Visual Impairment Definition According to the US Department of Education (2006), Visual Impairment including blindness means an impairment in vision that, even with correction, adversely affects a child’s educational performance. The term includes both partial sight and blindness.(p.1265)
Blindness Definition A person, who is blind according to the Centers for Disease Control (2005), has a visual acuity worse than 20/400, with the best possible correction, or visual field of 10 degrees or less. (p.1)
Low Vision Definition Corn (1989) stated that low vision is a level of vision, with standard correction hinders an individual in planning and/ or execution of a task, but which permits enhancement of the functional vision through the use of optical or nonoptical devices, environmental modifications and /or techniques. (p.28)
Legally Blind Definition The American Foundation for the Blind stated that legally blind is when the central visual acuity of 20/200 or less in the better eye, with best correction, or a diameter of normal field that does not subtend or angle greater than 20 degrees at its widest point. (p.1)
Visual Efficiency Definition Visual efficiency- This is how well people can use their sight. It is influenced by many factors, including the person’s acuity and peripheral vision, environmental conditions and psychological variables.
Residual Vision Residual vision – the amount and degree of vision a person has functional use of, despite a visual disability.
Peripheral Vision Peripheral vision is the width of a person’s field of vision, or the ability to perceive objects outside of the direct line of vision. This aspect of vision helps people to move freely through their environment. It helps them to see large objects and movement. Severe limitations in peripheral vision is sometimes called tunnel vision or restricted central vision.
Categories of Visual Impairment Normal acuity Impaired acuity Normal vision field Impaired peripheral fields Impaired lower visual field “Blind spots” in the visual field Blind
Visual Acuity Visual acuity is how well a person can see at various distances.
Activity 1 Based on the information received, identify the different types of visual impairment in the pictures below.