The treatment of dyslexia is currently based on speech therapy regimens. Scientific analysis of the results is inadequate with regard to the frequency and severity of this disorder. It seems that treatment is more successful when the rehabilitation is intensive and specifically adapted to the child’s difficulties. Programs for intensive stimulus of phonological skills have been proposed. They have proven to be difficult to implement due to the constraints of organization in schools, and improving phonological skills is not followed by an automatic improvement in reading performance.97
The finding of multiple dysfunctions in the dyslexic (“constellation dys”) often leads to reinforcement of speech therapy with additional therapies: psychomotor skills, psychology etc.
In the visual sphere, it is essential that all dyslexics receive comprehensive ophthalmological examinations, including cycloplegia, to uncover masked hyperopia as well as to perform a detailed analysis of ocular motility and accommodative power. All refractive disorders must be corrected since they may aggravate difficulties in decoding, and they can impede attention by excessively soliciting accommodation.
The improvement of visual capture of written language was initially oriented towards oculomotor rehabilitation with reeducation of convergence insufficiency when present, which is often the case.47
A literature review conducted in 2006 by Granet et al99
has shown that this treatment improves comfort and reading time, but does not directly improve the possibilities of decoding and comprehension.98
Ocular motility recordings showing that the visual axes converge excessively sometimes, demonstrating the need for a study analyzing the dyslexic’s divergence in order to best guide the possibilities for vergence therapy.56
The cost of these video–graphic techniques is the main obstacle to their use.
Orthoptic rehabilitation inspired by “behavioral vision therapy” is sometimes proposed when there are disturbances in saccades or in pursuit (the ability to visually locate and follow an object) in the dyslexic. No scientific study has shown the merits of this therapy which, in the absence of routine use of video–oculography, singularly video–oculography, fails primarily due to the lack of specific criteria for evaluation of disturbances of saccades and pursuit in the dyslexic.100
The American Academy of Ophthalmology recommended against this type of training in its report from 2011 due to the weakness of the statistical data found in various studies. This attitude, however, is highly controversial. First, the criteria are very difficult to implement due to the heterogeneity of the dyslexic population. Secondly, it is sometimes difficult to separate poor readers from dyslexics in the first stages of learning to read.101
Stein et al44
proposed to correct the effects of unstable binocular vision in the dyslexic by the use of monocular occlusion during reading. The study was conducted with a group of 143 dyslexic children, aged 7 to 11 years, with no known ophthalmologic problem but with unstable binocular control on the Dunlop test. All the children were asked to wear slightly tinted yellow glasses (in order to address the hypothetical presence of a disorder of the magnocellular system), and the left eye of 71 of the participants was occluded while reading or writing. After 3 months, the binocular control was stabilized for 59% of the children in the unilateral occlusion group compared to only 36% in the other group. This stabilization was accompanied by a significant improvement in reading ability (the reading delay was decreased by 9.4 months), which then continued at a slower pace for a total improvement of 16.1 months in the occluded group compared to 8 months for the group without occlusion (follow-up of 9 months).
Iovino et al103
evaluated the use of red and blue tinted glasses, which are thought to increase contrast and enhance the functioning of the magnocellular system. The study examined 60 subjects in the 8- to 18-year age range with no visual anomaly; only 15 of the participants were dyslexic while the other 15 were classified as reading–spelling–arithmetic disabled. Of the remaining 30 children, half were arithmetic-disabled and the other half had an attention deficit/hyperactivity disorder without learning disabilities. The advantage of this sampling was to introduce comorbidities to the study of the effect of colored overlays on dyslexics. All of the subjects had to do two reading tests using black letters: the Word Identification subtest of the Woodcock Reading Mastery Test-Revised104
(a word recognition task) and the Formal Reading Inventory105
(a reading comprehension task). The text was covered with either a red, blue, or no overlay. The blue overlay wavelengths ranged from 380 nm to 580 nm and had a peak wavelength of 480 nm, whereas the red wavelengths ranged from 640 nm to 780 nm with a peak wavelength of 700 nm. For the reading recognition test, no effects of overlays were found with any of the colors. For the reading comprehension test, almost 60% of the children showed slight to significant improvement. A contrast analysis was conducted to separate out the effect of each color. Iovino et al103
found that 57% of all of the children saw an increase in their performance with the blue filter, while 37% presented a decrease in their score. When using the red filter, the contrast analyses revealed that the use of this overlay did not significantly affect reading comprehension accuracy, even though 13 of the 60 children presented a clear improvement in their performance. However, when the authors used the reading recognition latency as a covariate in the repeated measures model (in order to evaluate the effects of decoding ability on reading comprehension skills), the effect of both colors was not significant. The authors concluded that “there was no evidence that visual overlays had a beneficial, differential effect on reading skills in reading-spelling disabled children.”103
The use of tinted lenses was initially proposed in a much more personalized mode for the Irlen Syndrome (also known as visual stress, Meares–Irlen syndrome, and scotopic sensitivity syndrome), which could affect 15% of the general population and 45% of children with a learning disorder.106
Patients would then have impaired visual perception to certain wavelengths of light. These disturbances, undetectable by the usual visual examinations, would be responsible for a “visual stress” with difficulties of fixation, abnormal fatigue, migraines, and moodiness.107
The very existence of Irlen syndrome is debatable, even though a recent f-MRI study shows functional abnormalities in regions treating visual and sensory information.108
Treatment is based on individually prescribed colored filters, either tinted spectacle lenses or colored overlays, that filter wavelengths that are poorly supported by the patient as determined by personalized testing. Evaluation of this technique has yielded conflicting results and it is not available everywhere in the world.109
The American Academy of Pediatrics notes that the studies performed to investigate the condition are often of poor quality. Ritchie et al107
conducted the most recent assessment in 2011. It should be noted that at the outset, this test was performed on children judged to be below-average readers who had not undergone a common assessment that would have proven them to be dyslexic. The group included 57 children whose reading skill levels were assessed using the Wilkins Rate of Reading and the Gray Oral Reading tests. Orthoptic examination complemented these tests. The diagnosis of Irlen syndrome was made in 44 of 57 children (77%). Children in this group performed the reading test twice with an overlay adapted to their cases, selected (if possible) from the complementary portion of the spectrum, and with a colorless overlay. Children free of signs of Irlen syndrome were evaluated under the same conditions, the color overlays being chosen to ensure that the two groups had homogenous color distributions. A mixed-design analysis of variance was performed on the Wilkins Rate of Reading Test scores, with the between-subject factor of group (non-Irlen/Irlen) and the within-subject factor of the overlay condition. The main effect of the group was not significant. There was no significant effect of overlay condition or an interaction between the factors. The authors conclude that colored overlays, whether of the prescribed color or not, did not facilitate reading rate compared with a colorless overlay.
Postural treatment, also called “proprioceptive treatment,” proposes suppression of the very low amplitude vertical heterophorias observed in dyslexics.110
This is accomplished using prisms of 1 to 3 diopters oriented toward the axis of action of the oblique muscles. Vertical heterophorias are considered to be the vertical component of cyclophorias secondary to hypotonia of the superior oblique muscles, their tonus being highly dependent on postural reflexes. The algorithm for the prescription of postural prisms is based on visual and postural clinical criteria.54
Prisms are complemented with orthopedic insoles, instructions concerning the best posture while reading, and exercises destined to regulate the function of various muscle groups. A double-blind study, with a group of 16 treated and 14 control dyslexics followed for 6 months, showed a significant improvement in global leximetric testing in reading regular words and irregular words, as well as in tests of orthographic decision making. On the other hand, there was no significant improvement with regard to all tests concerning phonological awareness.55
These results, obtained from a study of only 30 dyslexics, have yet to be confirmed.
One of the first additional studies, measuring postural constants during attention, suggested that the treatment might act by modifying the dyslexic’s capacities for attention.111
In this study, the postural parameters of 27 dyslexics (12 untreated and 15 treated, with the postural regimen for 3 months; mean age: 11.6 ± 2.1 years, 12.5 ± 1.5 years, and 10.6 ± 1.7 years, respectively) were compared with 12 nondyslexic children. All of the children had to remain motionless on a force plate while either fixating on one point or performing a silent reading task (a Stroop test, which requires significant cognitive effort). The mean velocity of the center of pressure displacement was only increased in the reading task for the dyslexic group. For the treated children, in 13 of 15 patients, an inverse tendency was observed with a mean velocity similar to those observed for the control children. Other authors have reached different conclusions using a very similar protocol.112
It is possible that this difference is due to the fact that the study examined older dyslexics with postural characteristics closer to those of adults (age range of 14–17 years). Other researchers, in examining the effect of a dual task on postural control in dyslexic children, studied 18 dyslexic children (mean age 10.3 ± 1.2 years) who were compared with 18 nondyslexic children of similar ages, seemed to have confirmed that dyslexic children are significantly more unstable during the reading task compared with a simple reflex horizontal and vertical saccades task.113
This postural instability could indicate that such children lack the integration of multiple sensorimotor inputs.
A newer protocol on a large cohort (123 children) seems to confirm that, like auditory and visual sensory information, the integration of proprioceptive information is different in dyslexic children.5
Thirty dyslexic and 51 treated dyslexic children (3 months of treatment with low-power prisms cancelling small vertical heterophoria) were compared with 42 nondyslexic children. Two conditions were compared: co-85 Hz vibration at the ankles versus the absence of vibrations with, for each of the conditions, the use of two different attention tasks (ie, fixing a single point, or counting large or small stars within a range of stars of different sizes and drawn on a standard A4 sheet). Postural balance was recorded on a force platform. The results indicate that the average speed of the center of pressure in the presence of vibrations at 85 Hz (compared to the condition without vibration) is significantly increased in children with either treated or untreated dyslexia. This result is obtained regardless of the attention task requested. Without vibration, the attention performance of the treated group was similar to that of the control group, even though the performance was significantly degraded in the untreated group. These results suggest that the integration of proprioceptive signals during postural control as well as the attentional ability are both actually altered in children with dyslexia. The results also show that, during postural control, the attention ability of an individual with dyslexia rejoins the level of the normal reader after proprioceptive treatment.
Some physical characteristics of a text can play a role in the decoding used for reading. Zorzi et al have shown that for the Times Roman size 14 font, increasing the space between the letters to 2.7 points – which is associated with a proportional increase in the spaces between words and between lines – can significantly increase the reading speed of certain dyslexics.114
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