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Chapter 12
| Term | Definition |
|---|---|
| low vision | refers to individuals whose visual impairment is not so severe that they are unable to read print of any kind; they man read large or regular print, and they may need some kind of magnification. |
| braille | A system in which raised dats 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. |
| 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 the cornea 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. |
| vitreous humor | a transparent, gelatinous substance that fulls 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 |
| iris | the colored portion of the eye; contracts or expands, depending on the amount of light striking it. |
| visual activity | 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 sighted person can discriminate the letters; does not predict how a child will be able to read p |
| functional vision assessment | an appraisal of an individual's use of vision in everyday situations |
| refraction | the bending of light rays as they pass through the structures (cornea, aqueous humor, pupil, lens, vitreous humor) 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 excessively 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 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 or outward |
| nystagmus | a condition in which there are rapid involuntary movement of the eyes; sometimes indicates a brain malfunction and/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, and landmarks and 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 simulataneously |
| obstacle sense | a skill possessed by some people who are blind, whereby they can detect the presence of obstacles in their environments; research has shown that it is not an indication of an extra sense |
| echolocation | ability to detect objects in the environment by auditory echoes created by footsteps or tapping a cane. |
| phonological awareness | the ability to understand that speech flows can be broken into smaller units such as words, syllables, and phonemes |
| stereotypic behaviors | repetitive, ritualistic motor behaviors such as twirling, spinning objects, flapping the hands, and rocking, similar to those that are evident in some people who are blind |
| expanded core curriculum (ECC) | functional skills and competencies students with visual impairments need beyond the academic competencies for sighted students in the conventional curriculum |
| Unified English Braille (UEB) | a combination of literacy braille and braille codes for technical fields, such as the Nemeth code for science and mathematics |
| perkins brailler | 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 iis held in a slate while a stylus is pressed through openings to make indentations in the paper |
| braille bills | legislation passed in several states to make braille more available to students with visual impairment; specific provisions vary from state to state, but major advocates have lobbied for making braille available if parents want it and ensuring that |
| large-print books | books having a font size that is larger than the usual 10 point type usually 18-point type |
| magnifying devices | often recommended for people with low vision; can be for close vision or distance vision |
| long cane | a mobility aid used by individuals with visual impairment, who sweep it in a wide arc in front of them |
| tactile maps | an embossed representation of the environment that people who are blind can use to orient themselves to their surroundings |
| braille notetakers | portable devices that can be used to take notes in braille, which are then converted to speech, braille, or text |
| 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 |
| screen readers | software for computers that magnifies images on the screen and/or converts test can on the screen to speech |
| itinerant teacher service | services for students who have visual impairment in which the special education teacher visits several different schools to work with students and their general education teachers |
| accessible pedestrian signals | devices for people who are blind to let them know when the "walk" signal is on at intersections; can be auditory, tactile, or both. |
Created by:
mrutledge197