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Phoria distribution for dyslexic ( white bars ) and non- dyslexic ( “ normals ” ; grey bars ) children at far and near distance. The median of dyslexics and non-dyslexics is also given
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There is a controversy as to whether dyslexic children present visuo-motor disabilities such as vergence and accommodative problems assessed with orthoptic tests. The purpose of this study is to re-examine this issue in a large population of children.
Extensive orthoptic evaluation was made in 57 dyslexic and 46 non-dyslexic ("normal") age-matched...
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... non-parametric Mann Whitney U test was used to test the existence of an overall difference between non-dyslexic and dyslexic children. Local comparison of frequency of certain values between non-dyslexic and dyslexic children was made with the Χ 2 test. Stereo-acuity The stereo-acuity threshold measured with the TNO test is similar in these two populations, as shown in Table 1. Indeed, the majority of children (99% of dyslexic and 100% of non-dyslexic children) show normal binocular vision (60 ′′ of arc or better at the TNO). Phoria Figure 1 shows the frequency distribution of phoria at far and near distance, respectively. At far distance the median value of phoria is zero for both non-dyslexic and dyslexic children ( P =0.19). At near distance, the median value of phoria is similar in the two populations ( − 2 pD for non-dyslexics and − 1.5 for dyslexics; P =0.19). Convergence capability The NPC (see Table 2) was significantly more remote in dyslexics than in non- dyslexics ( P <0.00001); non-dyslexics, with respect to dyslexics, more frequently had a value of NPC smaller than 6 cm: 72% versus 44% ( Χ 2 =8.01, P <0.004); in contrast, dyslexic children more frequently had a value of NPC between 7 – 10 cm than did non-dyslexic children: 36% versus 15% ( Χ 2 =5.73, P <0.01). Thus, the dyslexic group tended to have a more remote near point of convergence. Figure 2 shows the convergence capacity at far and near distance for the two populations, measured with the bar of prisms. The median value is 16 pD and 14 pD for non- dyslexics and dyslexics, respectively, at far distance ( P =0.12), and 20 pD for both non-dyslexics and dyslexics at near distance. Divergence capability Divergence measured with the bar of prisms is shown in Fig. 3; divergence amplitude is significantly different in the two populations for both distances ( P <0.005); at far, the median value is 6 pD and 4 pD in non-dyslexics and dyslexics, respectively, and 12 pD and 10 pD at near. Local comparisons also show several differences between the two populations; at far distance, for many of the dyslexics, divergence ability is limited to 4 pD: 28% versus 14% in non-dyslexics ( Χ 2 =4.32, P <0.03); non- dyslexics show powerful divergence ability, i.e. 8 pD, more frequently than dyslexics do (15% versus 6%, Χ 2 =7.08, P <0.008). Similarly, at near distance, local comparisons show several differences between non-dyslexics and dyslexics: divergence limited at 6 pD is more frequent for dyslexics, 9% versus 2% ( Χ 2 =3.74, P <0.05), while non- dyslexics show, more frequently than dyslexics do, ample divergence values, such as 16 pD, 4% versus 0% ( Χ 2 =4.96, P <0.02), or 18 pD, 9% versus 3% ( Χ 2 =4.72 P <0.02). Thus, divergence capacity is less powerful in the dyslexic group both at far and near distance. In summary, stereo-acuity capacity is normal in dyslexics. The most important findings of this study are: significantly more remote near point of convergence in dyslexics with respect to non-dyslexics, and significantly more limited divergence capacity both at far and near distance. Stereo-acuity The TNO stereo-acuity test used is one of the most objective tests based on colour red – green dissociation of random dot patterns. Our results clearly indicate that in this test non-dyslexic and dyslexic children are not different. Both populations have low normal thresholds of binocular disparity (60 ′′ of arc), which indicates a high degree of quality of binocular vision. Convergence In the present study we used two tests for measuring convergence. The first is the classic test of near point of convergence. In this simple test vergence is stimulated by many cues: disparity, blur and accommodation, proximal cues, eventually other monocular depth cues. In children with dyslexia the ability to converge the eyes appropriately in order to maintain single binocular vision was broken when the accommodative target — the letter — approached the child at 7 cm. The majority of non-dyslexic children can maintain single binocular vision at that distance and even closer. Divergence This is the most novel finding; indeed, reduced divergence capabilities in dyslexics at near vision (30 cm) were mentioned by Evans et al. [9]. Our findings at near distance are in agreement with that study, but the new information is that similar decreased capacity for divergence exists at far distance. The physiological significance of this finding will be discussed below. Divergence is considered, at least by some clinicians, as a passive mechanism of relaxation of convergence. When the divergence test is performed at near distance, one could consider that divergence is partially facilitated by the relaxation of convergence and accommodation. Thus, reduced capabilities of divergence at near distance could reflect abnormal relaxation of convergence and accommodation. However, when the divergence test is performed at far distance, the visual axes are already parallel, and accommodation and convergence are already relaxed. Yet, dyslexics show frequently reduced divergence capacity at far distance. Therefore, our study indicates that there is a divergence limitation per se in dyslexic children, which occurs in the absence of convergence and accommodation. The disparity convergence test shows no significant difference; on the other hand, divergence at near distance shows difference. Even though divergence at near can be assisted by normal convergence and accommodation, it is not entirely a convergence relaxation process; thus, the decreased divergence is also seen at near distance. Thus, the two results together, i.e. decreased divergence at near and at far distance reflect limitations of divergence per se, independently of convergence. Next, we will discuss physiological studies that demon- strated that divergence is based on distinct control both at the cortical and subcortical ...
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Citations
... Except for established ethnic differences and age differences [15,16,18,20,[75][76][77][78], most of the differences from standard values did not take refractive errors, visual demands, and technological developments into consideration [79][80][81]. Although it might not confer reading difficulties [82][83][84] when the accommodation range and the DBI break are both relatively high, overuse of near vision as well as excessive use of accommodation and cohesion, resulting in functional fatigue or rigidity, may lead to poor overall binocular visual performance (Fig. 2). Regardless of the study findings, it can be confirmed that the development of new Taiwanese binocular vision standard values should constitute a direction for future research. ...
Background:
Morgan and Scheiman's Optometric Extension Program (OEP) expected binocular vision findings have longstanding use in optometry. With technological advances, the demands and standards of binocular function have changed. This study aimed to investigate which binocular visual functions can effectively predict visual behavior performance.
Methods:
Participants aged 15-24 years were recruited from two colleges and two universities. After completing the CSMU-Visual Behavioral Performance questionnaire (CSMU-VBP, with four components: near work, visual perception, visual comfort, and whole-body balance), participants were divided into symptomatic and asymptomatic groups based on questionnaire findings (cutoff: < 12 vs. ≥ 12 symptoms). Then a 24-step binocular visual examination was undertaken. Data were analyzed with one-sample, Student's, and paired t-tests. Additionally, receiver operating characteristic analysis was used to determine the predictors of binocular visual function required for near work, visual perception, visual comfort, and body balance dimensions.
Results:
Among 308 participants, 43 (14%) and 265 (86%) were symptomatic and asymptomatic, respectively. Among the 46 participants with abnormal binocular vision, 36 (78%) reported that they had no obvious symptoms. The commonest dysfunctions were accommodative excess and convergence excess. Most of the binocular visual findings significantly diverged from traditional normal values: amplitude of accommodation, as well as base-in prism to break and recovery points at distance were higher than traditional normal values, whereas others were lower than traditional normal values. Total CSMU-VBP scores indicated that the asymptomatic and symptomatic groups had significant differences in DBO recovery (t = 2.334, p = 0.020) and BAF (t = 1.984, p = 0.048). Receiver operating characteristic curve analysis yielded the following binocular visual functional cutoff points: near work (DBO blur < 7, DBO recovery < 5.5), visual perception (MAF < 10.5, BAF < 10.25), visual comfort (DLP < - 2.25, DBI break > 11.5, NBI blur > 15, NBI break > 17.5, NBI recovery > 13, NPC < 5.75), and body balance (NFD_H > - 0.5, gradient AC/A [minus] > 2.25, NPC < 4.75).
Conclusions:
The mean values of binocular visual function among young Taiwanese adults were statistically different from traditional normative values. Further research is required to confirm whether these findings reflect impaired binocular vision or stringent criteria. Assessments of binocular visual function, especially binocular accommodation sensitivity, are crucial in routine optometric examination.
... 3 Only one study since 2001 has found a slightly more remote near point of convergence in a group of children with dyslexia than in a control group. 23 Other studies have found no significant difference in the near point of convergence of a group of dyslexic children compared with controls. 10 24 Of course, dyslexia may have many causes, and if convergence insufficiency is in fact a cause, but only one among many, it is unlikely to be detected in a group of dyslexic individuals unless the study is very large. ...
The main binocular vision and accommodative anomalies are considered in turn: strabismus, heterophoria, convergence insufficiency, binocular instability, accommodative insufficiency, and accommodative infacility. For each of these conditions, any associations with reading difficulties are reviewed, including their cause. The treatment of these conditions is discussed, also addressing the general question of when optometric factors need to be treated. The chapter closes with a summary table. It is concluded that binocular instability (fusional vergence dysfunction) is correlated with dyslexia, but is unlikely to be a major cause of the condition.
... Except for the proven ethnic differences and age differences[16,17,19,21,[65][66][67][68], most of the speculations that are related to the standard value did not take refractive errors, visual demand, and technological developments into consideration[69][70][71]. Although it might not be conferring reading di culty[72][73][74] when the accommodation range and the DBI break are both relatively high, overuse of near vision as well as the excessive use of accommodation and cohesion that results in functional fatigue or rigidity may lead to poor overall binocular visual performance. Regardless of the results of the study's analysis, it can be con rmed that the construction of a new Taiwanese native binocular vision standard value should constitute a direction for future research. ...
Purpose: Traditional normative values of binocular vision, known as Morgan’s & Scheiman’s and Optometry Extension Program(OEP) expected findings, have been used since long in clinical optometry. However, with technological advances, visual habits and visual demands have changed. Therefore, clinical assessment could examine the applicability of the established criteria in Taiwan.
Methods: Participants aged 15–24 years were recruited from three universities and colleges. After completing the Visual Behavioral Performance questionnaire with four components: near work, visual perception, visual comfort and balance of body, participants were separated into symptomatic or asymptomatic groups based on the results of the questionnaire survey. A 24-step binocular visual examination was undertaken. Data were analyzed with the one-sample t-test and an ROC curve to compare and establish normative values for Taiwanese young adults.
Results: Among the 308 healthy Taiwanese young adults, the prevalence of accommodation or vergence anomalies was 15% (46 participants). The commonest dysfunctions in this study were accommodative excess and convergence excess. Most of the binocular visual functions in this study showed significant difference from the traditional normative values: amplitude of accommodation, base-in prism to break and recovery points at distance were better than the traditional normative values, whereas others were worse. In addition, different visual tasks require different binocular visual functions, and the ROC curve was used to analyze the normative values of binocular visual functions required for near work, visual perception, visual comfort, and body balance.
Conclusion and Discussion: The mean values of binocular visual function in Taiwanese young adults were worse than that in the traditional normative values. With changing times, racial differences, and more tasks for visual needs, it is essential to establish binocular visual normative values for Taiwanese young adults.
... This interpretation is supported by the fact that children with dyslexia have normal eye movements when they perform tasks with control demands similar to reading but without the "cognitive" component (Hutzler et al., 2006). However, Kapoula, Bucci and their colleagues have published several studies on the neurophysiology of eye movements in dyslectic children, and they have found that dyslexics have poor binocular coordination of saccades, during a saccade the eyes show more variable conjugacy and after the saccade they have larger drift resulting in fixation instability (Bucci et al., 2008a;2008b;Jainta & Kapoula, 2011;Kapoula et al., 2007). Other studies have suggested that children with dyslexia have unstable binocular fixation (Castro et al., 2008;Vagge et al., 2015), and monocular instability has also been reported (Biscaldi et al., 1994;Fischer, 2012). ...
Imaging the tarsal plate and the meibomian glands (MG) grants new opportunities for ophthalmic practitioners who work in the field of the ocular surface and dry eye across the globe. The secretory role of MG plays a fundamental part in protecting the moisture in front of the eye surface by creating an active shield made of meibum (lipid) which prevents tear evaporation and causes dry eye. Evidence from the most popular Dry Eye Workshop reports (2007 and 2016) demonstrate that MG dysfunction is the first cause of evaporative dry eye which is also the most common cause of dry eye and ocular surface discomfort. Fortunately, during the last years, a plethora of new devices for MG observation, diagnosis and follow-up have been made available in the market. These devices range from invasive to minimally invasive, high to low-tech and from being expensive to low-cost. The objective of this mini-review is to condense the latest evidence in MG imaging by providing a narrative overview on the most common technologies plus some other newer aspects which might guide clinicians and researchers in the field of the ocular surface and dry eye.
... This interpretation is supported by the fact that children with dyslexia have normal eye movements when they perform tasks with control demands similar to reading but without the "cognitive" component (Hutzler et al., 2006). However, Kapoula, Bucci and their colleagues have published several studies on the neurophysiology of eye movements in dyslectic children, and they have found that dyslexics have poor binocular coordination of saccades, during a saccade the eyes show more variable conjugacy and after the saccade they have larger drift resulting in fixation instability (Bucci et al., 2008a;2008b;Jainta & Kapoula, 2011;Kapoula et al., 2007). Other studies have suggested that children with dyslexia have unstable binocular fixation (Castro et al., 2008;Vagge et al., 2015), and monocular instability has also been reported (Biscaldi et al., 1994;Fischer, 2012). ...
After more than a year of blockade due to the Covid-19 pandemic, it was finally possible to return to the events in the presence. The 26th National Conference of the Italian Optometric Association (SOPTI) was held in Bologna on October 10–11, 2021. The theme of the conference was “Good practice in Optometry and Contact Lenses”, with the accent on two topics: the optometric management of the patient in old age and the progression of myopia. Four keynote speakers were invited during the conference: Prof. Rigmor C. Baraas from the University of South-Eastern Norway in Kongsberg, Prof. David B. Elliot from the University of Bradford, Dr. Fabrizio Zeri from the University of Milano Bicocca and the IACLE President, Prof. Phil Morgan, from the University of Manchester. The abstracts from accepted posters and free papers are presented here.
... This interpretation is supported by the fact that children with dyslexia have normal eye movements when they perform tasks with control demands similar to reading but without the "cognitive" component (Hutzler et al., 2006). However, Kapoula, Bucci and their colleagues have published several studies on the neurophysiology of eye movements in dyslectic children, and they have found that dyslexics have poor binocular coordination of saccades, during a saccade the eyes show more variable conjugacy and after the saccade they have larger drift resulting in fixation instability (Bucci et al., 2008a;2008b;Jainta & Kapoula, 2011;Kapoula et al., 2007). Other studies have suggested that children with dyslexia have unstable binocular fixation (Castro et al., 2008;Vagge et al., 2015), and monocular instability has also been reported (Biscaldi et al., 1994;Fischer, 2012). ...
... This interpretation is supported by the fact that children with dyslexia have normal eye movements when they perform tasks with control demands similar to reading but without the "cognitive" component (Hutzler et al., 2006). However, Kapoula, Bucci and their colleagues have published several studies on the neurophysiology of eye movements in dyslectic children, and they have found that dyslexics have poor binocular coordination of saccades, during a saccade the eyes show more variable conjugacy and after the saccade they have larger drift resulting in fixation instability (Bucci et al., 2008a;2008b;Jainta & Kapoula, 2011;Kapoula et al., 2007). Other studies have suggested that children with dyslexia have unstable binocular fixation (Castro et al., 2008;Vagge et al., 2015), and monocular instability has also been reported (Biscaldi et al., 1994;Fischer, 2012). ...
Developmental dyslexia affects around 5-15% of the population and has a heterogeneous aetiology. Optometric disorders are more prevalent in dyslexic populations but the relationship be- tween eye movement control and dyslexia is not well established. In this study, we investigated whether children with dyslexia show saccadic or fixation deficits and whether these deficits are related to deficits in visual acuity and/or accommodation. Thirty-four children with and without dyslexia were recruited for the project. All participants had an optometric examination and performed a saccade and fixation experiment. We used two eye movement paradigms: the step and the gap task. Eye movements were recorded by an infrared eye-tracker and saccade and fixation parameters were analysed separately. Saccadic latencies, premature saccades, and directional errors were similar between children with dyslexia and typically developing children. In contrast, fixations were significantly less stable in the dyslexic group. Neither saccades nor fixations were associated with deficits in accommodation or visual acuity. Children with dyslexia showed no difficulties in saccadic performance, but their fixation stability was reduced compared to the control group. The reduced fixation stability can be explained by general deficits in the cognitive processes that underpin eye movement control, that have also been found in other neuro-developmental disorders.
... For instance, in the dyslexic population, eye movement abnormalities in vergence have been reported using clinical subjective tests since 1988 and in binocular coordination of saccades to LED targets [1][2][3][4][5]. Most recently, Ward and Kapoula conducted a complete study of large saccades and vergence eye movements in depth using LED targets [6]. They reported specific abnormalities not only in the velocity profile of both saccade and vergence eye movements but also in certain binocular coordination aspects such as increased disconjugate post-saccadic drifts and saccade disconjugacy. ...
... Given that the predictive value of eye movements during reading has been shown to be dependent on the text, there is a real need to compare ML analysis on non-reading tests. The present study uses the data sets from two studies by Ward and Kapoula: the first testing large saccades and vergence with LED targets, and the second testing reading in two texts of varying difficulty to evaluate the capacity of eye movements to predict dyslexia [6,11]. Eye movements from all tasks were analyzed with the AIDEAL software to produce measurements of multiple physiologically valid spatiotemporal descriptors of eye movements (e.g., latency, amplitude, duration, peak, average velocity, drifts, etc.) We applied several ML models (linear and non-linear) and evaluated their differential accuracy and capacity to predict dyslexia, as well as the reading speed. ...
... Given that the data used for the ML analysis is taken from published studies, please see Ward and Kapoula for full details regarding methods and materials [6,11]. In brief, eye movements were recorded during reading and non-reading tasks in 46 dyslexic adolescents (18 female, 28 male; mean age 15.52, SD 2.45) and 41 non-dyslexic adolescents (20 female, 21 male; mean age 14.78 +/− 2.44) recruited from schools in Paris. ...
There is evidence that abnormalities in eye movements exist during reading in dyslexic individuals. A few recent studies applied Machine Learning (ML) classifiers to such eye movement data to predict dyslexia. A general problem with these studies is that eye movement data sets are limited to reading saccades and fixations that are confounded by reading difficulty, e.g., it is unclear whether abnormalities are the consequence or the cause of reading difficulty. Recently, Ward and Kapoula used LED targets (with the REMOBI & AIDEAL method) to demonstrate abnormalities of large saccades and vergence eye movements in depth demonstrating intrinsic eye movement problems independent from reading in dyslexia. In another study, binocular eye movements were studied while reading two texts: one using the “Alouette” text, which has no meaning and requires word decoding, the other using a meaningful text. It was found the Alouette text exacerbates eye movement abnormalities in dyslexics. In this paper, we more precisely quantify the quality of such eye movement descriptors for dyslexia detection. We use the descriptors produced in the four different setups as input to multiple classifiers and compare their generalization performances. Our results demonstrate that eye movement data from the Alouette test predicts dyslexia with an accuracy of 81.25%; similarly, we were able to predict dyslexia with an accuracy of 81.25% when using data from saccades to LED targets on the Remobi device and 77.3% when using vergence movements to LED targets. Noticeably, eye movement data from the meaningful text produced the lowest accuracy (70.2%). In a subsequent analysis, ML algorithms were applied to predict reading speed based on eye movement descriptors extracted from the meaningful reading, then from Remobi saccade and vergence tests. Remobi vergence eye movement descriptors can predict reading speed even better than eye movement descriptors from the meaningful reading test.
... Among neurodevelopmental motor disorders, DCD is characterized by deficits in the acquisition and execution of coordinated motor skills, and is manifested by clumsiness and slowness or inaccuracy in the performance of motor skills that cause interference with activities of daily living [1]. All these neurodevelopmental conditions have been associated with different alterations of ocular movements with potential impact on learning and reading activities [4][5][6][7][8], leading in some cases to the establishment of incorrect causal relationships [9], even though reading difficulties are not relevant for the diagnostic criteria of DCD or ADHD [1]. Furthermore, there are even doubts about the most adequate criteria for diagnosing oculomotor alterations in this type of disorders [9]. ...
... Dyslexia was present in 15 children, ADHD in 7 children, and a diagnosis of the motor disorder DCD was made in the remaining 6 children. According to previous studies, these children were expected to have oculomotor abnormalities in most cases [4][5][6][7][8][9]. The same exclusion criteria as those used in the other two groups were considered. ...
... Besides oculomotor alterations, some studies have reported a relatively high prevalence of accommodative and binocular anomalies in children with specific learning disorders [8,10,14,32,46]. As happened with oculomotor deficits, accommodative and binocular alterations have also been suggested to be a potential etiologic factor in some neurodevelopmental disorders. ...
A prospective, non-randomized comparative study was conducted to compare the distribution of oculomotor and visual alterations in children with neurodevelopmental disorders and healthy children without such disorders. Sixty-nine children (aged 6–13 years) were enrolled and divided into three groups: a control group (CG) of 23 healthy children; a group of 18 healthy children with oculomotor abnormalities (OAG); and a group of 28 children with a neurodevelopmental disorder (NDDG), with 15 cases of dyslexia, 7 cases of developmental coordination disorder (DCD) and 6 cases of attention deficit/hyperactivity disorder (ADHD). Significantly worse near stereopsis was found in NDDG compared with CG (p < 0.001) and OAG (p = 0.001). Likewise, a significantly lower amplitude of accommodation was found in NDDG compared with CG in both the right (p = 0.001) and left eyes (p < 0.001). No statistically significant differences between groups were found in the measurement of near and distance phoria (p ≥ 0.557), near point of convergence (p = 0.700) and fusional vergences (p ≥ 0.059). Significantly impaired oculomotor test scores were found in NDDG compared with CG (p < 0.001), with no significant differences between OAG and NDDG (p ≥ 0.063). The comparison between the three types of neurodevelopmental disorders included revealed the presence of a significantly lower amplitude of accommodation in children with DCD compared with dyslexics. Furthermore, less exophoria at near was present in children with dyslexia compared with children with ADHD (p = 0.018) and DCD (p = 0.054). In conclusion, children with dyslexia, ADHD and DCD show an altered oculomotor pattern and a more reduced amplitude of accommodation, not always compatible with the diagnostic criteria of an accommodative insufficiency. Accommodative and binocular vision problems are not always present in these children and cannot be considered an etiologic factor.
... More recently, eye movement abnormalities in dyslexic adolescents have been demonstrated using more objective measurements, some resulting in increased latencies of both vergence and saccadic movements 11,17,20,21 . There has even been evidence to show that vergence training may improve reading in dyslexic adolescents (increased number of words read per minute), indicating there is a basis of vergence abnormality to their primary deficit 22 . ...
... Could phoria be playing a role in dyslexics' vergence velocity profiles? A previous study conducted by the lab with clinical orthoptic evaluation found no statistical difference in phoria between dyslexic and non-dyslexic populations; although heterophoria was more prevalent in the dyslexic population, it was only seen when measured at far distance 20 . Unfortunately, in the present study, phoria was not measured given our previous finding and the subjectivity of the test. ...
Previous studies suggest vergence and saccade abnormalities in dyslexic adolescents. However, these studies are mainly clinically based and do not provide objective measurements of eye movements, but rather subjectively evaluate vergence using haplosopic conditions in which the two eyes are dissociated (via polarizers, prisms, or intermittent spectacles). Other studies have identified deficits with binocular coordination during reading in dyslexics. Yet, there are few studies that provide objective measurements of eye movements in the dyslexic population to help provide more information regarding if these deficits could be due to an intrinsic motor problem or if they are the consequence of poor reading. 47 dyslexic adolescents (18 female, 29 male; mean age 15.5) and 44 non-dyslexic adolescents (22 female, 22 male; mean age 14.8) wore a head-based eye tracker (PupilCore, Pupil Labs, Berlin) which recorded wide angle saccade and vergence eye movements at 200 Hz. Tests were run using the REMOBI device, which produced a saccade or vergence audiovisual target. Analysis of eye movements was performed with lab-developed software, AIDEAL. The results showed statistically significant abnormalities in vergence and saccades. In vergence, dyslexics displayed a reduced amplitude of the visually driven portion of convergence and a longer duration in the initial phase of divergence. In saccades, dyslexic adolescents demonstrated slower saccades in both directions. They also had an increased disconjugate drift in the first 80 or 160 ms following saccades to the right, suggesting poor binocular coordination. For both vergence and saccades, the peak velocity and time to peak velocity was higher and earlier, respectively, in non-dyslexics compared to dyslexics; yet the average velocity of both movements was lower in dyslexics. Thus, these results indicate peculiar velocity profiles in dyslexics, particularly a slow deceleration phase in both vergence and saccades. The study provides an objective method to diagnose vergence and saccade abnormalities while viewing targets in the real three-dimensional space in a dyslexic population. Vergence abnormalities are demonstrated to be a problem in dyslexics, occurring independently from reading. We hypothesize these disconjugate drifts following saccades are the result of slow vergence capacity. Rehabilitation programs, such as those using REMOBI, should aim to target these deficits in vergence velocity, as this has been shown to improve binocular control.
