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Tyler Pollock Ch.12
Chapter 12
| Term | Definition |
|---|---|
| legally blind | A person who has visual acuity of 20/200 or less in the better eye even with correction or has a field of vision so narrow that its widest diameter subtends an angular distance no greater that 20 degrees. |
| low vision | A term used by educators to refer to individuals whose visuals impairment is not so severe that they are unable to read print of any kind; they may read large or regular print , and they may need some kind of magnification. |
| braille | A system in which raised dots allow people who are blind to read with their fingertips; each quadrangular cell contains from one to six dots, the arrangement of which denotes different and symbols. |
| cornea | A transparent cover in front of the iris and pupil in the eye; responsible for most of the refraction of light rays in focusing on an object. |
| aqueous humor | A watery substance between thecornea and lens of the eye. |
| pupil | The contractile opening in the middle of the iris of the eye. |
| lens | A structure that refines and changes the focus of the light rays passing through the eye. |
| iris | The colored portion of the eye; contracts or expands, depending on the amount of light striking it. |
| vitreous humor | A transparent, gelatinous substance that fills the eyeball between the retina and the lens of the eye. |
| retina | The back portion of the eye, containing nerve fibers connected to the optic nerve. |
| optic nerve | The nerve at the back of the eye, which sends visual information back to the brain. |
| visual acuity | The ability to see fine details; usually measured with the Snellen chart. |
| Snellen chart | Used in determining visual acuity; consists of rows of letters or Es arranged in different positions; each row corresponds to the distance at which a normally sighed person can discriminate the letters |
| functional vision assessment | Evaluation that consists of finding out the consquences and setting events that maintain inappropriate behaviors. |
| refraction | The bending of light rays as they pass through the structures of the eye. |
| myopia | Nearsightedness; vision for distant objects is affected; usually results when eyeball is too long. |
| hyperopia | Farsightedness; vision for near objects is affected; usually results when the eyeball is too short. |
| astigmatism | Blurred vision caused by an irregular cornea or lens. |
| glaucoma | A condition often, but not always, due to excessive pressure in the eyeball; the cause is unknown; if untreated, blindness results. |
| optic nerve | The nerve at the back of the eye, which sends visual information back to the brain. |
| cataracts | A condition caused by clouding of the lens of the eye; affects color vision and distance vision. |
| diabetic retinopathy | A condition resulting from interference with the blood supply to the retina; the fastest-growing cause of blindness. |
| cortical visual impairment (CVI) | A poorly understood childhood condition that apparently involves dysfunction in the visual cortex; characterized by large day-to-day variations in visual ability. |
| retinopathy of prematurity (ROP) | A condition resulting from administration of an excessive concentration of oxygen at birth; causes scar tissue to form behind the lens of the eye. |
| optic nerve hypoplasia (ONH) | A condition resulting in underdevelopment of the optic nerve; often accompanied by brain abnormalities, which can result in other problems; one of the most common causes of childhood blindness. |
| retinitis pigmentosa | A hereditary condition resulting in degeneration of the retina; causes a narrowing of the field of vision and affects night vision. |
| tunnel vision | A condition characterized by problems in peripheral vision, or a narrowing of the field of vision. |
| night blindness | A condition characterized by problems in seeing at low levels of illumination; often caused by retinitis pigmentosa. |
| strabismus | A condition in which the eyes are directed inward (crossed eyes) or outward. |
| nystagmus | A condition in which there are rapid involuntary movements of the eyes; sometimes indicates a brain malfunction &/or inner-ear problems. |
| orientation and mobility (O&M) | The ability to have a sense of where one is in relation to other people, objects, & landmarks & to move through the environment. |
| cognitive mapping | A nonsequential way of conceptualizing the spatial environment that allows a person who has visual impairment to know where several points in the environment are simultaneously |
| obstacle sense | A skill possessed by some people who are blind, whereby they can detect the presence of obstacles in their environments; it is the result of learning to detect subtle changes in the pitches of high-frequency echoes. |
| echolocation | Ability to detect objects in the environment by auditoru echoes created by footsteps, tapping a cane, clicking one's tongue. similar to sonar, the echoes can be used to interpret the location & size of objects. |
| phonological awareness | The abililty to understand that speech flow can be broken into smaller sound units such as words, syllables, and phonemes; lack of such awareness is generally thought to be the reason for the reading problems of many students with learning disabilities. |
| stereotypic behaviors | Repetitive , ritualistic motor behavoirs such as twirling, spinning objects, flapping the hands, & rocking, similar to those that are evident in some people who are blind. |
| Expanded Core Curriculum | functional skills & competencies students with visual impairments need beyond the academic competencies for sighted students in the conventonal curriculum, such as independent living, orientation & mobility, sensory efficiency, & social interaction skills |
| Unified English Braille (UEB) | A combination of literary braille and braille codes for technical fields, such as the Nemeth Code for science and mathematics; not yet widely adopted. |
| Perkins Brailer | A system that makes it possible to write in braille; has six keys, one for each of the six dots of the cell, which leave an embossed print on the paper. |
| slate and stylus | A method of writing in braille in which the paper is held in a slate while a stylus is pressed through openings to make indentations in the paper. |
| braille bills | Legislation passed to make braille more available to students with visual impairment; major advocates have lobbied for making braille available if parents want it, ensuring that teachers of students with visual impairment are proficient in braille |
| large-print books | Books having a font size that is larger than the usual 10-point type; a popular size for large-print books is 18-point type. |
| magnifying devices | Often recommended for people with low vision; can be for close vision (e.g., handheld magnifier) or distance vision (e.g., monocular telescope or binocular telescope mounted on eyeglass frames). |
| tactile map | an embossed representation of the environment that people who are blind can use to orient themselves to their surroundings. |
| long cane | A mobility aid used by individuals with visual implairment, who sweep it in a wide arc in front of them; proper use requires considerable training; the mobility aid of choice for most travelers who are blind. |
| NFB-Newsline | A free service available through the National Federation of the Blind; allows individuals to access magazines and newspapers 24 hours a day from any touch-tone telephone. |
| Descriptive Video Service | A service for use of people with visual impairment that provides audio narrative of key visual elements; available for several public television programs and some videos of movies. |
| braille notetakers | A system in which raised dots allow people who are blind to read with their fingertips; each quadrangular cell contains from one to six dots, the arrangement of which denotes different letters and symbols. |
| screen readers | Software for computers that magnifies images on the screen and/or converts text on the screen to speech. |
| itinerant teacher service | Services for students who have visual impairment in which special education teacher visits several different schools to work with students & their general education teachers; students attend their local schools & remain in general education classrooms. |
| curriculum-based measurement (CBM) | A formative evaluation method designed to evaluate performance in the curriculum to which students are exposed; usually involves giving students a small sample of items from the curriculum in use in their schools |
| Accessible pedestrian signals (APSs) | Devices for people who are blind to let them know when the "walk" signal is on at intersections; can be auditory, tactile, or both. |
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