من طرف Thae Use of Tinted Lenses and Colored Overlays for the Treatment of Dyslexia and Other Related Reading and Learning Disorders
Over the past two decades the use of tinted lenses and colored overlays to improve reading comfort and performance has been presented in both the popular media and professional literature. With increasing frequency, patients and parents consult optometrists about the value of colored overlays and tinted lenses. Meares1 and later Irlen2 described a syndrome of visual symptoms and distortion that can be alleviated with colored filters. This syndrome has been referred to as "scotopic sensitivity syndrome" or the Irlen Syndrome.3 Colored overlays and tinted lenses are purported to improve reading ability and visual perception, increase sustained reading time, and eliminate symptoms associated with reading such as light sensitivity, eyestrain, headaches, blurring of print, loss of place, and watery eyes.
A comprehensive review of the available scientific literature regarding the effectiveness of tinted lenses or filters revealed the following:
There is evidence that the underlying symptoms associated with the Irlen Syndrome are related to identifiable vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions, in many patients seeking help from colored lenses.4-7 Furthermore, such conditions return to normal function when appropriately treated with lenses, prisms, or vision therapy. When patients exhibiting the Irlen Syndrome were treated with vision therapy, their symptoms were relieved. These patients were no longer classified as exhibiting this syndrome, and therefore did not demonstrate a need for the colored overlays or tinted lenses.4
Most investigators have not controlled for the presence of vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions. In most cases, researchers have simply assumed that a history of a previous eye examination ruled out any significant vision problem.8-14 Others have developed a protocol to screen for vision problems but have not included an adequate battery of tests to eliminate common accommodative, binocular, and ocular motor dysfunctions.3, 15-19
The results of prospective, controlled research on the effectiveness of tinted lenses or colored overlays vary. One randomized, controlled trial demonstrated that children with reading difficulties, who were prescribed filters based on colored overlays, experienced reduced symptoms of asthenopia.15 While this study suggests the color may need to be individually and precisely prescribed, another study demonstrated significantly improved eye movements among reading disabled children when reading through blue filters.20 Other researchers failed to find improvement in comprehension scores in readers using tinted lenses.4
Results of testing utilized to determine the most appropriate color are not repeatable.21, 22 There are numerous variables within the individual and the environment (such as differences in lighting between the home and various classrooms) that can influence the effectiveness of assigned overlays. It has been reported that up to twenty-five percent of the time, children who receive tinted lenses need to have their tints adjusted within the first year.23