Blindness in the context of "Joint attention"

Braille (/ˈbreɪl/ BRAYL, French: [bʁaj] ) is a tactile writing system used by blind or visually impaired people. It can be read either on embossed paper or by using refreshable braille displays that connect to computers and smartphone devices. Braille can be written using a slate and stylus, a braille writer, an electronic braille notetaker or with the use of a computer connected to a braille embosser. For blind readers, braille is an independent writing system, rather than a code of printed orthography.

Braille is named after its creator, Louis Braille, a Frenchman who lost his sight as a result of a childhood accident. In 1824, at the age of fifteen, he developed the braille code based on the French alphabet as an improvement on night writing. He published his system, which subsequently included musical notation, in 1829. The second revision, published in 1837, was the first binary form of writing developed in the modern era.

Trachoma is an infectious disease caused by bacterium Chlamydia trachomatis. The infection causes a roughening of the inner surface of the eyelids. This roughening can lead to pain in the eyes, breakdown of the outer surface or cornea of the eyes, and eventual blindness. Untreated, repeated trachoma infections can result in a form of permanent blindness when the eyelids turn inward.

The bacteria that cause the disease can be spread by both direct and indirect contact with an affected person's eyes or nose. Indirect contact includes through clothing or flies that have come into contact with an affected person's eyes or nose. Children spread the disease more often than adults. Poor sanitation, crowded living conditions, and insufficient clean water and toilets also increase spread.

The slate and stylus are tools used by blind people to write text that they can read without assistance. Invented by Charles Barbier as the tool for writing letters that could be read by touch, the slate and stylus allow for a quick, easy, convenient and constant method of making embossed printing for Braille character encoding. Prior methods of making raised printing for the blind required a movable type printing press.

The visual system is the physiological basis of visual perception (the ability to detect and process light). The system detects, transduces and interprets information concerning light within the visible range to construct an image and build a mental model of the surrounding environment. The visual system is associated with the eye and functionally divided into the optical system (including cornea and lens) and the neural system (including the retina and visual cortex).

The visual system performs a number of complex tasks based on the image forming functionality of the eye, including the formation of monocular images, the neural mechanisms underlying stereopsis and assessment of distances to (depth perception) and between objects, motion perception, pattern recognition, accurate motor coordination under visual guidance, and colour vision. Together, these facilitate higher order tasks, such as object identification. The neuropsychological side of visual information processing is known as visual perception, an abnormality of which is called visual impairment, and a complete absence of which is called blindness. The visual system also has several non-image forming visual functions, independent of visual perception, including the pupillary light reflex and circadian photoentrainment.

A screen reader is a form of assistive technology (AT) that renders text and image content as speech or braille output. Screen readers are essential to blind people, and are also useful to people who are visually impaired, illiterate or learning-disabled. Screen readers are software applications that attempt to convey what people with normal eyesight see on a display to their users via non-visual means, like text-to-speech, sound icons, or a braille device. They do this by applying a wide variety of techniques that include, for example, interacting with dedicated accessibility APIs, using various operating system features (like inter-process communication and querying user interface properties), and employing hooking techniques.

Microsoft Windows operating systems have included the Microsoft Narrator screen reader since Windows 2000, though separate products such as Freedom Scientific's commercially available JAWS screen reader and ZoomText screen magnifier and the free and open source screen reader NVDA by NV Access are more popular for that operating system. Apple Inc.'s macOS, iOS, and tvOS include VoiceOver as a built-in screen reader, while Google's Android provides the Talkback screen reader and its ChromeOS can use ChromeVox. Similarly, Android-based devices from Amazon provide the VoiceView screen reader. There are also free and open source screen readers for Linux and Unix-like systems, such as Speakup and Orca.

Nikola Altomanović (Serbian Cyrillic: Никола Алтомановић; died after 1395) was a 14th-century Serbian župan of the House of Vojinović. He ruled the areas from Rudnik, over Polimlje, Podrinje, east Herzegovina with Trebinje, reaching as far as Konavle and Dračevica, neighboring the Republic of Dubrovnik. He was defeated and blinded in Užice (fortress Užice) in 1373 by a coalition of his Serbian and Bosnian royals neighbors supported by the king of Hungary.