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Glossary

Acronyms 

  • AT — Assistive Technology

  • BJO — British Journal of Ophthalmology

  • CAST — Computer Assistive Technology Services (NALIS libraries)

  • CRPD — UN Convention on the Rights of Persons with Disabilities

  • CVI (Certificate) — Certificate of Visual Impairment (TTBWA)

  • DR — Diabetic Retinopathy

  • ECC — Expanded Core Curriculum

  • GBD — Global Burden of Disease

  • ICD-11 — International Classification of Diseases (11th rev.)

  • IAPB — International Agency for the Prevention of Blindness

  • IOL — Intraocular Lens (cataract surgery)

  • JAWS — Job Access With Speech (Windows screen reader)

  • MSVI — Moderate to Severe Visual Impairment

  • NALIS — National Library & Information System Authority (T&T)

  • NESTT — National Eye Survey of Trinidad & Tobago (2013–14)

  • NVDA — Non-Visual Desktop Access (free Windows screen reader)

  • O&M — Orientation & Mobility

  • ROP — Retinopathy of Prematurity

  • SI (registration) — Sight-Impairment registration (TTBWA/State)

  • SSSD — Student Support Services Division (MoE T&T)

  • TTBWA — Trinidad & Tobago Blind Welfare Association

  • UHC — Universal Health Coverage

  • WHO — World Health Organization

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A–Z Glossary

  • Accessible format (books/media) — Formats a blind/low-vision user can access (braille, DAISY, large-print, navigable audio, accessible PDF/EPUB).

  • Accommodation (reasonable) — Adjustments to environment/tools/timing enabling equal participation (e.g., accessible files, screen-reader support, extra time).

  • Age-related macular degeneration (AMD) — Macula disease causing central vision loss; reading/face recognition affected while side vision may remain.

  • Assistive Technology (AT) — Tools that enable access/independence: screen readers, magnifiers, OCR apps, braille displays, electronic magnifiers, audio wayfinding.

  • Best-corrected visual acuity (BCVA) — Acuity after optimal optical correction. (WHO surveillance typically uses presenting acuity.)

  • Blindness (WHO/ICD-11) — Worse than 3/60 (20/400) in better eye or visual field <10° around fixation.

  • Braille — Tactile system of raised dots; also via refreshable braille displays connected to computers/phones.

  • Cataract — Clouding of the eye’s lens; common, age-related; treatable with surgery (lens replaced by IOL).

  • Certificate of Visual Impairment (CVI — T&T) — Official certificate documenting low vision/blindness per WHO/ICD thresholds; supports SI registration and services.

  • Contrast sensitivity — Ability to see low-contrast targets; loss affects reading, mobility, and face recognition even if Snellen looks “okay.”

  • CRPD (UN disability treaty) — Commits states to accessibility, inclusive education, equal employment, and independent living.

  • Diabetic retinopathy (DR) — Diabetes-related retinal damage; screening + timely treatment reduce blindness risk.

  • Expanded Core Curriculum (ECC) — Skills beyond academics for students with VI: braille literacy, O&M, assistive tech, social/independent living, recreation, career, self-advocacy, sensory efficiency.

  • Field of vision / visual field — Total area seen without eye movement; measured in degrees. Constriction causes “tunnel vision.”

  • Glare sensitivity (photophobia) — Discomfort/visibility loss in bright light; common in albinism, cataract, corneal/retinal disease.

  • Glaucoma — Optic-nerve disease causing peripheral field loss first; often irreversible; control slows progression.

  • Global Burden of Disease (GBD) — International modelling of prevalence/impact; source of all-ages sight-loss estimates for T&T (2010).

  • Guide dog — Trained dog for safe mobility; availability/public-access rules vary by country.

  • Hyperopia / Myopia / Astigmatism — Refractive errors (far/near-sightedness; irregular cornea) that blur images; corrected with lenses/surgery.

  • ICD-11 vision-impairment categories (WHO) — Mild: worse than 6/12–6/18; Moderate: worse than 6/18–6/60; Severe: worse than 6/60–3/60; Blindness: worse than 3/60 or field <10°.

  • IAPB Vision Atlas — Global eye-health indicators curated by IAPB.

  • Intraocular lens (IOL) — Artificial lens implanted during cataract surgery.

  • JAWS (screen reader) — Windows screen reader that outputs speech/braille and supports full keyboard navigation.

  • logMAR — Logarithmic acuity scale; higher = worse (0.0 ≈ 20/20; 1.0 ≈ 20/200).

  • Low vision — Reduced vision not fully correctable with standard refraction and limiting daily tasks (could be acuity, field, contrast, or glare-related).

  • Marrakesh Treaty — Allows cross-border sharing of accessible books for persons who are blind/print-disabled.

  • NALIS CAST — Public-library Computer Assistive Technology Services (screen readers, magnifiers, accessible workstations).

  • NESTT — National, population-based eye survey (2013–14) for adults ≥40 in T&T; reports measured prevalence + causes.

  • NVDA (screen reader) — Free, open-source Windows screen reader; widely used in schools/workplaces.

  • OCR (optical character recognition) — Converts photos/scans of print into text for speech/braille.

  • Orientation & Mobility (O&M) — Training for safe travel: white-cane skills, spatial awareness, route planning, landmarks, navigation apps.

  • Presenting visual acuity — Acuity measured with the person’s usual correction (if any). Used for WHO surveillance.

  • Refreshable braille display — Electronic device with moving pins forming braille cells to show digital text in real time.

  • Refractive error — Focusing problems (myopia, hyperopia, astigmatism) causing blur; usually correctable.

  • Retinopathy of prematurity (ROP) — Retinal disease in premature infants; treatable if detected early.

  • Screen magnifier — Software/device that enlarges and enhances contrast (e.g., ZoomText, Windows Magnifier).

  • Screen reader — Software that speaks on-screen text and enables non-visual navigation (JAWS, NVDA, VoiceOver).

  • Sight-Impairment (SI) registration (T&T) — Eligibility-based registration of low vision/blindness to access services and grants (validated with TTBWA involvement).

  • Snellen fraction (e.g., 20/200 or 6/60) — Distance acuity notation: first number = test distance; second = distance a typical observer reads that line; higher denominators = worse.

  • Tunnel vision — Severe visual-field constriction; central island remains (e.g., advanced glaucoma).

  • Universal design / accessible design — Products/spaces/information usable by the widest range of people without special adaptation (e.g., alt text, high-contrast modes, tactile cues).

  • VoiceOver / TalkBack — Built-in screen readers on Apple (iOS/macOS) and Android devices.

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