On-line study materials: Special Education 1

Terminology

Visual acuity

  • acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain

Normal vision

  • If you have 20/20 vision, it means that when you stand 20 feet away from the chart you can see what a "normal" human being can see. (In metric, the standard is 6 meters and it's called 6/6 vision). In other words, if you have 20/20 vision your vision is "normal" -- a majority of people in the population can see what you can see at 20 feet. If you have 20/40 vision, it means that when you stand 20 feet away from the chart you can only see what a normal human can see when standing 40 feet from the chart.

Low vision

  • a loss of eyesight that makes everyday tasks difficult or impossible, affecting central and/or peripheral (side) vision

Blindness

  • the condition of lacking visual perception due to physiological or neurological factors

Partially sighted

  • In the United States, the terms "partially sighted", "low vision", "legally blind" and "totally blind" are used by schools, colleges, and other educational institutions to describe students with visual impairments.
  • indicates some type of visual problem, with a need of person to receive special education in some cases.

Errors of refraction

  • error in the focusing of light by the eye and a frequent reason for reduced visual acuity

Nearsightedness (myopia)

  • A person is able to see near objects well and has difficulty seeing objects that are far away. Light rays become focused in front of the retina. This is caused by an eyeball that is too long, or a lens system that has too much power to focus.
  • corrected with a concave lens

Farsifhtedness (hyperopia)

  • A person is able to see distant objects well and has difficulty seeing objects that are near. Light rays become focused behind the retina. This is caused by an eyeball that is too short, or by a lens system that has too little focusing power.
  • corrected with a convex lens

Binocular vision

  • vision in which both eyes are used together

Having two eyes confers at least four advantages over having one:

  • First, it gives a creature a spare eye in case one is damaged.
  • Second, it gives a wider field of view.
  • Third, it gives binocular summation in which the ability to detect faint objects is enhanced.
  • Fourth, it can give stereopsis in which binocular disparity provided by the two eyes' different positions on the head give precise depth perception.

Spatial and tactual skills

  • The ability to locate objects in three dimensional world using touch.

Remaining sight

  • Motor skills

    • learned sequencea of movements that combine to produce a smooth, efficient action in order to master a particular task

  • Long cane

    • This "traditional" white cane, also known as a "Hoover" cane, after Dr. Richard Hoover, is designed primarily as a mobility tool used to detect objects in the path of a user. Cane length depends upon the height of a user, and traditionally extends from the floor to the user's sternum. Some organisations favor the use of much longer canes.

 

 

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