Abacus

Accommodation -The eyes’ ability to adjust itself to see things at different distances. This happens because the lens in the eye changes shape allowing images to focus clearly on the retina.

Acuity- measurement of the sharpness of vision as it relates to the ability to discriminate detail.

Add- This is the "bifocal" part of glasses. The add is generally "added" to a persons’ distance prescription to help him focus better for reading and other near tasks.

Amsler grid- A hand held card featuring horizontal and vertical lines, usually white on black background, used to test for central visual field defects.

Assistive Technology- any item, piece of equipment, or product system, whether acquired commercially off the shelf, modified, or customized, that is used to increase, maintain, or improve functional capabilities of individuals with disabilities.
 

Best Corrected Visual Acuity- The acuity that results from the best possible refraction/lens correction.

Bifocals-The combination of two lenses into one. This is generally done with the distance prescription at the top of the lens with addition diopters of power at the bottom of the lens for reading and other near tasks.

Binocular Vision-The ability to use both eyes at the same time to focus on the same object. The images of both eyes are fused into a single image in the brain. This provides depth perception.

Blind, Blindness- A broad term meaning unable to see. Total blindness specifically means no ability to see any light. Legal blindness is a much broader term that includes vision loss ranging from total blindness to having very usable residual vision. The definition of legal blindness in the United States is: 1) central visual acuities of 20/200 or less in the better eye after best correction; and/or a reduction of visual fields of 20 degrees -or less in the better eye.

Braillers - used for producing Braille. Perkins is a manual brailler. An embosser is an electronic brailler.

Central Visual Acuity- The vision (acuity) measured from the fovea and macula, "straight ahead vision".

CF- count fingers

Closed circuit televisions- (CCTV)- electronic magnification that produces the image onto a monitor- CCTVs are available to each classroom at ISVI.

Contrast- the differences in a visual target and its background.

Convergence- The process of having the eyes focus together on a object held close to the them causing the eyes to turn inward towards the nose, maintaining a single image of the object in the brain.

Correction-The wearing of glasses/lenses that correct refractive errors in the eyes.

Depth perception- The ability to perceive the relative positions of things in space.

Diopter- The unit of measurement used to indicate how much light rays are refracted, or bent, by a lens.

Eccentric viewing- Ability in such a way that the operative part of the retina is able to view, i.e., turning the head or head tilt.

ENUC- enucleated

Eye dominance- When one eye tends to take over the major function of seeing.

Floaters- Small particles of cells, fibers, etc., which move around in the vitreous.

Focus- Bringing all light rays into a point by the use of a lens. The cornea, lens, and fluids inside the eye work together to bring light rays into focus on the retina with the lens doing the "fine focusing".

Franklin Speller or Language Master- A talking dictionary/thesaurus- gives definitions, spellings, and example in sentences.

Fusion- The ability to combine the two images produced by each eye into a single mental image.

Glare-An annoying sensation produced by too much light in the visual field that can cause both discomfort and reduction in visual acuity.

Glasses- Bifocals and reading glasses should be worn for all near activities- Distance glasses are usually worn full time unless specified. Broken glasses should be sent to Low Vision Coordinator to be fixed or the health center to send to LVC or optical to be repaired.

HM- hand motion

Intraocular pressure- The fluid pressure within the eye created by the continual production and drainage of aqueous fluid in the anterior chamber.

Learning Media- an individual’s primary learning channel; one or more of the primary senses that an individual uses most for learning; the best and most efficient literacy medium.

Legal blindness- In the US, visual acuity of 20/200 or worse in the better eye with corrective lenses OR visual field restricted to 20 degrees diameter or less in the better eye.

LP-Light perception- The ability to distinguish the absence from the presence of light.

Light projection- The ability to determine the direction of the source of light.

Low Vision- A visual impairment after correction but with potential for use of available vision, with or without optical or non-optical compensatory visual strategies, devices, and environmental modifications, to plan and perform daily tasks.

Magnifiers- increases the size of the image- used for reading print, studying maps, viewing diagrams in mathematics books--there are different powers.
 

Monocular- Using one eye. Monocular telescopes are used for distance viewing to bring image closer to the eye.

Motility- Eye movement controlled by the extra ocular muscles.

Near Point of Accommodation- The closest point at which the eye can still focus (accommodate) on an object clearly. The point varies from person to person depending on age, refractive errors present, etc.

Near Vision- The ability to see things clearly at a normal reading distance (about 14 16 inches or 35 -40 centimeters) from the eye.

Night blindness- A condition where a person may be able to see with no problems by day or in good illumination (light), but is unable to see at night or in faint light. Can be caused by any eye condition that affects the rods.

NLP- No Light Perception- the total absence of vision.

Non-optical devices- devices or modifications that do not involve optics, used to make visual information more accessible to individuals with low vision, such as book stands, trays, positioning seating, modifications of illumination, and large print when indicated.

Null point- Eye position or direction of gaze in which oscillation is reduced.

Ocular- Having to do with the eye.

Ocular pursuit- The act of tracking a moving object in all cardinal directions- vertical, horizontal, oblique, and circular.

OD- right eye

Ophthalmologist-A medical physician who specializes in the medical and surgical care of the eyes and is qualified to prescribe ocular medications, diagnoses eye conditions and to perform surgery on the eyes.

Ophthalmoscope- An instrument used in examining the interior of the eye.

Optic Nerve- It is the essential link between the eye and brain. It carries impulses for vision from the retina to the brain.

Optician-A person who grinds lenses, fits them into a frame, and adjusts the frame to the wearer.

Optometrist- A physician who specializes in refractive errors, prescribes eyeglasses or contact lens and diagnoses and manages conditions for the eye.

Orthoptics-The series of planned eye exercises used to develop or restore the normal teamwork of the extraocular muscles of the eyes.

Orientation and Mobility-specialized teaching to visually impaired including the use of a cane, dog guide, electronic travel aids and sighted guide techniques.

OS- left eye

OU- both eyes

Peripheral vision-the perception of objects or motion outside the direct line of vision. ("side vision")

Prosthesis-Used here specifically for an artificial eye. More generally, it means any -artificial part of the body.

Pupil-The circular opening in the iris that allows light to pass through to the retina. The pupil dilates, or becomes larger, to allow more light to enter the eye when lighting conditions are low. The pupil constricts, or becomes smaller, to reduce the amount of light entering the eye with lighting conditions are high. The size of the pupil is controlled by the iris.

Reading Stands- Bring work closer to the eyes for optimum reading angles and lighting. Reduces neck and back pain from bending down to the desk to read.

Refraction-1.The deviation or bending of rays of light when passing from one clear substance into another of a different density.
2 . The determination of refractive errors in the eye and their correction with lenses.

Refractive Error- A defect in the eye that prevents light rays from coming to a single focus exactly on the retina.

Retina- The innermost layer of the eye mostly made up of nerve fibers and rods/cones. Somewhat similar to the film in a camera.

Rx- prescription

SC- without correction

Slate and stylus- a small pocket sized device for producing Braille in limited quantities and is a useful device in situations where the student does not have access to a brailler.

Snellen Chart- Test chart for assessing visual acuity. Usually tested at 20ft. Low vision charts are used for more exact assessments for nearer distance.

Tape Recorders- For listening to audio cassettes, to take notes, record lessons, do assignments, answer questions and complete exams.

Thermoforms- heated formed raised lines on special paper.

Typoscope- a black piece of template with a slit to block out all but the line of print that can be viewed through the slit and increasing contrast for the print that is exposed. It limits the amount of information shown at one time.

UTT- unable to test

Visual abilities- the dimension of functional vision that includes visual acuity, visual fields, motility, brain function-control, and light color perception.

VA-Visual acuity- The measurement of the eye’s ability to distinguish the shapes and details of objects at a designated distance.

Visual clutter- a combination of images and backgrounds that provide distracting details for some individuals who are unable to select a single object from its background.

Visual Fields- the area that can be seen when looking straight ahead; the entire area without shifting the eyes or moving the head.

Visual Functioning- how individuals use their ability to see and interpret what is seen.

Visual Impairment- a visual loss, after correction, that affects an individual’s ability to perform tasks of daily life, caused by the visual system that is not working properly or not formed correctly.

Visual perceptual skills- this refers to the process of attaching meaning to a visual image. These skills encourage the use of attending, (fixating), tracking, shifting attention between objects, scanning, and reaching for objects. Visual perception occurs in the brain and it must be determined whether the deficit skills are caused by the visual impairment or a related brain-based perceptual problem.