Learning Disabilities, Dyslexia, and Vision

Number: 0078

Table Of Contents

Policy
Applicable CPT / HCPCS / ICD-10 Codes
Background
References

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Policy

Scope of Policy

This Clinical Policy Bulletin addresses learning disabilities, dyslexia, and vision.

1. Experimental, Investigational, or Unproven

   Aetna considers the following procedures experimental, investigational, or unproven because the effectiveness of these approaches has not been established:

   1. Visual training and behavioral vision therapy for members with dyslexia and/or learning disabilities;

      As indicated in a policy statement developed jointly by the American Academy of Pediatrics (AAP), American Academy of Ophthalmology (AAO), the American Association for Pediatric Ophthalmology and Strabismus (AAPOS), and the American Association of Certified Orthoptists (2009), there is no known eye or visual cause for dyslexia and learning disabilities and no effective visual treatment. Multi-disciplinary evaluation and management must be based on proven procedures demonstrated by valid research.
      

   2. ChromaGen lenses for improvement of learning skills in children with dyslexia
   3. Colored filtered/tinted lenses for treatment of dyslexia or learning disabilities
   4. MoveR training (an immersive therapy to reinforce visual discrimination, visual attention, saccadic/vergence system and spatial orientation) for improvement in visual perceptual skills in dyslexic children
   5. Music-based interventions for individuals with learning disabilities
   6. Non-invasive brain stimulation (including transcranial direct current stimulation) for the treatment of dyslexia.

2. Related Policies

   • CPB 0321 - Visual Perception Training and Vision Restoration Therapy
   • CPB 0489 - Vision Therapy

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Table:

CPT Codes / HCPCS Codes / ICD-10 Codes

Code	Code Description
CPT codes not covered for indications listed in the CPB:
MoveR training – no specific code
90867	Therapeutic repetitive transcranial magnetic stimulation (TMS) treatment; initial, including cortical mapping, motor threshold determination, delivery and management
90868	subsequent delivery and management, per session
90869	subsequent motor threshold re-determination with delivery and management
92065	Orthoptic and/or pleoptic training, with continuing medical direction and evaluation
HCPCS codes not covered for indications listed in the CPB:
ChromaGen lenses - no specific code
A4541	Monthly supplies for use of device coded at E0733
E0733	Transcutaneous electrical nerve stimulator for electrical stimulation of the trigeminal nerve
G0176	Activity therapy, such as music, dance, art or play therapies not for recreation, related to the care and treatment of patient's disabling mental health problems, per session (45 minutes or more) [Music based intervention for individuals with learning disabilities]
ICD-10 codes not covered for indications listed in the CPB (not all-inclusive):
F48.9	Nonpsychotic mental disorder, unspecified
F63.81 - F63.89	Other impulse disorders
F70 - F79	Intellectual disabilities
F80.0 - F81.9	Specific developmental disorders of speech, language and scholastic skills
F84.0	Autistic disorder
F90.0 - F90.9	Attention-deficit hyperactivity disorder
H54.7	Unspecified visual loss
R27.0 - R27.9	Other lack of coordination
R41.840 - R41.89	Other specific cognitive deficit
R48.0	Dyslexia and alexia
R48.1 - R48.8	Other symbolic dysfunction

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Background

The issue of learning disorders, including dyslexia, has become a matter of increasing personal and public concern.  Inability to read and comprehend is a major obstacle to learning and may have far-reaching social and economic implications.  Concern for the welfare of children with dyslexia and learning disabilities has lead to a proliferation of diagnostic and remedial treatment procedures, many of which are controversial.  This policy statement addresses these issues, which are of importance to affected individuals, their families, teachers, doctors, allied health personnel, and society.

1. early comprehensive educational, psychological, and medical assessment; and
2. educational remediation combined with appropriate psychological and medical treatment. 

Although it is obvious some children do not read well because they have trouble seeing, research has shown that the majority of children and adults with reading difficulties experience a variety of language defects that stem from complex, altered brain morphology and function, and that the reading difficulty is not due to altered visual function per se.

However, in spite of these facts, a certain number of children who experience reading difficulty may also experience a treatable visual difficulty in addition to their learning dysfunction.  Doctors can identify the majority of those who have reduced visual acuity.  However, in a small percentage of children, a visual abnormality such as farsightedness may not be detected during pediatric office screening procedures.  Therefore, doctors who evaluate children for reading difficulties should consider referral to an ophthalmologist familiar with children's eye problems.

In their position statement on learning disabilities, dyslexia, and vision, the American Academy of Pediatrics (AAP), American Academy of Ophthalmology (AAO), and American Association for Pediatric Ophthalmology and Strabismus (AAPOS) concluded the following:

1. Those considered to be at risk for learning disabilities, dyslexia or attention defects, should be thoroughly assessed by both educational and psychological specialists.
2. Learning disabilities, including dyslexia and other forms of reading or academic under-achievement, require a multidisciplinary approach to diagnosis and treatment, involving educators, psychologists, and physicians.  Research has established that the basis of dyslexia and other specific learning disabilities is within the central nervous system and is multi-factorial and complex.
3. Unfortunately, however, it has become common practice among some to attribute reading difficulties to one or more subtle ocular or visual abnormalities.  Although the eyes are obviously necessary for vision, the brain interprets visual symbols.  Therefore, correcting subtle visual defects can not alter the brain's processing of visual stimuli.  Children with dyslexia or related learning disabilities have the same ocular health statistically, as children without such conditions.  There is no peripheral eye defect that produces dyslexia or other learning disabilities and there is no eye treatment that can cure dyslexia or associated learning disabilities.
4. Ocular defects should be identified as early as possible and when correctable, managed by the ophthalmologist.  If no ocular defect is found, the child should be referred to a primary care physician to coordinate required multi-disciplinary care.
5. Eye defects, subtle or severe, do not cause reversal of letters, words, or numbers.  No scientific evidence supports claims that the academic abilities of dyslexic or learning disabled children can be improved with treatment based on
   1. visual training, including muscle exercises, ocular pursuit, tracking exercises, or "training" glasses (with or without bifocals or prisms);
   2. neurological organizational training (laterality training, crawling, balance board, perceptual training), or
   3. tinted or colored lenses.
   Some controversial methods of treatment result in a false sense of security that may delay or even prevent proper instruction of remediation.  The expense of these methods is unwarranted, and they can not be substituted for appropriate remedial educational measures.  Claims of improved reading and learning after visual training, neurological organization training, or use of tinted or colored lenses, are typically based upon poorly controlled studies that rely on anecdotal information or testimony.  These studies are frequently carried out in combination with traditional educational remedial techniques.
6. Since remediation may be more effective during the early years, early diagnosis is paramount.  The educator ultimately plays the key role in providing help for the learning disabled or dyslexic child or adult.

In a review on the applicability and effectiveness of eye exercises, Rawstron et al (2005) noted that eye exercises have been purported to improve a wide range of conditions such as vergence problems, ocular motility disorders, accommodative dysfunction, amblyopia, learning disabilities, dyslexia, asthenopia, myopia, motion sickness, sports performance, stereopsis, visual field defects, visual acuity, and general well-being.  Small controlled studies as well as a large number of case reports support the treatment of convergence insufficiency.  Less robust evidence indicates visual training may be useful in developing fine stereoscopic skills and improving visual field remnants following traumatic brain injury.  The authors concluded that, as yet, there is no clear scientific evidence published in the mainstream literature supporting the use of eye exercises in the remainder of the areas reviewed, and their use therefore remains controversial.

A technology assessment of vision therapy by the Institute for Clinical Systems Improvement (ICSI, 2003) concluded that available studies provide inadequate evidence of the effectiveness of vision therapy for learning disabilities.

Irlen syndrome (also known as scotopic sensitivity syndrome) is a visual-perception dysfunction that is thought to contribute to dyslexia and learning disabilities.  The syndrome was identified by California psychologist Helen Irlen, who published a book called Reading by the Colors, and, since 1983, has been marketing red and blue non-prescription eyeglasses to dyslexics.  A number of Irlen Clinics have been opened around the country.

Skottun and Skoyles (2008) stated that it has been suggested that dyslexia is the result of a deficit in rapid sensory processing.  Several methods have been used to assess this with regards to vision: temporal contrast sensitivity, visual persistence, temporal order judgments, temporal acuity, and coherent motion.  These investigators examined these methods and found that several of them – visual persistence, temporal order judgments, and coherent motion – are poorly suited to evaluating the dynamic aspects of vision.  In the case of temporal contrast sensitivity and temporal acuity the results from these tests either are conflicting or provide little support for an impairment.  As far as vision is concerned there is little evidence for a specifically temporal deficit.

Kruk et al (2008) noted that the potential role of visual processing deficits in reading difficulty was brought to public attention by claims that a large proportion of children with dyslexia suffer from a perceptual dysfunction currently referred to as Meares-Irlen syndrome (MISViS).  A previous study showing that visual perceptual measures involving visual memory and discrimination predict independent variance in reading achievement provided a basis to examine their relationships with the diagnostic criteria of MISViS.  This study examined these visual processing characteristics in 8- to 10-year old children (n = 36), half of whom were experiencing reading difficulty.  Children were assessed for MISViS by Irlen screeners; approximately 50 % of the participants in each group were positively identified.  Concurrent performance on standardized visual processing tests showed that while a positive diagnosis of MISViS is not indicative of reading ability, nor in particular of a visual-processing deficit subtype identified by Watson and Willows, MISViS can indicate visual processing difficulties potentially related to visual attention inefficiency.

Hawelka and Wimmer (2008) stated that in 2 previous studies they assessed the difficulty of dyslexic readers with letter string processing by using variants of the partial report paradigm, which requires report of a letter name in response to a position cue.  The poor dyslexic performance was interpreted as evidence for a visual-attentional deficit of dyslexic readers.  In the present study, these researchers avoided verbal report by using a task that only required the detection of pre-defined targets (e.g., letters or pseudo-letters) in strings.  On this purely visual task, the dyslexic readers did not differ from non-impaired readers.  This finding speaks against a basic visual-attentional deficit; rather it suggests that the dyslexic deficit on partial report paradigms stems from a problem in establishing a string representation which includes position and name codes.

Pieh and Lagrèze (2008) stated that Irlen therapy, visual training, training of ocular motor control, and the correction method of HJ Haase represent a diversity of treatment methods that are mainly aimed at dyslexia, fatigue while reading, and general lack of concentration.  These investigators summarized the theoretical background of these methods, treatment approaches, and related clinical trials.  None of these methods, because of incorrect theoretical concepts and an attempt to simplify the underlying causes, was found to have a specific influence on the patients' complaints.  The absence of specific therapeutic effects, the high costs, and time expenditure required should discourage practitioners from recommending these methods.

Von Suchodoletz (2010) stated that a wide variety of methods based on very different concepts are available to treat children with dyslexia.  Basically, symptomatic and causal principles can be distinguished. Among the symptomatic methods are systematic programs based on learning theory, in which reading and spelling or precursors of these abilities are directly trained.  Causal methods promise pronounced and persistent improvement of reading and spelling abilities through elimination of the postulated reason underlying the learning disabilities.  Among the causal methods are treatment programs that train low-level functions.  Such training is based on the assumption that deficits of auditory, visual or kinesthetic perception, of motor skills or of the coordination of cerebral functional areas are at the bottom of specific learning disabilities.  Concepts of other causal methods act on the assumption that learning processes are blocked or that abnormal medical conditions or psychiatric disorders constitute the background of dyslexia.  The author reviewed treatment concepts for children with dyslexia in the German-speaking countries and the methods of treatment derived from the different concepts.  It is emphasized that effectiveness is proven only for symptomatic training programs but not for causal methods.

Quercia et al (2013) noted that developmental dyslexia affects almost 10 % of school-aged children and represents a significant public health problem.  Its etiology is unknown.  The consistent presence of phonological difficulties combined with an inability to manipulate language sounds and the grapheme-phoneme conversion is widely acknowledged.  Numerous scientific studies have also documented the presence of eye movement anomalies and deficits of perception of low contrast, low spatial frequency, and high-frequency temporal visual information in dyslexics.  Anomalies of visual attention with short visual attention spans have also been demonstrated in a large number of cases.  Spatial orientation is also affected in dyslexics who manifest a preference for spatial attention to the right.  This asymmetry may be so pronounced that it leads to a veritable neglect of space on the left side.  The authors concluded that the evaluation of treatments proposed to dyslexics whether speech or oriented towards the visual anomalies remains fragmentary.

Ramsay et al (2014) stated that dyslexia affects 5 % to 8 % of the population of the Western world.  While reading, different eye movements are required.  Compared to other persons, dyslexics have more and longer fixations, shorter saccade amplitude, a higher percentage of regression, and more fixation disparity when reading.  In non-reading situations, dyslexics do not have more binocular problems than others.  These researchers examined if computerized orthoptic vergence training could improve reading ability for dyslexic children.  The study was conducted at an elementary school exclusively for dyslexic children.  A total of 12 subjects, aged 13 to 14 years, were trained with RetCorr, a computerized vergence training program.  Reading speed was assessed before and after treatment.  The results were compared with an age-matched control group.  The dyslexic subjects conducted on average 11.75 sessions (± 2.53 standard deviation [SD]) of orthoptic training over a 5-week period.  On average, the number of words read per minute before training were 87.83 (± 16.80 SD) and after training 95.58 words (± 18.08 SD).  The difference was statistically significant (p = 0.0066).  In the control group, the change was from 85.00 (± 19.68 SD) words to 89.37 words (± 19.71 SD) over the same time period.  This difference was not significant (p = 0.1235).  The authors concluded that most scientists agreed that dyslexia is mainly a phonological impairment.  Nevertheless, the results showed that vergence treatment might help dyslexics. They stated that larger studies are needed to provide guidance in this area.

Creavin and co-workers (2015) explored associations between specific learning disorder with impairment in reading (dyslexia) and ophthalmic abnormalities in children aged 7 to 9 years.  Cross-sectional analysis was performed on cohort study data from the Avon Longitudinal Study of Parents and Children.  Reading impairment was defined according to Diagnostic and Statistical Manual of Mental Disorders, 5fth Edition criteria.  Children who achieved greater than 2 SD below the mean in the Neale Analysis of Reading Ability Scale II and level less than 4 in non-mathematical national key stage 2 tests were defined as having severe reading impairment (SRI); children with blindness or IQ less than 70 were excluded.  Data were available for 5,822 children, of whom 172 (3 %) met the criteria for SRI.  No association was found between SRI and strabismus, motor fusion, sensory fusion at a distance, refractive error, amblyopia, convergence, accommodation, or contrast sensitivity.  Abnormalities in sensory fusion at near were mildly higher in children with SRI compared with their peers (1 in 6 versus 1 in 10, p = 0.08), as were children with stereo-acuity worse than 60 seconds/arc (1 in 6 versus 1 in 10, p = 0.001).  The authors concluded that 4 of every 5 children with SRI had normal ophthalmic function in each test used.  A small minority of children displayed minor anomalies in stereo-acuity or fusion of near targets.  They stated that the slight excess of these children among those with SRI may be a result of their reading impairment or may be unrelated.  These investigators found no evidence that vision-based treatments would be useful to help children with SRI.

1. specific to recognition of multi-character arrays as wholes rather than of individual characters within arrays,
2. specific to characters' position within arrays rather than to characters' identity, or revealed only under a higher attention load due to
   1. low-discriminable characters, and/or
   2. characters' short exposure. 

Furthermore, in this study these investigators examined whether pure dyslexic participants who do not have attention disorder exhibit a reduced VAS. Although co-morbidity of dyslexia and attention disorder is common and the ability to sustain attention for a long time plays a major rule in the visual recognition task, the presence of attention disorder was neither evaluated nor ruled out in previous studies. The authors concluded that the findings of this study did not reveal any differences between the performance of dyslexic and control participants on 8 versions of the visual recognition task. They stated that these findings suggested that pure dyslexic individuals do not present a reduced visual attention span.

Colored Filtered/Tinted Lenses

There is considerable controversy over whether the treatment of dyslexia with colored lenses is effective, or whether the Irlen syndrome truly exists; Available evidence is of poor quality, with inconsistent results.

A systematic evidence review (Albon et al, 2008) concluded that there is insufficient evidence of the effectiveness of colored lenses for dyslexia. "Meta-analysis and qualitative assessment of eight included RCTs did not show that the use of coloured filters led to a clear improvement in reading ability in subjects with reading disability.  It was not possible to comment on whether coloured filters can improve symptoms of visual stress that may be associated with reading disability due to a lack of available evidence.  Based on the evidence obtained from this systematic review there can be no major implications for current practice in the treatment of reading disability.  It remains a possibility that there exists a subgroup of people who may experience an improvement in reading through the use of coloured filters, while others find that there is no beneficial effect.  Further well-designed research may generate clearer results".

A policy statement issued by the AAP's Committee on Children with Disabilities, AAO, and AAPOS (1992) stated that "visual problems are rarely responsible for learning difficulties.  No scientific evidence exists for the efficacy of eye exercises, vision therapy, or the use of special tinted lenses in the remediation of these complex pediatric neurological conditions".

In a joint statement on learning disabilities, dyslexia, and vision, the AAP, AAO, AAPOS, and the American Association of Certified Orthoptists (2009) stated that most experts believe that dyslexia is a language-based disorder.  Vision problems can interfere with the process of learning; however, vision problems are not the cause of primary dyslexia or learning disabilities.  Scientific evidence does not support the effectiveness of eye exercises, behavioral vision therapy, or special tinted filters or lenses for improving the long-term educational performance in these complex pediatric neurocognitive conditions.  Diagnostic and treatment approaches that lack scientific evidence of efficacy, including eye exercises, behavioral vision therapy, or special tinted filters or lenses, are not endorsed and should not be recommended.

1. a treatment (n = 46) and
2. a without-treatment group (n = 36). 

Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home).  The tests were first undertaken without the yellow filter.  With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereo-acuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute).  The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children.  After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed.  Over the 3 months, the 2 groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed.  However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p = 0.01).  The authors concluded that no effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties.  The yellow filter had no effect even in children with low MAA and BAF.  The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant. Ritchie and colleagues (2011) examined the effectiveness of Irlen colored overlays for alleviating reading difficulties ostensibly caused by Irlen syndrome, a proposed perceptual disorder with controversial diagnostic status.  A total of 61 schoolchildren (aged 7 to 12 years) with reading difficulties were assessed by an Irlen diagnostician.  These researchers used a within-subject study design to examine differences in reading rate across 3 conditions:

1. using an overlay of a prescribed color;
2. using an overlay of a non-prescribed color; and
3. using no overlay. 

In a subset of 44 children, all of whom had a diagnosis of Irlen syndrome, these researchers also used a between-group design to test the effects of Irlen colored overlays on a global reading measure.  The Irlen diagnostician diagnosed Irlen syndrome in 77 % of poor readers.  These researchers found no evidence for any immediate benefit of Irlen colored overlays as measured by the reading-rate test or the global reading measure.  The authors concluded that the findings of this study suggested that Irlen colored overlays did not have any demonstrable immediate effect on reading in children with reading difficulties.

Kusano and associates (2015) stated that Irlen syndrome is a proposed perceptual processing disorder characterized by visual distortions while reading.  Patients with this syndrome may experience light sensitivity, visual stress, and other related problems such as dyslexia.  Tinted lenses and colored overlays have been designed to help individuals with the symptoms of Irlen syndrome.  However, there is still debate over the effectiveness of these interventions and whether this syndrome actually exists.  In this report, these investigators described a case involving an 8-year old girl with dyslexia who experienced severe visual hyper-sensitivity and whose symptoms completely resolved after wearing tinted lenses.  While it is possible that she experienced a psychogenic visual disturbance that was relieved because of the placebo effect, the clinical course of her symptoms matched the findings previously described by Irlen.  The patient was unable to read without tinted lenses.  With tinted lenses, she could read at the appropriate age level, suggesting that her difficulty was due to a problem in optical information processing.  The concepts underlying Irlen syndrome are vaguely defined, and several groups insist that the visual stress associated with this syndrome might be responsible for dyslexia as well as other disorders.  These ambiguous criteria may be responsible for the criticism over the validity of this condition.  Although this was only an anecdotal case, the patient exhibited the core functional deficit described in Irlen syndrome and showed a dramatic improvement with tinted lenses; therefore, this case may facilitate investigations into the mechanism underlying Irlen syndrome, if it actually exists.  The authors concluded that although further studies are needed to confirm the validity of this syndrome and the therapeutic approach, Irlen syndrome should be recognized as a disorder since its symptoms can be easily relieved by wearing tinted lenses or color filters.

Vision Therapy for the Treatment of Learning Disabilities

Rucker and Phillips (2018) stated that traditional orthoptic therapy used by ophthalmologists, orthoptists, and optometrists is directed at improving visual acuity, ocular alignment, or both.  For example, convergence exercises are used to treat convergence insufficiency (CI).  However, other forms of "vision therapy" are directed at improving "visual processing and efficiency".  The therapeutic regimen often entails repetitive ocular motor tasks performed during multiple office visits with a behavioral optometrist.  These ocular motor tasks are used to treat diverse conditions such as learning disabilities, poor reading ability, dyslexia, and attention-deficit hyperactivity disorder (ADHD).  These investigators reviewed the evidence regarding the effectiveness of therapy directed at ocular motility for the treatment of multiple conditions.  Randomized, controlled, double-masked studies showed that convergence exercises reduced symptoms and improved signs of CI in otherwise healthy patients.  However, the most effective convergence tasks, and the optimal duration and frequency of these tasks, remain unknown.  Patients with learning disabilities, poor reading ability, dyslexia, or ADHD do not consistently have unique ocular motor deficits.  Patients who acquire ocular motor deficits do not develop these conditions.  There are no randomized controlled trials (RCTs) that showed treatment consisting of repetitive ocular motor tasks improved learning disabilities, reading, dyslexia, or ADHD.  The authors concluded that convergence exercises effectively treated CI in healthy patients; the optimal treatment regimen is unknown.  Moreover, they stated that there is insufficient evidence to recommend "vision therapy" for the treatment of learning disabilities, impaired reading, dyslexia, or ADHD.

Hussaindeen and colleagues (2018) reported the frequency of binocular vision (BV) anomalies in children with specific learning disorders (SLD) and evaluated the efficacy of vision therapy (VT) in children with a non-strabismic binocular vision anomaly (NSBVA).  The study was performed at a center for learning disability (LD).  Comprehensive eye examination and binocular vision assessment was carried out for 94 children (mean (SD) age of 15 (2.2) years) diagnosed with specific learning disorder; BV assessment was done for children with best corrected visual acuity (BCVA) of greater than or equal to 6/9 - N6, co-operative for examination and free from any ocular pathology.  For children with a diagnosis of NSBVA (n = 46), 24 children were randomized to VT and no intervention was provided to the other 22 children who served as experimental controls.  At the end of 10 sessions of VT, BV assessment was performed for both the intervention and non-intervention groups.  Binocular vision anomalies were found in 59 children (62.8 %) among which 22 % (n = 13) had SBVA and 78 % (n = 46) had a NSBVA.  Accommodative in-facility (AIF) was the commonest of the NSBVA and was found in 67 %, followed by convergence insufficiency (CI) in 25 %.  Post-VT, the intervention group showed significant improvement in all the BV parameters (Wilcoxon signed rank test, p < 0.05) except negative fusional vergence.  The authors concluded that NSBVA is the commonest among the spectrum of ocular disorders in children with specific learning disorders.  These anomalies could potentially be an added hindrance to the reading difficulty in this special population.

The authors stated that the drawbacks of this study included an absence of masked examiner as the same optometrist was involved in the administration of VT and assessment of BV parameters pre- and post-VT.  However, it was made sure that baseline BV parameters were not looked into until post-VT assessment was carried out.  Also the pre-post-VT comparison in each subgroup of NSBVA was ideal to comment about the efficacy of VT for each specific anomaly; but as the sample size of the subjects was lesser in the sub groups, these researchers had represented this as overall NSBVA.

Rucker and Phillips (2018) stated that traditional orthoptic therapy used by ophthalmologists, orthoptists, and optometrists is directed at improving VA, ocular alignment, or both.  For example, convergence exercises are used to treat CI.  However, other forms of VT are directed at improving "visual processing and efficiency".  The therapeutic regimen often entails repetitive ocular motor tasks performed during multiple office visits with a behavioral optometrist.  These ocular motor tasks are used to treat diverse conditions such as LDs, poor reading ability, dyslexia, and ADHD.  These investigators reviewed the evidence regarding the efficacy of VT directed at ocular motility for the treatment of multiple conditions.  Randomized, controlled, double-masked studies showed that convergence exercises reduced symptoms and improved signs of CI in otherwise healthy patients.  However, the most effective convergence tasks, and the optimal duration and frequency of these tasks, remain unknown.  Patients with LDs, poor reading ability, dyslexia, or ADHD do not consistently have unique ocular motor deficits.  Patients who acquire ocular motor deficits do not develop these conditions.  There are no RCTs that showed treatment consisting of repetitive ocular motor tasks improved LDs, reading, dyslexia, or ADHD.  The authors concluded that convergence exercises effectively treat CI in healthy patients; but the optimal therapeutic regimen is unknown.  Moreover, these researchers stated that there is insufficient evidence to recommend VT for the treatment of LDs, impaired reading, dyslexia, or ADHD.

Raghuram and associates (2018) noted that developmental dyslexia (DD) is a specific learning disability of neurobiological origin whose core cognitive deficit is widely believed to involve language (phonological) processing.  Although reading is also a visual task, the potential role of vision in DD has been controversial, and little is known about the integrity of visual function in individuals with DD.  In a prospective, uncontrolled, observational study, these researchers evaluated the frequency of visual deficits (specifically vergence, accommodation, and ocular motor tracking) in children with DD compared with a control group of typically developing (TD) readers.  This trial was carried out from May 28 to October 17, 2016, in an out-patient ophthalmology ambulatory clinic among 29 children with DD and 33 TD children.  Primary outcomes were frequencies of deficits in vergence (amplitude, fusional ranges, and facility), accommodation (amplitude, facility, and accuracy), and ocular motor tracking (Developmental Eye Movement test and Visagraph eye tracker).  Among the children with DD (10 girls and 19 boys; mean [SD] age of 10.3 [1.2] years) and the TD group (21 girls and 12 boys; mean [SD] age of 9.4 [1.4] years), accommodation deficits were more frequent in the DD group than the TD group (16 [55 %] versus 3 [9 %]; difference = 46 %; 95 % confidence interval [CI]: 25 % to 67 %; p < 0.001).  For ocular motor tracking, 18 children in the DD group (62 %) had scores in the impaired range (in the Developmental Eye Movement test, Visagraph, or both) versus 5 children in the TD group (15 %) (difference, 47 %; 95 % CI: 25 % to 69 %; p < 0.001).  Vergence deficits occurred in 10 children in the DD group (34 %) and 5 children in the TD group (15 %) (difference, 19 %; 95 % CI: -2.2 % to 41 %; p = 0.08).  In all, 23 children in the DD group (79 %) and 11 children in the TD group (33 %) had deficits in 1 or more domain of visual function (difference, 46 %; 95 % CI: 23 % to 69 %; p < 0.001).  The authors concluded that these findings suggested that deficits in visual function were far more prevalent in school-aged children with DD than in TD readers, but the possible cause and clinical relevance of these deficits were uncertain.  Moreover, they stated that further study is needed to determine the extent to which treating these deficits could improve visual symptoms and/or reading parameters.

Da Silva Miyasaka and colleagues (2019) noted that scotopic sensitivity syndrome, later called Meares-Irlen syndrome or simply Irlen syndrome (IS) has been described as symptoms of poor reading ability as a consequence of poor color-matching and distorted graphic images.  Individuals with IS are considered slow, ineffective readers with low comprehension and visual fatigue.  It is still unclear if the disease pathophysiology is an independent entity or part of the dyslexia spectrum.  Nevertheless, treatments with lenses and colored filters have been proposed to alleviate the effect of the luminous contrast and improve patients' reading performance.  However, no evidence of treatment effectiveness has been achieved.  These investigators attempted to obtain evidence regarding IS etiology, diagnosis and intervention efficacy.  They carried out a systematic review covering the available studies on IS, examining the available data according to their level of evidence, focusing on diagnostic tools, proposed interventions and related outcomes.  The data showed high heterogeneity among studies, and lack of evidence on the existence of IS and treatment effectiveness.  The authors concluded that IS as described, as well as its treatments, require further strong evidence.

Temelturk and Ozer (2022) stated that given the increased evidence suggesting the presence of binocular coordination deficits in dyslexia, investigations of binocular eye movements are beneficial to clarify the underlying causes of reading difficulties.  In a systematic review, these investigators reviewed the available evidence via the examination of binocular coordination in children with dyslexia by describing the normative development of stable binocular control, and outlined future directions.  Boolean expressions in the PubMed search were used to define papers.  Following a literature search and selection process, a total of 25 studies were included.  Studies using binocular eye-tracking during linguistic and non-linguistic tasks in children with dyslexia and typical development 5 to 17 years of age were reviewed.  The studies reviewed provided consistent evidence of poor binocular coordination in children with dyslexia; however, the findings associated with different task characteristics were less consistent.  The authors concluded that the relation between binocular coordination deficits and reading difficulties needs to be further elucidated in longitudinal design with large samples entailing wide age range that may provide future treatments targeting the binocular viewing system in dyslexia.

Omar et al (2023) noted that dyslexia is a learning disability associated with reading difficulties in children.  Due to the potential of poor school outcomes, interventions have been used to aid dyslexic students read.  In a prospective, interventional study, these researchers identified the sustainability of the effect of combined visual tracking magnifier (VTM) and Ministry of Education (MOE) interventions, and MOE intervention alone on the reading performance of dyslexic school children after discontinuation of intervention.  This trial was carried out on primary school children with dyslexia aged 8 to 11 years.  Subjects underwent comprehensive ophthalmic and optometric examinations and were categorized into groups A, B, and C, comprising primary school children at level 1 or 2.  Groups A and B received combined VTM and MOE interventions for 12 and 24 weeks, respectively, and group C received MOE intervention alone.  The reading performance was evaluated at baseline and 12, 24, and 36 weeks post-intervention.  Both components of the reading performance improved significantly for school children at both levels in all study groups (all p < 0.05); however, the reading performance improvement was only about 28 % in group C and 38 % to 50 % in groups A and B.  In group A, students at level 1 showed significantly improved reading speed from baseline to 12 weeks post-VTM intervention and reading rate from baseline to 24 weeks post-VTM intervention (both p < 0.05).  Students at level 2 showed significantly improved reading speed and rate from baseline to 12 and 24 weeks post-VTM intervention (all p < 0.05).  In group B, students at both levels showed significantly improved reading speed and rate from baseline to 24 and 36 weeks post-VTM intervention (all p < 0.05).  Students at level 2 showed significantly improved reading speed 12 weeks after cessation of intervention (at 36 weeks post-VTM intervention) compared to 24 weeks post-VTM intervention (p < 0.05).  The improvement remaining stable 12 weeks after discontinuation of intervention indicated a sustained effect.  The authors concluded that combined or individual intervention improved the reading performance of dyslexic school children at levels 1 and 2; however, combined intervention demonstrated a better reading improvement effect.  Improvement in the reading performance was maintained after discontinuation of the VTM intervention.  Moreover, these researchers stated that further interventional studies with a longer study period after discontinuation of this optical intervention are needed to confirm the long-term sustainability of its positive effects on the reading performance of dyslexic school children.

The authors stated that, to the best of their knowledge, this was the 1st study examining the sustainability of the positive effects of combined VTM and MOE interventions in comparison with the MOE intervention alone on the reading performance of dyslexic children after discontinuation of the intervention to ensure the durability of the improved reading performance.  However, these investigators failed to include other interventions (e.g., cognitive training or the multi-sensory method) for comparisons, which would have yielded more robust conclusions.  Furthermore, these researchers failed to examine the durability of the observed positive effects on the reading performance of dyslexic children after entering the upper elementary grades, and follow-up studies would clarify more aspects of the effectiveness of this intervention.  These researchers stated that including students without dyslexia along with those with dyslexia in future interventional studies with a longer follow-up after discontinuation of the VTM intervention could provide more conclusive results regarding the sustainability of the positive effects.

Music-Based Interventions for Individuals with Learning Disabilities

Rushton et al (2023) noted that music is motivational, accessible and engaging for individuals with learning disabilities.  Several systematic reviews have addressed the effects of music activity on individuals with learning disabilities; however, none has specifically reviewed the use of musical activity in persons with profound and multiple learning disabilities.  In a systematic review, these investigators identified peer-reviewed studies and described the characteristics of evidence-based musical activity used in persons with profound and multiple learning disabilities.  Furthermore, these researchers examined the effectiveness of these music-based interventions and identified gaps within current research.  They carried out a systematic search in April 2021 identifying 7 peer-reviewed studies that included music-based interventions with at least 1 person with profound and multiple learning disabilities.  Results showed that interventions varied in their frequency, duration and content.  The outcome of most (n = 6) interventions documented the development of the subjects' social skillset.  Interventions were predominantly (n = 6) implemented by facilitators with musical expertise.  The authors concluded that the diverse and novel nature of the reviewed studies highlighted a need to expand and enhance research with this population.

Non-Invasive Brain Stimulation (Including Transcranial Direct Current Stimulation) for the Treatment of Dyslexia

Turker and Hartwigsen (2021) stated that non-invasive brain stimulation (NIBS) has gained increasing popularity as a modulatory tool for drawing causal inferences and exploring task-specific network interactions.  However, a comprehensive synthesis of reading-related NIBS studies is still missing.  These researchers filled this gap by synthesizing the results of 78 NIBS studies examining the causal involvement of brain regions for reading processing, and then linked these findings to a neurobiological model of reading.  The included studies provided evidence for a functional-anatomical double dissociation for phonology versus semantics during reading-related processes within left inferior frontal and parietal areas.  Furthermore, the posterior parietal cortex and the anterior temporal lobe were identified as critical regions for reading-related processes.  Overall, the results provided some evidence for a dual-stream neurobiological model of reading, in which a dorsal stream (left temporo-parietal and inferior frontal areas) processes unfamiliar words and pseudowords, and a ventral stream (left occipito-temporal and inferior frontal areas, with assistance from the angular gyrus and the anterior temporal lobe) processes known words.  However, individual differences in reading abilities and strategies, as well as differences in stimulation parameters, may impact the neuro-modulatory effects induced by NIBS.  The authors emphasized the need to examine task-specific network interactions in future studies by combining NIBS with neuroimaging.

Turker and Hartwigsen (2022) noted that NIBS can be used to actively and non-invasively modulate brain function.  Aside from inhibiting specific processes, NIBS may also enhance cognitive functions, which might be used for the prevention and intervention of learning disabilities such as dyslexia.  However, despite the growing interest in modulating learning abilities, a comprehensive, up-to-date review synthesizing NIBS studies with dyslexics is missing.  In a systematic review, these investigators examined the potential of NIBS as a therapeutic option in dyslexia.  The findings of the 15 included studies suggested that repeated sessions of reading training combined with different NIBS protocols may induce long-lasting improvements of reading performance in pediatric as well as adult dyslexics, opening promising avenues for future research.  In particular, the "classical" reading areas appeared to be most successfully modulated through NIBS, and facilitatory protocols could improve various reading-related sub-processes.  Moreover, these investigators emphasized the need to further examine the potential to modulate auditory cortex function as a pre-intervention and intervention approach for affected children (e.g., to avoid the development of auditory and phonological difficulties at the core of dyslexia).  The authors outlined how future studies may increase the understanding of the neurobiological basis of NIBS-induced improvements in dyslexia.

Salehinejad et al (2022) stated that among the target groups in child and adolescent psychiatry, transcranial direct current stimulation (tDCS) has been more employed in neurodevelopmental disorders specifically, attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and dyslexia.  In a systematic review, these investigators provided the latest update on published RCTs applying tDCS in these disorders for examining its safety and effectiveness.  Based on a pre-registered protocol and using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, a literature search identified 35 RCTs examining the effects of tDCS on children and adolescents with ADHD (n = 17), ASD (n = 11), and dyslexia (n = 7).  In ADHD, pre-frontal anodal tDCS was reported more effective compared to stimulation of the right inferior frontal gyrus.  Similarly in ASD, pre-frontal anodal tDCS was found effective for improving behavioral problems.  In dyslexia, stimulating temporo-parietal regions was the most common and effective protocol.  In ASD and dyslexia, all tDCS studies found an improvement in at least 1 of the outcome variables while 64.7 % of studies (11 of 17) in ADHD found a similar effect.  Approximately 88 % of all tDCS studies with a multi-session design in 3 disorders (16 of 18) reported a significant improvement in 1 or all outcome variables after the intervention.  Randomized, double-blind, controlled trials consisted of around 70.5 %, 36.3 %, and 57.1 % of tDCS studies in ADHD, ASD, and dyslexia, respectively.  tDCS was found safe with no reported serious side effects in 6,587 sessions conducted on 745 children and adolescents across 35 studies.  The authors concluded that tDCS was found safe and partially effective.  Moreover, these researchers stated that for evaluation of clinical utility, larger RCTs with a double-blind design and follow-up measurements are needed.  Titration studies that systematically examine different stimulation intensities, duration, and electrode placement are lacking.

Battisti et al (2022) noted that developmental Dyslexia (DD) significantly interferes with children's academic, personal, social, and emotional functioning; however, therapeutic options need to be further validated and tested in RCTs.  The use of tDCS has been gaining ground in recent years as a new therapeutic option for DD; yet, there are still questions on the most suitable tDCS protocol for young individuals with DD.  In a cross-over study, these researchers examined the effectiveness of a short and intensive tDCS protocol, including the long-term effects, as well as the influence of age and neuropsychological processes at baseline on reading improvements.  A total of 24 children and adolescents with DD were randomly assigned to receive active tDCS during the 1st slot and sham tDCS during the 2nd slot or vice-versa.  Five consecutive daily sessions of left anodal/right cathodal tDCS set at 1 mA for 20 mins were administered over the parieto-occipital regions.  Reading measures (text, high-frequency word, low- frequency word, and non-word lists) and neuropsychological measures (visual-spatial and verbal working memory, phoneme blending, and rapid automatized naming tasks) were collected before, immediately after, 1 week and 1 month later the treatment.  The findings showed that only the active tDCS condition improved non-word reading speed immediately after and 1 month later the end of the treatment compared with baseline.  Furthermore, the improvement in non-word reading speed was significantly correlated with age and with neuropsychological measures (verbal working memory and phoneme blending) at baseline but only in the active tDCS condition.  The authors concluded that this cross-over study contributed to enforce previous effects of tDCS, including long-term effects, on non-word reading speed and to understand the effect of age and neuropsychological processes on reading outcomes.  These findings showed that tDCS could be a low-cost and easy-to-implement therapeutic option with long-term effects for children and adolescents with DD.

These investigators stated that although the findings of non-invasive brain stimulation in DD are generally promising, RCTs are still few and had several methodological issues.  First, tDCS studies for the treatment of DD were characterized by small sample sizes with a maximum of 27 subjects and conducted mainly with between-subjects design.  Second, existing results were fundamentally heterogeneous probably due to high inter-subject variability.  Indeed, it has been widely recognized that the influence of stable factors (demographical, neuroanatomical, and genetical), or transient/contextual factors such as vigilance, hormonal activity, participant engagement or task predisposition could significantly produce heterogeneous results and alter the generalizability of findings observed in tDCS studies.  One possibility to overcome these limitations is to design studies with a larger number of participants and/or apply a cross-over design.  In fact, the cross-over study design was introduced in clinical research to obtain an effect estimate with the same level of accuracy as a between-subjects design, increasing statistical power even with a small number of participants, and suppressing the inter-subject variability.  Third, the medium- and long-term effectiveness of tDCS studies in DD has been poorly examined; and limited to studies in which stimulation was combined with reading training.

ChromaGen Lenses for Improvement of Learning Skills in Children with Dyslexia

In a prospective, single-center study, Alkhudairy and Al Shamlan (2022) examined the effectiveness of ChromaGen lenses and compared the pre- and post-intervention outcomes among individuals with non-ocular conditions such as dyslexia and Irlen syndrome and ocular conditions such as color vision deficiency (CVD) and cone-rod dystrophy (CRD).  This trial was carried out from 2016 to 2021 among cases (7 years or older) who were diagnosed with dyslexia, Irlen syndrome, CVD, or CRD.  Participants were given a short questionnaire to read, followed by asking direct questions regarding medical health history, ocular history, eyeglasses prescription, and a full orthoptics evaluation.  The main outcomes were the improvement in reading speed, reading accuracy, and visual stress.  A total of 156 patients were included in this study; 110 patients with dyslexia, 19 with Irlen syndrome, 16 with CVD, and 11 with CRD.  The findings showed that the reading speed and accuracy were improved in 96.34 % of patients with dyslexia and 78.9 % of patients with Irlen syndrome.  The use of ChromaGen lens was significantly associated with visual stress improvement in 89.8 % of patients (p = 0.02).  Photosensitivity was significantly improved after wearing the ChromaGen lenses in patients with CVD (87.5 %) and CRD (63.6 %).  The authors concluded that the findings of this study demonstrated a positive impact of ChromaGen lenses on reducing visual stress, including reading speed and accuracy, in patients with dyslexia and Irlen syndrome.  Photosensitivity improved in patients with Irlen syndrome and CRD.  Color vision was enhanced in patients with CVD.  Moreover, these researchers stated that further studies are needed to examine the predictors of improvement and evaluate the long-term effectiveness of ChromaGen lenses on daily activities and learning skills.

MoveR Training for Improvement in Visual Perceptual Skills in Dyslexic Children

Gibert et al (2022) compared the improvement in visual perceptual skills (by using the test of visual perceptual skills, TVPS) in children with dyslexia after 2 visual training types (a new immersive rehabilitation therapy called MoveR, and the classical vision therapy).  A total of 39 children with dyslexia were enrolled in the study.  They were divided into 2 groups (G1 and G2) matched in intelligence quotient (IQ), sex, and age.  Children in group G1 underwent MoveR training while children in group G2 underwent to visual training.  TVPS scores of 4 subtests were evaluated twice before and 6 months after the 2 different types of training (MoveR or classical visual therapy).  MoveR training is an immersive therapy to reinforce visual discrimination, visual attention, saccadic/vergence system and spatial orientation.  Visual therapy is based on training different types of eyes movements (horizontal, vertical, and oblique pursuits and saccades, convergence, and divergence movements), reading task, and some exercises for improving eyes-head coordination.  Each training type lasted 30 mins/day, 5 days/week, for 2 weeks.  Before training, the TVPS scores of the 4 subtests measured were statistically similar for both groups of children with dyslexia (G1 and G2).  After training, both group of children (G1 and G2) improved the TVPS score of the 4 subtests assessed; however, such improvement reached significance in G1 only.  The authors concluded that MoveR training could be a more useful tool than classical visual training to improve visual perceptual abilities in dyslexic children.  Moreover, these researchers stated that follow-up studies on a larger number of dyslexic children are needed to examine if such improvement would persist over time and its eventual implication in reading or other classroom's activities.  These investigators also noted that further imaging studies on a larger number of children are needed to better understand neurophysiological activities following MoveR and other training protocols.  Moreover, it could be interesting to test the benefits of the 2 programs on other cognitive abilities.

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References