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Reading processes and visual or surface «dyslexia» – part 2

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Lexical or whole-word reading

Competent reading essentially involves the whole-word or lexical process of reading which ensures fluent reading and a “direct” access to meaning. It recognizes the shape of the word and immediately find its sound correspondence in memory (or phonological), the meaning of the word being evoked, which is the ultimate goal of reading.

The whole-word process (or eidetic = photographic), both more automatic and faster, can even bypass the phonological pathway, which is more controlled and slower. Most of the time, the expert reader would not need to use his phonological knowledge to recognize written words. The observation of a double dissociation between visual and phonological dyslexia in patients with brain damage is an argument in favor of the neuropsychological existence of the two independent procedures for the recognition of written words (Coltheart, Masterson, Byng, Prior & Riddoch, 1983; Funnell, 1983; Shelton & Weinrich, 1997). Numerous studies supporting these models have also emphasized the optional phonological code while reading (Peereman, 1991, for a review).

Coltheart M, Masterson J, Byng S, Prior M, Riddoch J. Surface dyslexia. Q J Exp Psychol A. 1983 Aug;35(Pt 3):469-95.

Funnell E. Phonological processes in reading: new evidence from acquired dyslexia. Br J Psychol. 1983 May;74 (Pt 2):159-80.                     

Weinrich M, Shelton JR, McCall D, Cox DM. Generalization from single sentence to multisentence production in severely aphasic patients. Brain Lang. 1997 Jun 15;58(2):327-52.

Peereman R. Phonological assembly in reading: lexical contribution leads to violation of graphophonological rules. Mem Cognit. 1991 Nov;19(6):568-78.

When the child becomes able to recognize a word as a unit, he gradually builds his orthographic lexicon. The operation of this lexicon is not yet fully known, but it seems to be like a dictionary which exists in our brain, allowing rapid identification (the faster the more familiar word) and immediate access to meaning.

This procedure then develops to become more and efficient as reading becomes more competent. Ultimately, the adult reader would only use the “photographic” procedure, which is obviously much faster than going through words syllable by syllable (which remains necessary when we must read for example, new or meaningless words or of a foreign language).


Imagine a child who reads the following sentence:

The locomotive arrives at the station



(or syllable by syllable)



In the first case, the child immediately recognizes the words and understands what he reads. In the second case, the child does not read words but syllables one by one. Difficult to quickly understand what is read.


Surface dyslexia

Surface dyslexia, in its pure form, is characterized by a selective impairment of reading irregular words while reading regular words and pseudo-words is relatively preserved. This selective difficulty reading irregular words translates a dysfunctionnal lexical reading procedure.

These children do not present associated disorders of oral language and have good capabilities in short term verbal and workong memory and have good phonological awareness. They also have difficulties in visual processing that make comparing sequences of letters or identify targets among others.

It is said that pure forms of surface dyslexia are relatively rare in clinical practice. But I can assure you that in my optometric practice, these children are much more numerous than the statistics show.

Visuo-attentional dyslexia

There is also, according to some authors, another form of dyslexia, called “visual-attentional” where the child has a good memory of the spelling of words and is able to transcribe sounds into words. For cons, the type of errors encountered in this disorder is reversals in groups of letters, omissions, additions, approximate reformulations, skippng lines while they read.  line breaks. The child may confuse letters and words with others closely resembling it. It would be a disorder affecting necessary attention for an effcient reading activity.

(In : http://www.ac-grenoble.fr/ia73/spip/IMG/pdf/dys_apedys.pdf)

These children also have oculomotor (eye movement) and visual discrimination problems, difficulties in visual attention, difficulties in copying material from a book or the blackboard.

It is difficult to conceive a child who has a serious visuo-attentional problem would not show a form of surface dyslexia. There is certainly a very close relationship between the two since both can prevent the establishment of a proper orthographic lexicon. They may also be different manifestations of the same problem called “visual dyslexia”. This close relationship between visual and attentional problems is reinforced by the significant progress in reading and spelling seen in a child with surface dyslexia following a trainign program focused on visual processing capabilities (Launay and Valdois , 1999)

Valdois S, Launay L. Évaluation et rééducation cognitives des dyslexies développementales: illustration à partir d’une étude de cas.  In : La rééducation neuropsychologie : Études de cas. AZOUVI P, PERRIER D, VAN DER LINDEN M (eds). Marseille, Solcoll, 1999 : 95-116).

 Visual-perceptual skills essential to insure adequate whole-word reading

It is probably unnecessary to say that the best readers are those who read in a whole-word fashion, this  method of reading is fast and understanding is also much better. But what is the action to take if a child uses no or has a poor orthographic lexicon? We must ensure that the related visual and perceptual skills are adequate. Otherwise, visual training will be needed to improve these skills.

What are the skills that have a close relationship with the development of orthographic lexicon? First, eye movements: reading requires a constant movement of the eyes along a line of text, which is done by a series of short jumps (saccades) interspersed with longer breaks during which takes place all intake of visual information. These jumps between fixations are very short, about one-thirtieth of a second. Saccades take approximately 250 to 300ms. Saccades are also an index of visual attention. We have tests that evaluate the speed, accuracy and fluency of reading. Eye movement problems hamper efficient learning and reading quality (failure to follow the text, loss of place, jump words or lines, etc.). For reading to be effective, eye movements must be flexible, fast and accurate.

Then visual attention and concentration allow the child to remain focused and attentive to every detail of what we see and as long as necessary. Attention and concentration are a preqequisite to good visual discrimination. In addition, visual attention is the link between perception (making information available) and cognition (use this information). It ensures maximum reception all the information from our visual environment. Visual concentration promotes maximum use of working memory to collect, store, retrieve and process the relevant information. It facilitates the work and especially the intellectual performance.

Short-term and sequential visual memories allow the child to recognize an item after a brief exposure, or to recall items in the same order and in the same sequence. For example, remembering the order of letters in a word or words in a sentence with a quicker understanding of what is read. Children who show difficulties in visual sequential memory may have difficulties copying information from the board or a book, to learn to read mulriple words or sentences and remember what they read. They may also have difficulties in creating their orthographic lexicon, which affects fluency and reading comprehension.

Visualization or mental imagery is the ability to create images of a word, a sentence or a paragraph in our head (our mental picture). This ensures good understanding of what is read and allows a better organization of information, making it easier to retain and build an efficient orthographic lexicon. This perceptual skill is also essential for mental arithmetic and spelling of words. If a child reads a story without being able to mentally see the scene described in the text, then this will influence contextual

In summary, the eyes must move effectively to ensure high quality of visual information, and the child must be able to remain attentive and focused on what he reads. Visual memory will also allow to recognize the same words in a text. Many children can not build a orthographic lexicon because they can not even recognize a word they just read and read again a few lines later. Visualization allows the child to “juggle with words” in his head. And finally, it is practicing reading every day that ensures efficiency in reading. More often we see the same words, the faster they will be included in the orthographic lexicon.


According to scientific research, three basic skills (among others) will thus directly influence reading performance in children: visual memory, visual attention and visualization. The best readers are capable of recognizing whole words easily (eidetic, global or whole-word reading). This accelerates visual decoding, requires less energy and promotes better understanding. Reading phonologically (syllable by syllable) slows down the reading process and does not guarantee an adequate understanding of a text. The best readers need not phonological awareness to read and can recognize most words without having to dissect them. That is why we have developed a particular portion of our vision therapy to enhance these perceptual abilities. We try to develop better whole-word reading to improve reading efficiency and comprehension.

Reading processes and visual or surface «dyslexia» – part 1

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“True“dyslexia is seemingly a “neurological” dysfunction (of course, we read with our brain, not just the eyes!) marked by the inability of the brain centers to efficiently decode print or phonetically make the connection between written symbols and their appropriate sounds. The connotation of the word “neurological” can be confusing: this word is too easily understood or related to a nervous system disease. Dyslexia may be caused by a nervous system dysfonction, but surely not a disease!

The origin of this problem, yet ardently debated in the literature, is probably multi-causal. It is unfortunate that the researchers are constantly looking at only a small aspect of dyslexia in their studies. We also know that not all children who have difficulty reading, however, suffer from phonological processing. Although the symptoms are similar, they may also have visual and perceptual problems that interfere with adequate learning, not just a deficit-based language, as some would have us believe…

Margaret Livingstone, et al, from the Department of Neurobiology, Harvard Medical School and the Dyslexia Research Laboratory, Beth Israel Hospital in Boston reports that poor visual processing plays a significant role in a large majority of children who struggle to read:   “Several perceptual studies have suggested that dyslexic subjects process visual information more slowly than normal subjects.  Such visual abnormalities were reported to be found in more than 75% of the reading-disabled children tested.”

Livingstone MS, Rosen GD, Drislane FW, et al. Physiological and anatomical evidence for a magnocellular defect in developmental dyslexia. Proc Natl Acad Sci USA 1991; 88:7943-7.

Moreover, all children with learning difficulties in primary school are not dyslexic, and vice versa, a child may be dyslexic without it being prolonged failure (especially if dyslexia is mild and if it can be compensated by the development of other skills intact).

Essentially, there is also a problem in the clinical definition of dyslexia. Everyone has their own definition and tests used in the diagnosis of such a condition do not always lead to a clear diagnosis… This imprecision in diagnosis can also certainly explain the variability in prevalence rates reported in the literature (this rate may actually increase from 4% (Yule and Rutter, 1973) to 20% (Shaywitz, 1996)).

Yule W, Rutter M, Berger M, Thompson J. Over- and under-achievement in reading: distribution in the general population. Br J Educ Psychol. 1974 Feb;44(1):1-12. 

Shaywitz SE. Dyslexia. Sci Am. 1996 Nov;275(5):98-104.

A child in early primary school may have some difficulty learning to read, this situation is common and there is no question of going overboard and put a label of  “dyslexia” for all these children.

Decoding process of reading: the dual-route model

The dual-route model is very frequently used as a reference model for decoding during reading. This model postulates the existence of two procedures involved in both reading and writing.


Dual-route reading process

From : http://www.cognisciences.com: Outil de Dépistage des Dyslexies – Odedys2 – 2009

Phonological process

The phonological process is characterized by a sequential analytical processing or syllabic of a word or pseudo-word (invented word). It involves a system of rules for grapheme (a letter or two, sometimes three) – phoneme (sound related) explicitly learned in school.

The word “camel” when processed through this system will be segmented into graphemes <CA – MEL>, then each grapheme will be assigned to a phoneme which is most frequently associated in the language This allows to generate the sequence of the word.

Only the phonological process allows the processing of new words (words not previously learned or “pseudo-words” which are words invented for the purposes of experiment, for example: famsled, posvent or rolted).

Insofar as the treatment of new words is dedicated to this system, lists of pseudo-words are systematically tested for reading and dictation for children with difficulties, to test the integrity of the phonological process. Good performance in reading invented words indicates that the phonological process is operational, poor performance involves an inadequacy of this pathway.

It is known that the analytical (phonological) route plays a major role in early learning as it is chronologically the first. If we conceive that in adults both channels are relatively autonomous, it seems unlikely that these two pathways are also distinct in children who are learning to read.

Whole-word or eidetic process

The lexical procedure (or whole-word process) performs simultaneous processing of all the elements of the word. All units which compose the word are processed in parallel, leading to the activation of the orthographic lexicon stored in the brain and learned previously. The child sees the word and understands it immediately.

In reading, and after some visual processing, the representation of the word as a whole is activated in our orthographic lexicon (the “dictionary within our head”) and gives a very rapid access to the sound structure (phonology) corresponding to this word and its meaning. No need to decode the word syllable by syllable.

The way this lexicon functions is not yet fully known, but it seems to be like a dictionary to which we would refer for each word read, according to a “photographic” procedure, allowing rapid identification (the faster the more familiar is the word) and immediate access to meaning.

Each of the two procedures for reading (or writing) is implemented specifically for the treatment of certain types of words: the lexical route or process can only deal with words already learned and whose representations are available within the orthographic lexicon and its phonological correspondence. It is needed when reading or writing irregular words that are not pronounced the way they are written (for example, rough, soared, laugh). Irregular words that can only be handled by the lexical route is used in the evaluation of children with learning disabilities. Lists of irregular words are proposed or presented to test the integrity of the lexical route: a good performance when reading these words shows that the lexical procedure is operational; poor performance in reading irregular words compared to reading regular words or pseudo-words suggests a failure of the lexical procedure.

(Part 2 in next blog)

New study: eye movement problems in dyslexic children

The authors say that studies comparing binocular eye movements during reading and visual search in dyslexic children are inexistent. In the present study they examined ocular motor characteristics in dyslexic children versus two groups of non dyslexic children with chronological/reading age-matched. Binocular eye movements were recorded by an infrared system (mobileEBTH, e(ye)BRAIN) in twelve dyslexic children (mean age 11 years old) and a group of 9 chronological age-matched and 10 reading age-matched non dyslexic children. Two visual tasks were used: text reading and visual search. Infrared devices permit recording eye movements on a graph for further analysis.

Independently of the task, the ocular motor behavior in dyslexic children is similar to those reported in reading age-matched non dyslexic children: many and longer fixations as well as poor quality of binocular coordination during and after the saccades.

Note: If the age reading scores are similar in both groups of children, and one of the group includes dyslexic children, we could assume that the group of children called “normal readers” have not scored very high on the reading task (like the dyslexics). That would explain the behavior of eye movements (ocular motor) of the two groups is similarly ineffective. Difficult to understand?

According to the authors, for the two groups of dyslexic and non dyslexic children, the two tasks (reading and visual search) produced similar effects in terms of fixations and in terms of binocular coordination. It is believed that reduced visual and attentional span (or “visuo-attentional window”) which limits the number of letters that can be processed simultaneously, could have a similar impact on reading and visual search, due to the visuo- attentional demand similar in both tasks. Most likely, at least for these two groups of children for whom reading skills are not yet well structured, reading and visual search has important requirements in the spheres of vision-perception, attention and space processing. 

In contrast, chronological age-matched non dyslexic children showed a small number of fixations and short duration of fixations in reading task with respect to visual search task; furthermore their saccades were well yoked in both tasks. The atypical eye movement’s patterns observed in dyslexic children suggest a deficiency in the visual attentional processing as well as an immaturity of the ocular motor saccade and vergence systems interaction.

Recording of eye movements during reading (first column) and visual search (second column). We observe that the number and duration of fixations of the dominant right eye for a dyslexic child (11 years old), a non-dyslexic child 9 years old and a 11 years old non-dyslexic. The dyslexic child shows more fixations and regressions (backward movements). In the second case, the eye movements of the non-dyslexic child of 9 years old are more efficient but still lack precision if we compare the movements of the 11 years old non-dyslexic child.

Source: Bucci MP, Nassibi N, Gerard C-L, Bui-Quoc E, Seassau M (2012) Immaturity of the Oculomotor Saccade and Vergence Interaction in Dyslexic Children: Evidence from a Reading and Visual Search Study. PLoS ONE 7(3): e33458.

 Note: please click on «Reference» in the upper right corner of the page to get more information about eye movements in dyslexic children.

ADHD diagnosis: research

ADHD Is Over-Diagnosed, Experts Say

Source: ScienceDaily, 2012

What experts and the public have already long suspected is now supported by representative data collected by researchers at Ruhr-Universität Bochum (RUB) and University of Basel: ADHD, attention deficit hyperactivity disorder, is over-diagnosed. The study showed that child and adolescent psychotherapists and psychiatrists tend to give a diagnosis based on heuristics, unclear rules of thumb, rather than adhering to recognized diagnostic criteria. Boys in particular are substantially more often misdiagnosed compared to girls.

These are the most important results of a study conducted by Prof. Dr. Silvia Schneider and Prof. Dr. Jürgen Margraf (both from RUB) and Dr. Katrin Bruchmüller (University of Basel) as reported in the periodical Journal of Consulting and Clinical Psychology.

Daniel has ADHD, Danielle does not 

The researchers surveyed altogether 1,000 child and adolescent psychotherapists and psychiatrists across Germany. 473 participated in the study. They received one of four available case vignettes, and were asked to give a diagnoses and a recommendation for therapy. In three out of the four case vignettes, the described symptoms and circumstances did not fulfil ADHD criteria. Only one of the cases fulfilled ADHD criteria based strictly on the valid diagnostic criteria. In addition, the gender of the child was included as a variable resulting in eight different case vignettes. As the result, when comparing two identical cases with a different gender, the difference was clear: Leon has ADHD, Lea doesn’t.

The “prototype” makes the difference

Many child and adolescent psychotherapists and psychiatrists seem to proceed heuristically and base their decisions on prototypical symptoms. The prototype is male and shows symptoms such as motoric restlessness, lack of concentration and impulsiveness. In connection with the gender of the patient, these symptoms lead to different diagnoses. A boy with such symptoms, even he does not fulfil the complete set of diagnostic criteria, will receive a diagnosis for ADHD, whereas a girl will not. Also the therapist’s gender plays a role in the diagnostic: male therapists give substantially more frequently a diagnosis for ADHD than their female counterparts.

Diagnostic inflation, more medication, higher daily doses

In the past decades the diagnoses ADHD have become almost inflationary. Between 1989 and 2001, the number of diagnoses in German clinical practise increased by 381 percent. The costs for ADHD medication, such as for the performance-enhancer methylphenidate (Ritalin), have grown 9 times between 1993 and 2003. The German health insurance company, Techniker, reports an increase of 30 percent in methylphenidate prescriptions for its clients between the ages of 6 and 18. Similarly, the daily dosage has increased by 10 percent on average.

Remarkable lack of research

Considering these statistics, there is a remarkable lack of research in the diagnostic of ADHD. “In spite of the strong public interest, only very few empirical studies have addressed this issue,” Prof. Schneider and Dr. Bruchmüller point out. While in the 70s and 80s a “certain upswing” of studies on the frequency and reasons for misdiagnoses could be observed, current research hardly examines the phenomena. The current study shows that in order to avoid a misdiagnosis of ADHD and premature treatment, it is crucial for therapists not to rely on their intuition, instead to strictly adhere to defined, established diagnostic criteria. This is best possible with the help of standardized diagnostic instruments, such as diagnostic interviews.

Vision and ADHD (2)

Rouse et al., in 2009, also conducted a study to determine whether children with symptomatic convergence insufficiency, without the presence of parent-reported Attention Deficit Hyperactivity Disorder (ADHD) had higher scores using a questionnaire on school behavior, the ABS Academic Behavior Survey.

The group of optometrists developed a questionnaire called the Academic Behavior Index (ABS). The Academic Behavior Survey is a 6-item survey that evaluates parent concern about school performance and the parents’ perceptions of the frequency of problem behaviors that their child may exhibit when reading or performing schoolwork (such as: difficulty completing work, avoidance, and inattention). The survey was administered to the parents of 221 children 9-17 years old with symptomatic convergence insufficiency and to 49 children with normal vision.

The results of this study showed that 15% of the convergence insufficiency group and children with normal vision were classified as ADHD by parental report. The total ABS score for the symptomatic convergence insufficiency with parent-report of ADHD group was significantly higher than the symptomatic convergence insufficiency with no parent-report of ADHD group. The authors concluded that both children at risk for ADHD or related learning problems should have a comprehensive vision evaluation to assess the presence of convergence insufficiency as a contributing factor.

The ABS questionnaire:

  • How often does your child have difficulty completing assignments at school?
  • How often does your child have difficulty completing homework?
  • How often does your child avoid or say he/she does not want to do tasks that require reading or close work?
  • How often does your child fail to give attention to details or make careless mistakes in schoolwork or homework?
  • How often does your child appear inattentive or easily distracted during reading or close work?
  • How often do you worry about your child’s school performance?

The symptoms frequently reported in convergence insufficiency such as loss of concentration when reading or reading slowly are similar to behaviors associated with ADHD (inattentive type), such as, failure to complete assignments and trouble concentrating in class.

The same team of optometrists in 2012, sought to determine whether treatment of symptomatic convergence insufficiency had an effect on the scores of the questionnaire Academic Behavior Survey (ABS), used previously.

The ABS was administered at baseline and after 12 weeks of treatment to the parents of 218 children aged 9 to 17 years with symptomatic CI, who were enrolled in the Convergence Insufficiency Treatment Trial and randomized into (1) home-based pencil push-ups; (2) home-based computer vergence/accommodative therapy and pencil push-ups; (3) office-based vergence/accommodative therapy with home reinforcement; and (4) office-based placebo therapy with home reinforcement. Participants were classified as successful (n = 42), improved (n = 60), or non-responder (n = 116) at the completion of 12 weeks of treatment using a composite measure of the all visual tests.

A successful or improved outcome after the convergence insufficiency treatment was associated with a reduction in the frequency of adverse academic behaviors and parental concern associated with reading and school work as reported by parents.

ADHD and Vision

Children with undetected vision problems can exhibit symptoms similar to ADD.  Studies show that approximately 20% of school-aged children suffer from eye teaming or focusing deficits which make remaining on task for long periods of time difficult.  Like those with ADD, children with vision-based learning problems are highly distractible, have short attention spans, make careless errors, fail to complete assignments, and are often fidgety and off task.  However, their inability to remain on task is caused by the discomfort of using their eyes for long periods of time at close ranges, not true deficits in attention.  Unfortunately, parents and teachers are not trained to recognize the difference and these children are often misdiagnosed.

These children are often looking around the room, getting a drink, going to the bathroom, staring out the window, or talking to their neighbors.  They’re taking “vision breaks,” although they don’t realize that’s what they’re doing. Children with eye teaming problems have always seen this way, and most are not aware that their close-up vision is not normal.  Few report eye strain or blurred or double print; all they know is that they cannot continue with their seat work one more moment.  As the day progresses, they become increasingly fatigued and frustrated

Any child who is suspected of having ADD should have a complete eye exam by a pediatric specialist in children’s vision to determine if poor visual processing is a factor in the child’s behavior.  Unlike ADD  is diagnosed by a subjective checklist, objective clinical measures and tests can be run to determine for certain if the child has a learning-related vision problem which is making it difficult for him to remain on task.

25% of Children May Have a Learning-Related Vision Problem (source: www.covd.org)

Research supports what optometrists have known for some time — a significant percentage of children with learning disabilities have some type of vision problem.  One study found that 13% of children between nine and thirteen years of age suffer from moderate to marked convergence insufficiency, and as many as one in four, or 25%, of school age children may have a vision problem that can affect learning. If we now consider visual-perceptual problems, nearly 60 % of children with learning problems will sow these types of problems.

ADHD questionnaire

The DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, fourth edition) contains the Diagnostic Criteria for diagnosing Attention Deficit (Hyperactivity) Disorder:


The child:

  1. Often fails to give close attention to details or makes careless mistakes in schoolwork, work, or other activities 
  2. Often has difficulty sustaining attention in tasks or play activities
  3.  Often does not seem to listen when spoken to directly
  4. Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behaviour or failure of comprehension)
  5. Often has difficulty organizing tasks and activities
  6. Often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework)
  7.  Often loses things necessary for tasks or activities at school or at home (e.g. toys, pencils, books, assignments)
  8. Is often easily distracted by extraneous stimuli
  9. Is often forgetful in daily activities

It is interesting to note that five behaviors (outlined above) out of the 9 present in the DSM-IV may also be due to visual-perceptual problems!


What is important to consider in a visual and perceptual examination in presence of a child who suffers from an attention deficit disorder?

We must clearly identify the following visual and perceptual aspects that modulate visual attention and concentration:

  • Eye movements
  • Functional problems such as problems focusing, eye alignment and convergence problems (excess or insufficiency)
  • Visual attention skills
  • Visual discrimination skills
  • Visual memory skills


• Borsting E, Rouse M, Chu R. Measuring ADHD behaviors in children with symptomatic accommodative dysfunction or convergence insufficiency: a preliminary study. Optometry 2005;76:588-92.

• Granet DB, Gomi CF, Ventura R, Miller-Scholte A. The relationship between convergence insufficiency and ADHD. Strabismus 2005;13:163-68.

• Gronlund MA, Aring E, Landgren M, Hellstrom A. Visual function and ocular features in children and adolescents with attention deficit hyperactivity disorder, with and without treatment with stimulants. Eye 2007;21:494-502.

• Rouse M, Borsting E, Mitchell GL, Kulp MT, Scheiman M, Amster D, Coulter R, Fecho G, Gallaway M.Academic behaviors in children with convergence insufficiency with and without parent-reported ADHD. CITT Study Group. Optom Vis Sci. 2009 Oct;86(10):1169-77.

• Borsting E, Mitchell GL, Kulp MT, Scheiman M, Amster DM, Cotter S, Coulter RA, Fecho G, Gallaway MF, Granet D, Hertle R, Rodena J, Yamada T; CITT Study Group. Improvement in academic behaviors after successful treatment of convergence insufficiency. Optom Vis Sci. 2012 Jan;89(1):12-8.

Vision and ADHD (1)

Research: possible link between convergence insufficiency and attention deficit disorder (ADHD), the answer to everything?


Convergence is the inward movement that both eyes make when, for example, we are approaching an object close to the eyes. Both eyes should be looking at the same location in space.

Convergence insufficiency is a difficulty for the eyes to move more and more near the nose. When convergence is insufficient, the child may suffer from eyestrain or even double vision, depending on the extent of the problem.

In fact, the convergence test is rather simple to administer. Ask the child to look at a target (small penlight or a pencil, for example) which is located at eye level. Approach the target to the eyes, which will be  converging until either 1) the child reports double vision or 2) you can observe that one eye loses fixation and moves outwards. Note the distance at which this occurs. This portion of the test is called the “break point of convergence.” The normal distance is about 5 cm (2 inches). Closer still, the eyes can not converge anymore.

The second part of the test is to measure the “recovery point” of convergence. Once the break point is reached, you simply move the target slowly away from the eyes until you see that both eyes are now fixating the target. The normal distance from the point of recovery is about 10 cm (4 inches) (see figure below). Of course, doing the test requires some practice.

We note the test as follows:

Convergence test: 8 cm / 20 cm (break point / recovery point)

Possible link between convergence and ADHD

An article published in the scientific literature in 2005 has created a stir that still persists. We know that the diagnosis of ADD or ADHD is mainly done by questionnaire and that there are no objective tests to make this diagnosis. But in 2005, a research has shown a possible link between convergence insufficiency and attention deficit hyperactivity disorder (ADHD). The beginning of a new era?

A potential relationship between convergence insufficiency and attention deficit hyperactivity disorder (ADHD) has been uncovered by researchers at the University of California, San Diego. “This is the first report on the potential connection of these two disorders,” Dr. David B. Granet, ophthalmologist [UCSD Shiley Eye Center].

The study “showed that children with convergence insufficiency are three times more likely to be diagnosed with ADHD than children without the disorder.” We will come back to this study and others…

Scientific studies

Now back to the study by Dr. Granet and his team. This study argues that children being evaluated for attention deficit hyperactivity disorder (ADHD) often have an eye exam as part of their evaluation. The symptoms of convergence insufficiency (CI) can make it difficult for a student to concentrate on extended reading and overlap with those of ADHD. Surprising statement from an ophthalmologist when we know that these doctors are rarely concerned with such problems.

A retrospective review of 266 patients with CI presenting to an academic pediatric ophthalmology practice was performed. All patients included were diagnosed with CI by one author and then evaluated for ADHD diagnosis. A computerized review was also performed looking at the converse incidence of CI in patients carrying the diagnosis of ADHD.

Twenty-six patients (9.8%) were diagnosed with ADHD at some time in their clinical course. Of the patients with ADHD and convergence insufficiency, the review of computer records showed a 15.9% incidence of CI in the ADHD population. It would therefore seem to be a three-fold greater incidence of ADHD in patients with convergence insufficiency when compared with the incidence of ADHD in the general US population (1.8-3.3%). The authors also noted a three-fold greater incidence for this convergence problem in the population with ADHD. This may simply represent an association and not be a causal link.

But just before Dr. Granet’s article, a team of optometrists (Borsting et coll., 2005) publihed a research on the same subject a a few months before.

Borsting et al. identified accommodative (focusing) and convergence insufficiency problems in relation to other learning difficulties such as attention deficit hyperactivity disorder (ADHD). The purpose of this study was to evaluate the frequency of ADHD behaviors in school-aged children with symptomatic accommodative dysfunction or convergence insufficiency.

24 children from 8 to 15 years of age with symptomatic accommodative dysfunction or convergence insufficiency were included in this study. One parent of each child completed the Conners Parent Rating Scale-Revised Short Form (CPRS-R:S). The children’s scores on the CPRS-R:S were compared with the normative sample.

Regarding the Conners questionnaire, and more specifically the S, cognitive problem/inattention, hyperactivity, and ADHD indexes were significantly different from normative values (p < or = .001 for all tests).

The results from this preliminary study suggest that school-aged children with symptomatic accommodative dysfunction or convergence insufficiency have a higher frequency of behaviors related to school performance and attention as measured by the Conners questionnaire.

Gronlund et al. in 2007 studied various aspects of visual function in children with attention deficit hyperactivity disorder (ADD / ADHD) and establish whether treatment with stimulants is reflected in functioning of the visual system.

In all, 83% of children had normal visual acuity without treatment, and 90% with the use of stimulants. A problem with eye alignment (phoria) was found in 29% without treatment, and 27% with stimulants. A stereoscopic vision problem (three-dimensional vision) was found in 26% without stimulants, and 27% with stimulants. Abnormal convergence (> 6 cm or no convergence) was noted in 24% without treatment and 17% with treatment. Signs of visual-perceptual problems were found in 21% of all children. Children with AD/HD had a high frequency of visual findings, which were not significantly improved with stimulants.

Visual attention and reading problems

Tackling Dyslexia Before Kids Learn to Read

From: ScienceDaily (Apr. 5, 2012) —

For children with «dyslexia», the trouble begins even before they start reading and for reasons that don’t necessarily reflect other language skills. That’s according to a report published online in Current Biology, a Cell Press publication, that for the first time reveals a causal connection between early problems with visual attention and a later diagnosis of dyslexia.

“Visual attention deficits are surprisingly way more predictive of future reading disorders than are language abilities at the prereading stage,” said Andrea Facoetti of the University of Padua in Italy.

The researchers argue that the discovery not only closes a long-lasting debate on the causes of dyslexia but also opens the way to a new approach for early identification and interventions for the 10 percent of children for whom reading is extremely difficult.

The researchers studied Italian-speaking children for a period of three years, from the time they were prereading kindergarteners until they entered second grade. Facoetti’s team, including Sandro Franceschini, Simone Gori, Milena Ruffino, and Katia Pedrolli, assessed prereaders for visual spatial attention — the ability to filter relevant versus irrelevant information — through tests that asked them to pick out specific symbols amid distractions. The children also took tests on syllable identification, verbal short-term memory, and rapid color naming, followed over the next two years by measures of reading.

Those test results showed that kids who initially had trouble with visual attention were also the ones to later struggle in reading.

“This is a radical change to the theoretical framework explaining dyslexia,” Facoetti said. “It forces us to rewrite what is known about the disorder and to change rehabilitation treatments in order to reduce its impact.”

The author says that simple visual-attention tasks should improve the early identification of children at risk for dyslexia. “Because recent studies show that specific prereading programs can improve reading abilities, children at risk for dyslexia could be treated with preventive remediation programs of visual spatial attention before they learn to read.”