrad, or Constantinople.

By the turn from the 10th to the 11th century, the smaller burghs in the Parseta area were given up.

By the end of the 10th century, Aragon was annexed by Navarre.

By size, it is the 8th largest state in Germany, and by population, the 10th largest.

Another possible predecessor state was called Po-ni ( pinyin: Boni ) By the 10th century Po-ni had contacts with first the Song dynasty and at some point even entered into a tributary relationship with China.

By the late 9th and early 10th centuries, Bulgaria extended to Epirus and Thessaly in the south, Bosnia in the west and controlled all of present-day Romania and eastern Hungary to the north.

By the 10th century Reims had become a centre of intellectual culture.

By the 10th century the table fork was in common use throughout what is now the Middle East and Turkey.

By the 10th century BCE a rudimentary state had emerged in the north-central highlands, and in the 9th century this became a kingdom.

By the 10th century AD, cultivation had begun in East Africa.

By the late 10th century the tradition of skaldic verse had increasingly moved to Iceland and Norwegian rulers such as Eiríkr Hákonarson and St. Olaf employed mostly Icelandic poets.

By the 10th century, many of Paris's parish cemeteries were well within city limits, and eventually some, because of their central location in dense urban growth, were unable to expand and became overcrowded.

By the time the official order to take Nanking arrived from Imperial Headquarters on December 1, both the 10th Army and the Shanghai Expeditionary Force had been marching westward for almost 3 weeks.

By 1913, Argentina was the world's 10th wealthiest nation per capita.

By the 10th century, Germanic paganism had become restricted to Scandinavia.

By 1844 Jefferson was providing patient beds over a shop at 10th and Sansom Streets.

By 10th century, the myth of Afrasiyab was adopted by the Qarakhanid dynasty.

By the 10th century such Anglo-Norse crosses were the bulk of the production in England, as the high cross seems to have been abandoned further south, although the simple and practical Dartmoor crosses, no doubt an essential aid to navigating Dartmoor, appear to have continued to be made for centuries after.

By the middle of the 10th century, fee had largely become hereditary.

By the 10th century, a chapel and market place were already established.

By the 10th century, domed tombs had been built for Abbasid caliphs and Shiite martyrs.

By the 10th century, the canons started the construction of the church of Saint Vincent ( Madelgaire ), which was to be completed during the following century in the prevalent Romanesque style of the period.

By the 10th century catacombs were practically abandoned, and holy relics were transferred to above-ground basilicas.

By early December 2001 troops from the 10th Mountain Division shared the base with Special Operations Command officers from MacDill Air Force Base in Florida and soldiers of the 82nd Airborne Division from Fort Bragg.

By the end of the nineteenth century, in 1893, when the Big Three, Columbia, and Penn were populous centers of learning, Dartmouth graduated only sixty-nine.

By the end of the century the Roman Catholic Church was beginning to make itself felt, mainly through such institutions as hospitals but also through its attitude towards organized labour.

By the 27th century BC Egyptian writing had a set of some 24 hieroglyphs which are called uniliterals, to represent syllables that begin with a single consonant of their language, plus a vowel ( or no vowel ) to be supplied by the native speaker.

By the tenth century two other forms can be distinguished namely Canaanite and Aramaic.

By the end of the 14th century, most of Anatolia was controlled by various Anatolian beyliks.

By the 6th century BC, the Celtic La Tène culture was well established.

By the mid-19th century scientists began to arrive en masse to study the geology and ecology of the region.

By the late 5th century BC, philosophers might separate Aphrodite into two separate goddesses, not individuated in cult: Aphrodite Ourania, born from the sea foam after Cronus castrated Uranus, and Aphrodite Pandemos, the common Aphrodite " of all the folk ," born from Zeus and Dione.

By the beginning of the 8th century, these kingdoms had either been conquered by Nicene neighbors ( Ostrogoths, Vandals, Burgundians ) or their rulers had accepted Nicene Christianity ( Visigoths, Lombards ).

By the middle of the 19th century, industrialisation swept away most of the city's medieval rules of production and commerce, although the entirely corrupt remains of the city's mediæval constitution was kept in place ( compare the famous remarks of Georg Forster in his Ansichten vom Niederrhein ) until 1801, when Aachen became the " chef-lieu du département de la Roer " in Napoléon's First French Empire.

By the 6th century Alexander's commentaries on Aristotle were considered so useful that he was referred to as " the commentator " ().

By the mid-4th century however the assembly's judicial functions were largely curtailed, though it always kept a role in the initiation of various kinds of political trial.

By the mid-16th century, they were in common use in most of Europe.

By the standards of 19th century tycoons, Carnegie was not a particularly ruthless man but a humanitarian with enough acquisitiveness to go in the ruthless pursuit of money ; on the other hand, the contrast between his life and the lives of many of his own workers and of the poor, in general, was stark.

By the 7th century BC, much of the Assyrian population used Akkadian influenced Eastern Aramaic and not Akkadian itself.

By the 4th century AD artists had started debating in writing over the proper goals of art as well.

By the end of the twentieth century " Negro " had come to be considered inappropriate and was rarely used and perceived as a pejorative.

By the early 5th century Britain had been Roman for over three hundred and fifty years.

By the 1st century BC, Aediles were elected in July, and took office on the first day in January.

By the 16th century, a cappella polyphony had further developed, but gradually, the cantata began to take the place of a cappella forms.

By the 19th century orchestral music in Europe had standardized the string section into the following homogeneous instrumental groups: first violins, second violins, violas, cellos, and double basses.

By the 3rd century BC, the rival armies of Carthage and Rome began to invade and fight for control of the Iberian Peninsula.

By the 5th century AD, Rome was in decline and the Roman predecessor town of Alicante, known as Lucentum ( Latin ), was more or less under the control of the Visigothic warlord Theudimer.

By the end of the 18th century there were no factories or mills and only a few small cottage industries along the border with Zurich.

By the beginning of the twentieth century, Steiner's interests turned to explicitly spiritual areas of research.