Page 7 - Cahier-Pratical- Low-Vision-De-2014.indd

1. Visual Impairment Visual Impairment © Essilor International Practical Low Vision Figure 1: “Seeing poorly” can take many forms. Visual impairment creates a particularly incapacitating disabi- a. Disorders of the central vision generally cause loss of visual lity that considerably reduces the potential for cultural, artistic, acuity in both distance and near vision, frequently associated professional and learning experiences. It compromises people’s with a central scotoma - i.e. full loss of vision in a def ned area safety in their movements and also their effectiveness in daily of the central f eld of vision -, impaired perception of colours life. It destroys their quality of life. The impairment often results or depth, inability to read or write, loss of precise hand-eye from age-related diseases that can be neither treated nor cured. coordination and an incapacity to recognise faces. They give Gradually or suddenly, they destroy certain parts of the eye and rise to diff culties in directing one’s gaze and sensations of loss irremediably impair the vision of the person. of balance when walking. A person is referred to as visually impaired if his/her binocular b. Disorders of the peripheral vision cause a reduction in the f eld visual acuity is less than 20/60 (6/18) and it cannot be impro- of vision that can reach the stage of - extremely reduced - tunnel ved by conventional means such as spectacles, contact lenses or vision, impair the perception of movement and affect night vision refractive surgery. and the ability to recognise shapes and contours. They can affect spatial orientation to the point of creating a partial or total inability Thanks to prevention and screening, diseases causing blindness in to move around. children and young adults tend to be less common. On the other side of the spectrum, there is an increased incidence of age related c. General disorders comprise the disruptions caused by both types conditions affecting our ageing population. of impairment mentioned above. They create physiologically signif cant impairments. We will come back to this. These various ocular conditions, discussed later, will affect the person’s sight in different ways. We are accustomed to saying that there are “several types of poor vision” and that a person can There are three phenomena that should be mentioned here because experience very different problems, depending on their general they are independent of the type of impairment and affect the great situation and the conditions under which the symptoms develop. majority of people with sight loss : glare, the phenomenon of completion Depending on where alterations take place, quite specif c functional and the psychological factor. disorders arise, highlighted by the assessments that we present in sections 2 B and 4 B. 7 Copyright © 2013 ESSILOR ACADEMY EUROPE, 13 rue Moreau, 75012 Paris, France - All rights reserved – Do not copy or distribute. Copyright © 2013 ESSILOR ACADEMY EUROPE, 13 rue Moreau, 75012 Paris, France - All rights reserved – Do not copy or distribute.