The term “learning disability” is defined as a central nervous system dysfunction which interferes with the brain’s capacity to process information in a conventional manner. The disorder is intrinsic to the individual and is presumed to be due to central nervous system dysfunction. People with specific learning disabilities exhibit disorders in one or more of the basic psychological processes involved in understanding or using spoken or written language. These may be manifested in disorders of listening, thinking, talking, reading, writing, spelling, or arithmetic. Learning disabilities may occur concomitantly with other handicapping conditions (eg. Social or emotional disturbance), or environmental influences (eg. Socioeconomic disadvantage), but are not the direct result of these conditions or influences.
When an individual performs functions such as writing letters or numbers, remembering visually based material, or numbers from the blackboard, visual perceptual skills are being used. Visual perception, or visual information processing, is an active process in which a group of visual cognitive skills is used for extracting and organizing visual information from the environment. This information is integrated with other sensory modalities and higher cognitive functions. Other terms such as “perceptual motor”, “visual spatial”, and “visual motor”, have been used to describe similar skills.
It is well documented in the literature that there is a link between visual information processing and learning. The optometrist’s role is to diagnose and manage visual problems that interfere with the learning process.
Children’s primary vision care examinations should assess visual acuity and refraction (hyperopia, inn particular, is positively correlated with poor reading ability), visual efficiency skills (binocularity, oculomotor efficiency and accommodative functions), and ocular health. A thorough case history is a very important part of the oculo-visual assessment and will help to identify those who are in need of a visual perceptual assessment.
The case history should cover the broad range of adaptive behaviours which may be manifested by children or adults with learning – related problems. An evaluation of visual perceptual skills can be made when indicated.
The impact of visual information processing problems is more likely to be felt in the primary grades (kindergarten through grade three), when children are learning to read. These skills are considered readiness skills that are important for many school based activities. The impact of visual efficiency problems is more likely to be felt in higher grade levels (grade three and above) when the emphasis shifts from learning to read, to reading to learn.
A recommendation for visual perception therapy should be based on a sound diagnostic evaluation. Visual perceptual skills to be evaluated should include the following:
Fine motor skills – The ability to perform fine motor tasks that require visual guidance e.g. printing.
Spatial orientation – The ability to orient oneself in space. Includes laterality (an internal understanding of right and left) and directionality (the ability to externally differentiate right from left).
Visual form perception – The ability to discriminate a visual form that is incomplete (closure), hidden (figure-ground), disorganized (organization), or broken apart (assembly).
Visual Memory – The ability to remember visual information after presentation for a short period of time. There are two types of visual memory: visual sequential memory (remembering the sequence of objects, letters, words, etc.), and visual spatial memory (remembering the location of the visual stimulus).
Spatial relations – The process of analysis and synthesis of a visual stimulus. Includes spatial visualization, spatial perception, spatial reasoning, and visual imagery.
Visual-motor integration – The ability to integrate the perception of a complex visual stimulus with fine motor skills in order to accurately reproduce a stimulus (e.g. design copying).
Auditory-visual integration – The ability to equate a temporally distributed auditory stimulus (tapping pattern) with a spatially distributed visual match.
“Dyslexia” is a term which currently enjoys a variety of definitions. As a result, the term has little meaning with the exception of “reading difficulty”. The World Federation of Neurology defined dyslexia as follows: “A disorder manifested by difficulty in learning to read despite conventional instruction, adequate intelligence, and socio-cultural opportunity.
It is dependent upon fundamental cognitive disabilities which are frequently of constitutional origin”. More recent definitions of the different subtypes of dyslexia distinguish it from non-specific forms of reading disability. Diagnostic test currently exist which enable optometrists to identify the various forms of dyslexia. It is important to recognize that while dyslexia may be present in individuals with visual perceptual deficits and/or visual efficiency problems, the deficits are not the cause of the dyslexia.
There are many controversial methods for the treatment of learning difficulties. Any therapies prescribed must be based on the results of a sound diagnostic evaluation. We do not endorse unproven methods of treatment, but rather, support a multi-disciplinary approach to the treatment and remediation of visually-related learning problems. The multi-professional team may include the following professions: optometry, medicine, psychology, education, occupational therapy, audiology, speech therapy, and social work.
Pamela Schmitz, BSc. O.D.
Pamela Andrews, O.D.