Glossary

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Remote Sighted Assistance(also: Remote Visual Assistance, Visual Interpreting, Remote Sighted Guide)

A service model in which a sighted person provides real-time visual information to a blind or visually impaired person remotely, typically through a smartphone video call. The blind user points their phone camera at what they need help with, and the sighted helper describes what…

Remote sighted assistance(also: RSA, Visual interpreting service)

A service connecting blind or visually impaired individuals with sighted helpers through live video calls, enabling real-time visual guidance for everyday tasks. Services like Be My Eyes (volunteer-based), Aira (professional agents), and similar platforms allow BVI users to…

Residual vision(also: Functional vision, Usable vision)

The remaining visual ability of a person with a visual impairment, which may include partial acuity, limited visual field, or light perception. The vast majority of people classified as legally blind have some residual vision rather than total blindness. Assistive technology and…

Restricted Field of View(also: Tunnel Vision, Peripheral Vision Loss, Visual Field Loss)

A condition in which the area of the visual environment that a person can see at any given moment is significantly reduced, often described as looking through a tunnel or a narrow tube. Restricted field of view can result from conditions such as glaucoma, retinitis pigmentosa,…

Retinitis Pigmentosa(also: RP)

A group of inherited genetic disorders that cause progressive degeneration of the retina, typically beginning with loss of night vision and peripheral vision and potentially leading to tunnel vision or complete blindness. RP affects the rod photoreceptor cells first, then may…

Retinitis Pigmentosa(also: RP, Retina Pigmentosa, Rod-Cone Dystrophy)

A group of inherited genetic disorders that cause progressive degeneration of the retina, leading to gradual vision loss. Initial symptoms typically include difficulty seeing in low light (night blindness) and loss of peripheral vision (tunnel vision). The condition often begins…

Retinitis pigmentosa(also: RP)

A group of inherited genetic disorders that cause progressive degeneration of the retina, typically beginning with loss of night vision and peripheral vision and gradually narrowing the visual field (tunnel vision) over years or decades. Some people with RP eventually lose most…

Retinopathy(also: Diabetic Retinopathy, Retinal Disease)

A group of eye conditions affecting the retina that can cause vision loss or blindness. Diabetic retinopathy, caused by damage to blood vessels in the retina due to diabetes, is one of the leading causes of blindness in working-age adults. Symptoms may include blurred vision,…

Retinopathy of Prematurity(also: ROP)

An eye condition that can occur in premature infants when abnormal blood vessels grow in the retina. In severe cases, these vessels can cause scarring, retinal detachment, and significant vision loss or blindness. ROP is one of the leading causes of childhood blindness and low…

Scene simplification(also: Visual decluttering, Complexity reduction)

An assistive technology approach that reduces visual complexity in real-world or digital scenes by highlighting relevant objects, suppressing background clutter, and isolating key information. Scene simplification is particularly important for people with cerebral visual…

Scotoma(also: Blind Spot, Visual Field Defect)

An area of partial or complete loss of vision within an otherwise normal visual field. Scotomas can be central (affecting the area of sharpest vision) or peripheral, and may be caused by conditions such as macular degeneration, glaucoma, optic neuritis, or retinal damage. In the…

Screen magnifier(also: Screen magnification software, Zoom software)

Assistive software that enlarges a portion of the screen display to make content visible for people with low vision. Users navigate the magnified view by panning with the mouse or keyboard, seeing only a fraction of the full screen at any time. Popular screen magnifiers include…

Semantic Bookmarking(also: Semantic Bookmark, Concept-Based Bookmarking)

A web navigation technique that associates saved page locations with meaningful conceptual labels from a domain ontology rather than with specific structural positions in the HTML code. Unlike traditional bookmarks that reference a URL or a position in the document's DOM tree…

Sighted Assistance(also: Visual Interpreting, Remote Sighted Assistance)

Sighted assistance refers to services that connect blind or low-vision individuals with sighted people who can provide visual information on demand, typically through a live video call from a smartphone or smart glasses. Services like Be My Eyes (volunteer-based) and Aira…

Sighted Braille Learner(also: Visual Braille Learner)

A person with typical vision who learns to read and write braille, usually for professional or personal reasons such as teaching blind students or supporting a blind family member. Sighted braille learners process braille visually rather than tactilely, which creates a…

Simultanagnosia(also: Simultagnosia)

A neurological condition in which a person can perceive individual objects but cannot see or process multiple objects simultaneously within a visual scene. Simultanagnosia is a common feature of cerebral visual impairment and dorsal stream dysfunction. In everyday life, it makes…

Smart Glasses(also: AR Glasses, Assistive Smart Glasses)

Smart glasses are head-mounted wearable devices that incorporate cameras, microphones, speakers, and computing capabilities into an eyeglass form factor. For people who are blind or have low vision, smart glasses can use computer vision and AI to provide real-time information…

Spatial Awareness(also: Spatial Cognition, Environmental Awareness)

The understanding of one's surrounding environment and one's own position within it. In accessibility contexts, spatial awareness encompasses multiple dimensions: the scale and shape of an area, one's position and orientation within it, the presence and arrangement of objects,…

Spatial Orientation and Navigation(also: SON, Orientation and Navigation)

The set of skills and strategies used to understand one's position in space, plan routes, and travel from one location to another. For blind and low-vision individuals, spatial orientation and navigation involves using non-visual cues — sound, touch, proprioception,…

Split Tap(also: Split Tapping)

A touchscreen interaction technique where the user holds one finger on a target element while tapping with a second finger to activate it. Split tap allows blind users to explore the screen with one finger to locate elements (hearing each one announced) and then tap elsewhere to…

Stargardt Disease(also: Stargardt Macular Dystrophy, Fundus Flavimaculatus)

An inherited eye condition that causes progressive vision loss affecting the macula, the central part of the retina responsible for sharp, detailed vision. Stargardt disease typically begins in childhood or adolescence and leads to reduced central visual acuity while peripheral…

Strabismus(also: Crossed eyes, Squint, Eye misalignment)

A condition in which the eyes do not align properly, causing one eye to point in a different direction from the other — inward (esotropia), outward (exotropia or exophoria), upward, or downward. Strabismus disrupts binocular coordination and can lead to double vision, amblyopia,…

Swell Paper(also: Capsule Paper, Microcapsule Paper, PIAF Paper)

A special paper coated with heat-sensitive microcapsules that swell when exposed to heat, creating raised tactile surfaces from printed black areas. When passed through a heating device (such as a PIAF — Pictures In A Flash — machine), dark-printed lines and shapes become raised…

Table Reading Style(also: Table Reading Strategy, Table Browsing Style)

The particular way in which a reader accesses and processes the content of a data table, determined by the interaction between the table's structure, content, and the reader's intent. Common table reading styles include: by cell (random access to individual cells), by row…

Tactile Graphic(also: Tactile Image, Raised-Line Graphic, Tactile Diagram)

A physical representation of visual information that uses raised lines, textures, and relief to convey images, diagrams, maps, and other visual content through touch. Tactile graphics are essential for blind and visually impaired people to access visual information in education,…

Tactile Graphic Reader(also: Tactile Graphic Display, Tactile Image Reader)

A device that combines physical tactile graphics (raised-line images on paper) with digital audio feedback, enabling blind and visually impaired users to explore graphical content through touch while receiving spoken or sonified information about the elements they contact.…

Tactile Graphicacy(also: Tactile Literacy, Tactile Reading Skills)

The learned ability to read, interpret, and create meaning from tactile images, maps, diagrams, and graphics through touch. Just as visual graphicacy is developed through exposure to visual images, tactile graphicacy requires practice with a wide range of tactile materials and…

Tactile Reading(also: Touch Reading)

The process of reading text through the sense of touch, primarily using the fingertips to perceive raised characters such as braille. Tactile reading requires distinct perceptual and cognitive skills from visual reading, including fine tactile discrimination, spatial pattern…

Tactile graphic production(also: Tactile image creation, Accessible graphic transcription)

The process of converting visual images — such as textbook diagrams, charts, maps, and illustrations — into raised tactile representations that can be explored by touch. Production methods include swell paper (microcapsule paper heated to raise printed lines), embossing,…

Tap-to-Hear(also: Point-to-Hear, Tap-to-Listen, Point-and-Click Exploration)

An interaction paradigm used in tactile graphic readers and touch-based accessibility tools where users touch or tap on elements of a tactile graphic to trigger spoken audio descriptions of the element beneath their finger. Tap-to-hear is the current standard approach for…

Teacher of Students with Visual Impairments(also: TVI, Vision Teacher, Teacher of the Visually Impaired)

A specialized educator certified to teach students who are blind or have low vision, providing instruction in the expanded core curriculum including braille literacy, orientation and mobility concepts, assistive technology use, and daily living skills. TVIs work in school…

Thermoform(also: Vacuum-Formed Plastic, Thermoform Duplicator)

A method of producing tactile images and braille copies by heating a thin sheet of plastic and vacuum-forming it over a master copy (typically an embossed original) to create a durable raised-line reproduction. Thermoform machines heat plastic sheets and use vacuum pressure to…

Touch Exploration(also: Explore by Touch, Touch-Based Exploration)

An interaction method that allows users to discover on-screen content by moving their finger across a touchscreen, receiving audio feedback about elements under the fingertip. Touch exploration is fundamental to how blind and low-vision users navigate mobile devices through…

Touchscreen text entry(also: Mobile typing, Virtual keyboard input)

The process of entering text on a touchscreen device using a virtual keyboard, which presents significant accessibility challenges for blind and visually impaired users who cannot see key boundaries or visual feedback. Screen reader users typically employ an explore-then-lift…

Trajectory Playback(also: Haptic Playback, Force-Guided Movement)

A technique in haptic interfaces where a force-feedback device physically guides a user's hand through a predefined path or shape. The system applies forces to move the user along a trajectory, allowing them to perceive spatial information through proprioception and kinesthetic…

Tunnel Vision(also: Peripheral Vision Loss, PVL)

A visual impairment characterized by the loss of peripheral vision while central vision may remain intact, resulting in a narrow field of view as if looking through a tunnel. Tunnel vision can be caused by conditions such as retinitis pigmentosa, glaucoma, or stroke. It…

Typhlology(also: Typhlopedagogy)

The study and science of blindness and visual impairment, encompassing education, rehabilitation, and support methods for people who are blind or have low vision. Typhlology draws on knowledge from education, psychology, medicine, and assistive technology to develop teaching…

Unified English Braille(also: UEB)

The standard braille code used for English-language literary materials in the United States, United Kingdom, Australia, Canada, and other English-speaking countries. UEB was adopted to replace multiple competing braille codes with a single unified system, providing consistent…

Video accessibility(also: Accessible video, Video a11y)

The practice of making video content perceivable, operable, and understandable for people with disabilities. This encompasses captions for deaf and hard-of-hearing viewers, audio descriptions for blind users, visual enhancements for low-vision users, and controls that work with…

Virtual World Accessibility(also: Metaverse Accessibility, VR Accessibility for Blind Users)

Virtual world accessibility refers to the design and implementation of techniques that enable people with disabilities, particularly blind and visually impaired users, to participate in 3D virtual environments such as online virtual worlds, VR platforms, and metaverse…

Visual Acuity(also: VA, Sharpness of Vision)

A measure of the eye's ability to distinguish fine details and shapes at a given distance. Visual acuity is commonly expressed as a Snellen fraction (e.g., 20/20, 20/200) or in logMAR units used in clinical research. It is the primary metric for classifying levels of vision…

Visual Hallucination(also: AI hallucination, MLLM hallucination)

In the context of multimodal AI systems, visual hallucination refers to the generation of descriptions or responses that contain information not grounded in the actual visual input—fabricating non-existent objects, misattributing properties such as colour or size, or…

Visual Impairment(also: Vision Impairment, Low Vision, Sight Loss)

A reduction in the ability to see that cannot be fully corrected with standard glasses, contact lenses, or medical treatment. Visual impairments range from low vision (partial sight) to total blindness and include conditions like macular degeneration, glaucoma, diabetic…

Visual Interpretation Service(also: VIS, Visual Assistance Service, Remote Sighted Assistance)

A service that provides visual information to blind and low vision users through human assistants, AI-powered tools, or a combination of both. Traditional visual interpretation services like Aira connect users via video call to trained human agents who describe visual…

Visual Privacy(also: Visual Information Privacy)

The safeguarding and management of sensitive visual information that could be shared or disclosed in everyday life, particularly through the use of assistive technologies and generative AI tools. For blind and low vision users, visual privacy encompasses multiple dimensions:…

Visual Profile(also: Visual Function Profile)

A visual profile is a comprehensive characterization of an individual's visual capabilities across multiple dimensions, typically including visual acuity, contrast sensitivity, visual field, and color perception. In accessibility, understanding a user's visual profile is…

Visual Question Answering(also: VQA)

A task in which a system receives an image and a natural language question about that image, then generates a natural language answer. VQA emerged as a key accessibility paradigm through services like VizWiz, where blind users could submit photos with questions and receive…

Visual acuity(also: VA, LogMAR acuity, Snellen acuity)

A measure of the sharpness or clarity of vision, typically expressed as a Snellen fraction (e.g., 20/20, 20/200) or LogMAR value. A person with 20/200 vision must be 20 feet away to see what someone with normal vision sees at 200 feet. Visual acuity of 20/200 or worse in the…

Visual field loss(also: Peripheral vision loss, Scotoma, Tunnel vision)

A reduction in the area of vision that a person can see, either in the periphery (peripheral vision loss or tunnel vision) or in the center (central vision loss or central scotoma). Visual field loss is caused by conditions such as glaucoma, retinitis pigmentosa, stroke, and…

Visual guidance(also: Visual cueing, Visual highlighting)

Assistive techniques that direct a user's visual attention to relevant content through highlights, outlines, magnification, or other visual cues. For people with low vision, visual guidance systems can compensate for reduced visual acuity or restricted visual fields by making…