Glossary
Terms used in accessibility research and practice. Each entry has a definition, common aliases, and category tags.
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- Late Blind(also: Adventitiously Blind, Acquired Blindness)
- A person who lost their vision later in life, typically after age 5-7 when visual memories and concepts have been established. Late blind individuals often retain visual memories and may use these to construct mental representations of spaces and routes. Research suggests late…
- Leber Hereditary Optic Neuropathy(also: LHON)
- A maternally inherited genetic condition that causes sudden or rapid loss of central vision, typically affecting young adults between the ages of 15 and 35. LHON results from mutations in mitochondrial DNA that damage the optic nerve, leading to significant bilateral central…
- Legal Blindness(also: Legally Blind)
- A level of vision loss defined in many countries as visual acuity of 20/200 or less in the better eye with best correction, or a visual field of 20 degrees or less. Legal blindness does not necessarily mean total blindness — many legally blind people have some residual or…
- Legal blindness(also: Legally blind)
- A level of visual impairment defined in many jurisdictions as visual acuity of 20/200 or worse in the better eye with best correction, or a visual field of 20 degrees or less. Legal blindness is an administrative threshold used to determine eligibility for disability benefits…
- Legally Blind(also: Legal Blindness)
- A legal classification of visual impairment used to determine eligibility for government benefits, rehabilitation services, and disability accommodations. In the United States, legal blindness is defined as visual acuity of 20/200 or worse in the better eye with best correction,…
- Line Chart Accessibility(also: Accessible Line Graphs, Chart Accessibility)
- The practice of making line charts and graphs perceivable and understandable by people with visual impairments through alternative representations such as tactile graphics, sonification, speech descriptions, or multimodal interfaces. Accessible line charts must convey not just…
- Link Preview(also: Link Destination Preview, Link Target Preview)
- Information about the content or nature of a hypertext link's destination page, provided to users before they follow the link. Link previews help users make informed navigation decisions, reducing the costly trial-and-error of following links to discover their content and then…
- Live Description(also: Real-Time Description, Live Audio Description)
- The practice of providing descriptions of visual content in real time as events unfold, as opposed to scripted descriptions added during post-production of recorded media. Live description is used in contexts such as livestreaming, live theatre, sporting events, and…
- Livestream Accessibility(also: Live Video Accessibility)
- The practice of making live video broadcasts accessible to people with disabilities, particularly viewers with visual or hearing impairments. Livestreams present unique accessibility challenges because they feature multiple simultaneous visual elements (main video, webcams,…
- LogMAR(also: Logarithm of the Minimum Angle of Resolution)
- A standardised scale for measuring visual acuity based on the logarithm (base 10) of the minimum angle of resolution, used in the Bailey-Lovie eye chart and widely adopted in clinical vision research. A logMAR value of 0.0 corresponds to 20/20 (6/6) vision, with higher values…
- Lookout(also: Google Lookout)
- An Android accessibility application developed by Google that uses the smartphone camera and machine learning to identify objects, read text, scan documents, and describe surroundings for blind and partially sighted users. Lookout can identify currency, read food labels,…
- Low Vision(also: Partial Sight, Partially Sighted)
- A visual impairment that cannot be fully corrected by glasses, contact lenses, medication, or surgery, but where some usable vision remains. Low vision encompasses a wide range of conditions and severity levels, typically defined as visual acuity between 20/70 and 20/400 in the…
- Low vision(also: Partial sight, Visual impairment)
- A level of visual impairment that cannot be fully corrected with standard glasses, contact lenses, medication, or surgery, but retains some usable vision — distinguishing it from total blindness. Low vision encompasses a range of conditions affecting acuity, visual field,…
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