In order to have a good visual system the following skills are required:
- Quality of vision: it is the capacity to see in a clear and comfortable way.
- Eye health: A healthy eye is that which does not suffer from any pathology. In this case Pathology involves all those eye disorders that require surgical or pharmaceutical treatment.
- VA (Visual Acuity): it is the capacity to distinguish details. It values the quantity of vision we have with glasses, contact lenses or without.
When the quantity of vision is not 100% and it might be due to the following refractive defects:
Myopia: difficulty in focusing at far sight. The image is formed in front of the retina.
Visual analysis ability: Capacity of analyzing and distinguishing visual information. Shapes, figure-shape, visual memory (it is difficult to write a dictation well if we do not have memory to retain information), etc...
Audiovisual integration: it relates visual stimulus (letter) with hearing stimulus (phoneme). This will lead to reading with rhythm.
Visuomotor integration: Eye-hand coordination. It is the work we do when copying from the blackboard to the paper.
Hyperopia: difficulty in focusing at near sight. The image is formed behind the retina.
Astigmatism: blurred vision, because the contours are not clearly perceived. The image is formed in different parts of the retina.
Visual efficiency: In order to have good efficiency first we have to reach a good vision quality and after that a good functioning of the following abilities:
Accommodation: These are the quick and precise focusing changes that the visual system makes in order to see clearly at different distances. An example is when looking from the blackboard to the paper and vice versa, or in order to see the car controls and the road.
Binocular vision: It is the integration of images from both eyes to the brain. This brings about the three-dimensional vision.
When there is not good binocular vision the reasons may be:
Strabismus: eye misalignment produces crossed eyes. Eye is seen turned; it may turn in or out.
Foria: deviation is not shown, but there is a constant effort to keep the eyes aligned.
Amblyopia (lazy eye): One eye or both do not have a 100% Visual Acuity. It is not correctable or improvable with glasses or contact lenses. It can be caused by many causes: strabismus, different graduation from one eye to the other, congenital cataracts,...
Ocular motility: These are the little movements produced by the eyes in order to fix on an object, letter, word or sentence. Those movements make possible quick and efficient reading.
Information processing: Visual information is processed at the brain level in a central zone: visual cortex. Still, there are some 30 brain areas which are connected with that one and also among them. Therefore good information processing is important.
The capacity to decode and to use visual information is related to the following abilities:
Visual-space ability: localization of the objects in the space. If we do not have a good perception it will be difficult to learn: right – left, up – down. Therefore we will also confuse p – b – d, etc...
Visual analysis ability: Capacity of analyzing and distinguishing visual information. Shapes, figure-shape, visual memory (it is difficult to write a dictation well, if we do not have memory to retain information), etc...
Audiovisual integration: it relates visual stimulus (letter) with hearing stimulus (phoneme). This will lead to reading with rhythm.
Visuomotor integration: Eye-hand coordination. It is the work we do when copying from the blackboard to the paper.
