Oculomotor Dysfunctions in Non-Reading Tasks in Children with Developmental Dyslexia: Saccadic and Optokinetic Findings

Oculomotor Dysfunctions in Non-Reading Tasks in Children with Developmental Dyslexia: Saccadic and Optokinetic Findings | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Oculomotor Dysfunctions in Non-Reading Tasks in Children with Developmental Dyslexia: Saccadic and Optokinetic Findings Melikşah Safa Üçok, Mustafa Dinçer, Ceren Karaçaylı, Esra Güngör Bağlıcakoğlu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6526788/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract Specific learning disorder (SLD) is a neurodevelopmental disorder characterized by difficulties in reading, writing and math skills. Saccadic eye movements play a critical role in fluent reading and visual scanning. 40 children with dyslexia and 40 healthy controls were included in this study according to DSM-5 criteria, since children with dyslexia have reading fluency disorders and saccadic eye movements are necessary for fluent reading. Psychiatric evaluations and structured clinical interviews were conducted by an experienced child and adolescent psychiatrist. Saccadic eye movements (saccadic velocity, accuracy and latency) were recorded using a videonystagmography (VNG) system and compared between the two groups. Results showed that children with dyslexia exhibited significantly lower saccadic velocity (307.5°/s vs. 453.5°/s, p < 0.001) and saccadic accuracy (71.5% vs. 98.5%, p < 0.001) and significantly longer saccadic latency (260.0 ms vs. 131.5 ms, p < 0.001). Optokinetic responses in the right eye were significantly less in the SLD group (p = 0.028), whereas no significant difference was observed in the left eye responses (p = 0.067). These findings suggest that children with dyslexia have significant oculomotor dysfunction independent of the act of reading. This may contribute to reading difficulties and impaired visual information processing, and oculomotor assessment in dyslexia may be a useful tool in the development of etiologic diagnosis and interventions. Psychiatry Otorhinolaryngology Psychology Dyslexia Eye movement Eye tracking Learning disabilities Reading disability Oculomotor Saccades INTRODUCTION Developmental dyslexia (DD) is a specific learning disorder (SLD) defined as an individual's inability to develop reading or writing skills adequately despite adequate intellectual capacity and appropriate education. Although studies on the prevalence of DD may vary due to reasons such as the population studied, screening and diagnostic methods, and the orthographic structure of the language, the prevalence between the ages of 6–13 is reported to be around 7.1% (Yang et al., 2022 ). The difficulties experienced by individuals with DD not only hinder their academic performance. They also affect their cognitive and psychological development throughout life, leading to long-term consequences (Adi et al., 2024 ; Piko & Dudok, 2023 ; Snowling et al., 2020 ). In order to minimize these long-term consequences, diagnosis and intervention at the earliest possible age becomes crucial to significantly change the educational trajectory and self-esteem of affected individuals (Virlet et al., 2024 ). Although traditional methods used in the diagnosis of DD are very important in terms of diagnosis, they can create problems by potentially disadvantaging some individuals due to subjective interpretation of the results and sometimes not taking cultural and linguistic diversity into account. Therefore, there is an increasing need for early diagnosis with objective methods and individualized interventions for etiology (Bucci, 2021 ; Caldani et al., 2020 ; Dalvand et al., 2023 ; Grigorenko et al., 2020 ; Nguyen et al., 2024 ; Virlet et al., 2024 ) Theories about the etiology of DD have been debated for many years (Stein, 2023 ). The biggest problem in DD is the ability to separate words into their component sounds and to associate letters and sounds with phonological awareness. Although there is strong scientific evidence that dyslexia is explained by the phonological coding deficit theory, this theory alone cannot explain all cases (Chi et al., 2025 ; Stein, 2019 ). One of the alternative approaches, the magnocellular theory, argues that a defect in the magnocellular system in the timing of visual events and the control of eye movements during reading may lead to difficulties with visual motion sensitivity and binocular stability, resulting in abnormal eye movements in individuals with dyslexia. Deficits in the perception of fast visual information may affect eye movements in individuals with DD (Coenen et al., 2024 ). A poor strategy in visual information processing has been suggested to be the cause of the abnormal eye movements observed in children with DD. On the contrary, the hypothesis of impairment of the visual system is still controversial in terms of causality, as differences in eye movements may also affect the perception of visual information (Ceple et al., 2025 ; Eden et al., 1994 ; Granet, 2011 ; Ibrahimi et al., 2024 ; Jafarlou et al., 2021 ; Stella & Engelhardt, 2021 ; Vagge et al., 2015 ; Vikesdal et al., 2021 ). Individuals with DD show deficits not only in phoneme processing but also in oculomotor skills (Nguyen et al., 2024 ). Some studies have reported visual and oculomotor differences in children with DD, suggesting that there may be dysfunction in the oculomotor system as well as deficits in the magnocellular system (Coenen et al., 2024 ; Demir et al., 2023 ; Ölçek et al., 2023 ). In this context, it has been shown that oculomotor patterns in DD differ from normal not only during the reading task but also in the pursuit of sequentially moving light targets (Jafarlou et al., 2021 ). Therefore, eye movement control, which is known to be impaired in DD, should be considered independently of phonological awareness (Bucci, 2021 ) . During reading, the eyes need to fixate on the words, perform correct saccadic movements and focus and align both eyes. The oculomotor system, which is among the most critical structures in this process, enables the individual to track visual targets, fixate on words and quickly switch to different targets when necessary. During the functioning of this system, eye movements need to be regulated in an integrated manner with inputs from both the cerebellar and vestibular systems. In particular, the cerebellum regulates the accuracy and timing of saccadic movements, while the vestibular system maintains visual stability by counterbalancing head and body movements (Doettl et al., 2015 ; Doettl & McCaslin, 2018 ; Tobener et al., 2024 ). These neuroanatomical systems work together to provide the function of three basic eye movements: fixation, saccadic movements and smooth pursuit. Early studies suggested that children with DD exhibit irregular eye movements outside of reading tasks and that a general oculomotor dysfunction should be considered due to motor coordination deficits and gaze instability (Pavlidis, 1981 ). In addition to impairments in motor automation and timing in some individuals with DD, it has been suggested that the likelihood of vestibular dysfunction is higher in these children (Natrayan & Chauhan, 2025 ). In oculomotor dysfunction, more attentional resources are required to overcome the coordination imbalance, which may reduce the resources needed for cognitive tasks. It may also cause cognitive resources to be used for motor control instead of attention, negatively affecting reading performance. Studies show that deficits especially in horizontal eye tracking movements, affect reading fluency and accuracy (Fella et al., 2023 ; Rodríguez et al., 2025 ). DD have been observed to exhibit longer and more numerous fixations, shorter saccades and more frequent backward eye movements (Bonifacci et al., 2023 ). Oculomotor dysfunction has been reported as a significant factor in children with poor reading skills even in the absence of a formal diagnosis of a learning disorder (Ibrahimi et al., 2024 ). Although it has been suggested that abnormal eye movements in DDs are often a consequence of reading difficulties and not the cause, the absence of impairments in non-verbal targets is expected, but this is not the case, suggesting that there may be a general deficit in oculomotor skills (Vikesdal et al., 2021 ) . Recently, studies on the use of eye tracking technology in terms of objective diagnostic approach have been increasing (Ashburn et al., 2020 ; Ashidiqi et al., 2023 ; Bilbao et al., 2024 ; Bonifacci et al., 2023 ; Caldani et al., 2020 ; Ceple et al., 2025 ; Coenen et al., 2024 ; El Hmimdi et al., 2021 ; Fella et al, 2023 ; Ibrahimi et al., 2024 ; Jafarlou et al., 2021 ; Jothi Prabha & Bhargavi, 2020 ; Macambira et al., 2022 ; Nerušil et al., 2021 ; Protasevica et al., 2024 ; Rodríguez et al, 2025 ; Stella & Engelhardt, 2021 ; Svaricek et al., 2025 ; Toki, 2024 ; Vaitheeshwari et al., 2024 ; Vikesdal et al., 2021 ; Virlet et al., 2024 ; Wang et al., 2022 ). Advances in eye-tracking technology have enabled more objective assessment of oculomotor parameters such as fixation stability, saccadic latency and tracking accuracy in individuals with SLD. High-resolution systems such as videonystagmography (VNG) can facilitate the investigation of saccadic eye movement abnormalities, contributing to a better understanding of their relationship with reading difficulties and identifying new biomarkers for early diagnosis and intervention (Dalvand et al., 2023 ; Jafarlou et al., 2021 ; Macambira et al., 2022 ). The methodologies used to understand the relationship between SLD and eye movements vary considerably. It is not clear whether changes in eye movements in individuals with DD are solely related to the reading process or are the result of a general neurobiological dysfunction. Therefore, in order to understand the normal functioning of eye movements during reading, it is necessary to examine how saccadic movements function in nonreading tasks as well The current study aims to evaluate saccadic eye movement abnormalities in children diagnosed with DD compared to a healthy control group. In particular, we will investigate whether parameters such as saccadic velocity, accuracy and latency can serve as potential diagnostic markers for children with DD using a non-reading task. Accordingly, eye movement data obtained with VNG of dyslectic and typically developing children will be compared. Only a single test protocol was used in order to keep motivation high, to reduce the involvement of higher-order cognitive processes associated with reading in eye movement performance, and to reduce distractor effects. METHODS Participants This case-control study was conducted between November 2022 and April 2023 after the approval of the Clinical Research Ethics Committee of Gülhane Training and Research Hospital (Approval Date: October 12, 2022; Decision No: 2022/135). The study included 40 children between the ages of 8–12 years diagnosed with DD from the Child and Adolescent Psychiatry outpatient clinic of Gülhane Training and Research Hospital and 40 age-gender matched healthy controls. The diagnosis of DD was made by a child psychiatrist according to DSM-5 criteria and confirmed by a child and adolescent psychiatrist. Children in the control group had no history of psychiatric or neurologic disorders. Inclusion criteria were meeting the age limit, having normal cognitive capacity and meeting the diagnostic criteria for DD in the patient group, no concurrent psychiatric or neurological disorders, no condition affecting cognitive function, no history of epilepsy or head trauma, and no use of medications that could affect oculomotor function. To ensure the absence of additional psychiatric conditions, both groups underwent psychiatric evaluation using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version, DSM-5 -Turkish Adaptation (Ünal et al., 2019 ). Experimental Procedure Assessments were performed in the hospital audiology laboratory using a videonystagmography (VNG) system (ICS Otometrics, Taastrup, Denmark) that incorporates high-resolution infrared cameras within a head-mounted goggle system to capture binocular eye movements in real time. Prior to testing, the system was calibrated using a laser dot fixation array to ensure precise gaze tracking. Participants were seated 120 cm from a stimulus display bar in a dimly lit room to minimize external visual distractions. The device operated at a sampling rate of 100 Hz, while saccades were detected using a velocity threshold of 40°/s and an acceleration threshold of 800°/s². Gain settings were kept at 150 µV/10°. Blinks were automatically detected and removed from the recording by an artifact rejection algorithm based on pupil closure. VNG is one of the laboratory tests that evaluate the vestibular system. However, VNG cannot evaluate the entire vestibular system; it only provides information about the vestibulo-ocular reflex. The test battery consists of oculomotor tests, gaze stabilization tests and positional tests. The oculomotor tests (saccade, pursuit and optokinetic tests) provide information, especially about central vestibular system function. Saccadic Eye Movement Test Procedure For calibration, the participant was asked to look 30° to the right, left, above and below the center line of the light bar with the VNG goggles on, while keeping the head still. A 20-second recording was taken for each position. In addition, a spontaneous nystagmus test was performed in complete darkness with eyes open to detect abnormal involuntary eye movements. Participants were then presented with a visual target that randomly appeared in horizontal positions within ± 15°-20° and had to make rapid saccadic movements to locate the target. Stimulus intervals were randomized between 3–4 seconds to avoid anticipatory responses. The total recording time was one minute, during which time important saccadic parameters such as Saccadic Velocity (°/s), Saccadic Accuracy (%) and Saccadic Latency (ms) were obtained. In addition, the participant was asked to count the lights at fixed intervals on the light bar with his/her eyes and this process was recorded for 20 seconds. The calculation of asymmetry between the participant's right and left tracking traces was included. Optokinetic responses (OKR) were analyzed separately for the right and left eyes to examine potential asymmetries. Data Processing and Analysis Recorded saccadic eye movements were processed using onboard ICS analysis software. Trials affected by excessive noise or blink artifacts were automatically removed prior to statistical analysis. All data analyses were performed using IBM SPSS Statistics (Version 26, IBM Corp., Armonk, NY, USA). Descriptive statistics were reported as mean ± standard deviation (SD), median (M), interquartile range (IQR) and minimum-maximum values. Depending on the data distribution, group comparisons were made using parametric (independent samples t-test) or nonparametric (Mann-Whitney U test) methods. Chi-square test was used for categorical variables. The overall statistical significance level was set at p < 0.05. RESULTS Descriptive Statistics A total of 80 children, 40 children diagnosed with DD and 40 healthy controls, participated in the study. As presented in Table 1, the ages of the participants ranged between 8 and 12 years. The mean age of the DD group was 9.5 ± 1.4 years, while the mean age of the control group was 9.9 ± 1.4 years, and there was no statistically significant difference between the groups (p = 0.276). The proportion of female participants was 60.0% (n = 24) in the DD group and 62.5% (n = 25) in the control group, and no significant difference was found between the groups (p > 0.999). Eye Movement Findings Children with DD exhibited significantly lower saccadic velocity compared to the control group (M = 307.5°/s, SD = 47.5 vs. M = 453.5°/s, SD = 85.0; p < 0.001). Similarly, saccadic accuracy was reduced in the SLD group (M = 71.5%, SD = 13.0) compared to the control group (M = 98.5%, SD = 8.5; p < 0.001). In addition, saccadic latency was significantly prolonged in children with DD (M = 260.0 ms, SD = 104.0) compared to the control group (M = 131.5 ms, SD = 30.0; p < 0.001). In terms of OKR, right eye responses were significantly lower in the DD group compared to the control group (p = 0.028), but no significant difference was observed in left eye responses (p = 0.067). However, the percentage difference in OKR between the right and left eyes was significantly higher in the DD group compared to the control group (p = 0.049) (Table-2). DISCUSSION The findings of this study show that children with DD exhibit marked oculomotor differences even in simple visual tasks that do not involve reading. The DD group showed significantly slower saccadic eye movement velocity, lower saccadic accuracy and prolonged saccadic latency compared to the control group. In addition, OKR were also abnormal in DD; especially the right eye OKR response was attenuated, whereas there was no significant difference in the left eye. These findings suggest that there are differences in eye movement functions in DD even in a task independent of reading, suggesting that dyslexia may not only be a phonological disorder but also a comprehensive neurodevelopmental difference affecting visual-motor systems. Saccadic Eye Movements: Velocity, Accuracy and Latency Previous research has reported that individuals with DD have lower saccade velocity and accuracy rate and longer saccade latency than normal readers in various eye movement tasks (Demir et al., 2023; Görker et al., 2017; Jafarlou et al., 2021; Ölçek et al., 2023; Tiadi et al., 2014). It has also been suggested that while saccadic latency shortens with age in typical children, there may be a slowdown in this developmental trajectory in those with DD (Ceple et al., 2025; Miladinović et al., 2022; Sinno et al., 2020). The longer time requirement for target orientation suggests slow processing in the brain's relevant networks (Pensiero et al., 2013). The findings of a study that observed that DD exhibited different saccadic eye movements in pursuit of moving targets compared to the control group suggest that there may be a deficit in processing moving visual stimuli in dyslexia (Jafarlou et al., 2021). In our study, healthy children were largely accurate in getting saccades to the target point, whereas those with DD were less accurate. This suggests that people with DD have difficulty in precisely controlling their eye movements (Jafarlou et al., 2021; Macambira et al., 2022) . Such inaccurate saccadic behaviors could be an explanation for the regression movements and prolonged fixations also observed during reading. Indeed, it has been consistently reported across different languages and orthographies that individuals with dyslexia exhibit shorter amplitude saccades (not reaching the target) and frequent regression movements during reading (Pavlidis, 1981; Seassau et al., 2014; Trauzettel-Klosinski et al., 2010; Vagge et al., 2015; Vikesdal et al., 2021; WU et al., 2018). Optokinetic Responses (OKR) Asymmetry and Vestibular Contribution Another remarkable finding of our study was the asymmetry in the OKR. Children with DD exhibited significantly poorer OKR in the right eye, whereas it was almost normal in the left eye. This difference suggests that there may be an imbalance in the connectivity between the hemispheres in visual processing in DD. It has been suggested that structural and functional abnormalities are more pronounced in the left hemisphere compared to the right in DD (Xia et al., 2016) . Under normal conditions, both eyes and both hemispheres contribute symmetrically to the tracking of visual movements; however, our study shows that in DD, a sufficiently strong response to moving stimuli tracked by the right visual field is not produced. This may be a reflection of left hemisphere dysfunction. As the left hemisphere is dominant in language processing, it also has a certain dominant role in visuomotor integration (Stein, 2023). In the case of a developmental deficit in the left hemisphere, the right-sided visual field may be affected, to relatively poor OKR. On the other hand, Salem et al. reported that there was no difference between dyslexic and control children in terms of OKR speed acquisition (Salem et al., 2022). Nevertheless, there is a need for further investigation of OKR in DD, which is a subject that has been little studied in the literature (Demir et al., 2023). If this asymmetry is consistently demonstrated in research, new light will be shed on the hitherto relatively neglected issues of binocular visual processing and hemispheric lateralization in the neurobiology of dyslexia. The OKR is an eye movement response that results from the close interaction of visual-motor integration and the vestibular system. In a moving visual environment, it works together with the vestibulo-ocular reflex (VOR) to stabilize the image on the retina. The fact that we observe a weak OKR in the right eye in children with dyslexia may also indicate an integration problem originating from the vestibular system. Recent research has drawn attention to the role of vestibulo-ocular integration in learning disorders such as dyslexia (Bilbao et al, 2024; Demir et al., 2023; Macambira et al., 2022; Nas Özütemiz et al., 2025; Natrayan & Chauhan, 2025; Ölçek et al., 2023; Picciotti et al., 2024). In particular, it has been suggested that the coordination between the vestibular system and eye movements may be poor in children with dyslexia and this may contribute to both visual attention and postural balance problems. Although our finding does not directly measure vestibular function, it indirectly supports this view. The asymmetry in OKR may be due to deficits in the integration of vestibular inputs with oculomotor control. Recently, in studies evaluating vestibular system functions in children with DD, it was reported that these children performed poorly in vestubulo-ocular integration tests compared to the control group (Demir et al., 2023; Ölçek et al., 2023). The vestibular system facilitates line tracking during reading through the VOR, which allows the eyes to be stabilized despite head and body movements. If there is a weakness in vestibulo-ocular integration in dyslexia, this may both disrupt the stability of eye movements and increase problems such as line skipping and misalignment during reading. Future electrophysiologic or imaging-based studies that more directly examine the relationship between the vestibular system and oculomotor control in individuals with dyslexia will help to elucidate the underlying mechanisms of our findings. Some studies have not found significant differences between DD groups and controls in terms of eye movements (Ceple et al., 2025; Vinuela-Navarro et al., 2017). Such contradictory results may be due to the inclusion of subjects who have not been diagnosed with "dyslexia" in groups with reading difficulties, such as poor readers for various reasons, or the heterogeneous composition of the subjects, masking the true dyslexia-specific eye movement differences. Moreover, they may have included comorbidities such as attention deficit hyperactivity disorder (ADHD), anxiety disorder and other psychopathologies without fully differentiating them. In our study, we tried to obtain a homogeneous sample with a definite diagnosis as much as possible by using the DD group who had significant reading difficulties to the extent that they presented to a child-adolescent psychiatrist and whose diagnosis was clearly established afterwards and whose comorbid conditions were excluded. In this way, we believe that we were able to observe more clearly the saccadic differences that can only be attributed to dyslexia. Although our findings are consistent with many previous studies, we think that the different results may be due to the methodology or sample used in the studies. Theoretical Framework The classic explanation of DD focuses on a specific deficit in the areas of phonological awareness and language processing. According to this approach, linguistic encoding problems are at the root of reading difficulties and other symptoms such as eye movement abnormalities are considered as secondary manifestations. However, our findings provide evidence that eye movement control in children with DD can be impaired independently of phonological processes. Our use of a non-reading task showed that children with dyslexia exhibit abnormal eye movement profiles even without any reading. In the literature some theoretical approaches have suggested that audiovisual sensory anomalies in dyslexia may be a separate component from phonological impairment (Stein, 2023). In particular, by emphasizing that impairment in the dorsal visual flow pathways in dyslexia is a factor in itself, he argued that reading disability is not only a phonological but also a visual-motor learning problem. This view is not shared by all researchers (Blythe et al., 2018). Eye movement abnormalities in DD, at least some of them, should not be treated as a consequence of phonological deficits, but rather as a direct indication of a neurodevelopmental difference. Of course, even if the main difficulty in dyslexia is phonological language processing (Chi et al., 2025), a one-dimensional explanation is not sufficient to cover all cases. Therefore, the assessment of eye movements in nonreading non-cognitive tasks offers a valuable approach to understand the interplay between phonological and visual theories (Jafarlou et al., 2021; Vikesdal et al., 2021). Our results show that DD has an independent visuomotor component in addition to phonological deficit, suggesting the need to update theoretical models accordingly. Our results are largely consistent with magnocellular theory. Magnocellular theory suggests that individuals with dyslexia have difficulty processing visual stimuli, especially moving visual stimuli, and that this negatively affects the control of eye movements during reading (Stein, 2019). In our study, we found a slowing and delay in saccades in response to moving light targets in DD, suggesting that processing of fast visual motion information is disrupted. Such a reduction in visual motion sensitivity is precisely the outcome predicted by magnocellular/dorsal pathway dysfunction. The concept of oculomotor dysfunction is actually a symptom description and is discussed as a fundamental cause or consequence in dyslexia (Bucci et al., 2012; Ibrahimi et al., 2024; Salem et al., 2022). Virlet et al. (2024) emphasized that posture, balance and coordination skills should also be targeted in interventions for children with dyslexia, drawing attention to the sensorimotor and proprioceptive basis of reading difficulties (Virlet et al., 2024) . The cerebellar theory, another explanation of dyslexia, suggests that reading difficulties are caused by problems in the automaticity acquisition phase and that mild motor-coordination disorders in the cerebellum are reflected in language processing. According to this theory, even small-scale motor skills such as precise timing of eye movements may be impaired in individuals with dyslexia (Nicolson et al., 2001) . In our study, differences were found in oculomotor functions in DD compared to controls. The origin of this dysfunction may be a dysfunction in the magnocellular system, cerebellar timing mechanisms or attention systems. Importantly, our findings suggest that DD is not only a phonological disorder but may also have sensorimotor aspects. Although the diagnosis in our study was based on the phonological theory, the results of our study strongly overlap with the oculomotor deviations, magnocellular visual pathway theory, confirm the concept of oculomotor dysfunction, and provide limited and indirect support for components such as cerebellar theory, vestibular system and general sensory integration disorders. This multifaceted picture is in line with the multiple deficit model suggesting that dyslexia cannot be reduced to a single cause and is the result of atypical development of multiple nervous systems (Bonifacci et al., 2023). Indeed, current views emphasize that in addition to phonological processing difficulties, disruptions in a number of cognitive processes such as visual perception, attention, auditory memory, etc. may together constitute developmental learning disabilities (Odegard et al., 2024) . There are some limitations that should be taken into consideration when interpreting the findings of our study. First, our sample size is relatively small and limited to applicants from a single center. Therefore, the generalizability of our findings may be limited. Second, participants' visual acuity and eye health were not assessed by a detailed clinical examination. Although the families were informed that the children had no known visual problems before inclusion in the study and the possibility of severe visual impairment was considered low since they were school-going children, a standard ophthalmologic examination was not performed. Although it has been reported in the literature that there is generally no significant difference in the basic visual functioning of children with dyslexia (Ibrahimi et al., 2024), we did not directly control for this factor in our study. Third, our study has a cross-sectional design. This means that we cannot definitively answer the question of whether eye movement differences are a cause or a consequence of dyslexia. They could be an early disorder that predisposes to the emergence of DD; on the contrary, they could be an adaptive deficit that develops later in individuals who do not read sufficiently due to dyslexia. In order to draw strong causal inferences, future longitudinal studies should be conducted to monitor eye movement skills in at-risk children before they reach school age and to assess whether they are present before they start learning to read. Finally, we were not able to collect confirmatory data on the neurobiological mechanisms underlying some of the parameters we measured. For example, we were not able to correlate why the right eye OKR response was weak with structural/functional imaging in the brain. Similarly, we could not completely isolate the effect of attention levels and motivation of children with dyslexia on task performance; although our test protocol was short and non-monotonous, individual differences may have added some noise to the measurements. These issues could be further explored in the future with neuroimaging-guided eye-tracking or designs that separately measure attention-motivation variables. Despite these limitations, our study has several carefully planned strengths and offers important contributions to the literature. First, the children with dyslexia in our study were clinically diagnosed cases and the sample selection was meticulous. Additional diagnoses such as ADHD, visual impairment and intellectual disability, which can often accompany dyslexia, were excluded from the study. Thus, we tried to ensure that the eye movement differences we obtained were as specifically related to dyslexia as possible. In this respect, our design provides a cleaner sample and can isolate dyslexia-specific features. Second, the assessments were performed with objective VNG and quantitative parameters such as saccadic rate, latency, accuracy, OKR were measured with precision. These measurements, which are not based on human observation or subjective scoring, increase the reliability of our results. Third, while our use of a non-reading task protocol can be considered a limitation, it also has some advantages and should be considered as a strength of the study. Since many studies have examined eye movements during reading or with linguistic stimuli, it remains controversial whether the differences obtained are a reflection of difficulty in reading or an underlying disorder. Finally, our study contributed to a holistic profile of the oculomotor system in dyslexia by including OKR, a component that has been relatively little studied in the literature. In particular, the lateralized OKR difference we found may lead to new research questions by pointing to a neurological difference that has not received much attention before. In all these aspects, our study is powerful research that both contributes to theoretical knowledge and may have practical outcomes. The objective findings we obtained have the potential to be used in dyslexia screening and diagnosis processes in the future and may also provide valuable information to monitor the effectiveness of interventions aimed at eliminating reading difficulties. Thus, we provide data supporting the importance of a multidimensional intervention approach to dyslexia (focusing not only on phonological training but also on visual-motor skills). Declarations Ethical Approval and Informed Consent: This study was approved by the Clinical Research Ethics Committee of Gulhane Training and Research Hospital (Date: 12.10.2022, Decision No: 2022/135). Written informed consent was obtained from the parents of all participating children. Author Contributions: MSU, MD, CK and SB contributed to the conceptualization and design of the study. MSU and CK performed data collection and VNG measurements and performed statistical analyses. MD interpreted the results and wrote the manuscript. All authors contributed to the writing of the manuscript, reviewed drafts and approved the final version. Conflict of Interest: The authors declare that there is no conflict of interest related to this study. Funding: No specific external funding or funding support was received for this research. Data Sharing: The data used in the study may be shared by the responsible author upon reasonable request. References Adi, N. S., Othman, A., Kuay, H. S., & Mustafa, Q. M. (2024). A study on the psychological functioning of children with specific learning difficulties and typically developing children. 12BMC Psychology , (1). https://doi.org/10.1186/s40359-024-02151-4 Ashburn, S. M., Flowers, D. L., Napoliello, E. M., & Eden, G. F. (2020). Cerebellar function in children with and without dyslexia during single word processing. 41Human Brain Mapping , (1), 120-138. https://doi.org/10.1002/hbm.24792 Ashidiqi, A. S., Widaningrum, I., & Karaman, J. (2023). Implementation of The Certainty Factor Method in The Expert System For Early Diagnosis of Dyslexia in Childhood. INTENSIF: 7Jurnal Ilmiah Penelitian Dan Penerapan Teknologi Sistem Informasi , (1), 18-32. https://doi.org/10.29407/intensif.v7i1.18433 Bilbao, C., Carrera, A., Otin, S., & Piñero, D. P. (2024). Eye Tracking-Based Characterization of Fixations during Reading in Children with Neurodevelopmental Disorders. 14Brain Sciences , (8). https://doi.org/10.3390/brainsci14080750 Blythe, H. I., Kirkby, J. A., & Liversedge, S. P. (2018). Comments on: "what is developmental dyslexia?" brain sci. 2018, 8, 26. the relationship between eye movements and reading difficulties. 8Brain Sciences , (6). https://doi.org/10.3390/brainsci8060100 Bonifacci, P., Tobia, V., Sansavini, A., & Guarini, A. (2023). Eye-Movements in a Text Reading Task: A Comparison of Preterm Children, Children with Dyslexia and Typical Readers. 13Brain Sciences , (3). https://doi.org/10.3390/brainsci13030425 Bucci, M. P. (2021). Visual training could be useful for improving reading capabilities in dyslexia. 10Applied Neuropsychology: Child , (3), 199-208. https://doi.org/10.1080/21622965.2019.1646649 Bucci, M. P., 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. 7PLoS ONE , (3), 1-8. https://doi.org/10.1371/journal.pone.0033458 Caldani, S., Gerard, C. L., Peyre, H., & Bucci, M. P. (2020). Visual attentional training improves reading capabilities in children with dyslexia: An eye tracker study during a reading task. 10Brain Sciences , (8), 1-13. https://doi.org/10.3390/brainsci10080558 Ceple, I., Krauze, L., Serpa, E., Svede, A., Goliskina, V., Vasiljeva, S., Kassaliete, E., Ganebnaya, A., Volberga, L., Truksa, R., Ruza, T., & Krumina, G. (2025). Eye Movement Parameters in Children with Reading Difficulties. 15Applied Sciences (Switzerland) , (2). https://doi.org/10.3390/app15020954 Chi, J., Reed, D. K., & Mcbride, C. (2025). The effects of orthography , phonology , semantics , and working memory on the reading comprehension of children with and without reading dyslexia. 0123456789Annals of Dyslexia , . https://doi.org/10.1007/s11881-025-00322-5 Coenen, L., Grünke, M., Becker-Genschow, S., Schlüter, K., Schulden, M., & Barwasser, A. (2024). A Systematic Review of Eye-Tracking Technology in Dyslexia Diagnosis. 21Insights into Learning Disabilities , (1), 45-65. www.ldworldwide.org. Dalvand, H., Chamani, N., Rahsepar-Fard, K., Khorrami-Nejad, M., & Dadgar, H. (2023). The effect of online visual games on visual perception, oculomotor, and balance skills of children with developmental dyslexia during the COVID-19 pandemic. 43International Ophthalmology , (12), 5011-5024. https://doi.org/10.1007/s10792-023-02904-x Demir, İ., Cengiz, D. U., Demir, A. Ç., Çolak, S. C., Birişik, S. D., & Özcan, Ö. Ö. (2023). Vestibular Evaluation of Children Diagnosed with Specific Learning Disorder. Alpha Psychiatry , 24 (5), 211. Doettl, S. M., & McCaslin, D. L. (2018). Oculomotor Assessment in Children. 39Seminars in Hearing , (3), 275-287. https://doi.org/10.1055/s-0038-1666818 Doettl, S. M., Plyler, P. N., McCaslin, D. L., & Schay, N. L. (2015). Pediatric oculomotor findings during monocular videonystagmography: A developmental study. 26Journal of the American Academy of Audiology , (8), 703-715. https://doi.org/10.3766/jaaa.14089 Eden, G. F., Stein, J. F., Wood, H. M., & Wood, F. B. (1994). Differences in eye movements and reading problems in dyslexic and normal children. 34Vision Research , (10), 1345-1358. https://doi.org/10.1016/0042-6989(94)90209-7 El Hmimdi, A. E., Ward, L. M., Palpanas, T., & Kapoula, Z. (2021). Predicting dyslexia and reading speed in adolescents from eye movements in reading and non-reading tasks: A machine learning approach. 11Brain Sciences , (10). https://doi.org/10.3390/brainsci11101337 Fella, A., Loizou, M., Christoforou, C., & Papadopoulos, T. C. (2023). Eye Movement Evidence for Simultaneous Cognitive Processing in Reading. 10Children , (12), 1-17. https://doi.org/10.3390/children10121855 Görker, I., Bozatli, L., Korkmazlar, Ü., Yücel Karadag, M., Ceylan, C., Söğüt, C., Aykutlu, H. C., Subay, B., & Turan, N. (2017). The probable prevalence and sociodemographic characteristics of specific learning disorder in primary school children in edirne. 54Noropsychiatry Archives , (4), 343-349. https://doi.org/10.5152/npa.2016.18054 Granet, D. B. (2011). Learning disabilities, dyslexia, and vision: The role of the pediatric ophthalmologist. 15Journal of AAPOS , (2), 119-120. https://doi.org/10.1016/j.jaapos.2011.03.003 Grigorenko, E. L., Fuchs, L. S., Willcutt, E. G., Compton, D. L., Wagner, R. K., & Fletcher, J. M. (2020). Understanding, Educating, and Supporting Children With Specific Learning Disabilities: 50 Years of Science and Practice. 75American Psychologist , (1), 37-51. https://doi.org/10.1037/amp0000452 Ibrahimi, D., Aviles, M., & Rodríguez-Reséndiz, J. (2024). Oculomotor Patterns in Children with Poor Reading Abilities Measured Using the Development Eye Movement Test. 13Journal of Clinical Medicine , (15). https://doi.org/10.3390/jcm13154415 Jafarlou, F., Ahadi, M., & Jarollahi, F. (2021). Eye movement patterns in Iranian dyslexic children compared to non-dyslexic children. 48Auris Nasus Larynx , (4), 594-600. https://doi.org/10.1016/j.anl.2020.11.012 Jothi Prabha, A., & Bhargavi, R. (2020). Predictive Model for Dyslexia from Fixations and Saccadic Eye Movement Events. 195Computer Methods and Programs in Biomedicine , . https://doi.org/10.1016/j.cmpb.2020.105538 Macambira, Y. K. dos S., Barbosa, J. V. dos S., Queiroga, B. M. de, Cordeiro, A. A. de A., Menezes, D. C., Lima, M. L. L. T. de, & Advíncula, K. P. (2022). Ocular findings from otoneurological examinations in children with and without dyslexia: a systematic review with meta-analysis. 88Brazilian Journal of Otorhinolaryngology , , S192-S201. https://doi.org/10.1016/j.bjorl.2021.10.006 Miladinović, A., Quaia, C., Ajčević, M., Diplotti, L., Cumming, B. G., Pensiero, S., & Accardo, A. (2022). Ocular-following responses in school-age children. 17PLoS ONE , (November 11), 1-15. https://doi.org/10.1371/journal.pone.0277443 Nas Özütemiz, G., Açıksöz Yay, Ş. Ö., Öz, I., Akın Sarı, B., Ayraler Taner, H., & Çakmak, E. (2025). The effect of dynamic visual acuity on rapid naming in school-aged children with dyslexia. 190International Journal of Pediatric Otorhinolaryngology , (January). https://doi.org/10.1016/j.ijporl.2025.112253 Natrayan, R., & Chauhan, A. K. (2025). Exploring the role of the vestibular system in visuospatial memory in developmental dyslexia: 58 Narrative review. Journal of Associated Medical Sciences , (1), 177-184. https://doi.org/10.12982/JAMS.2025.019 Nerušil, B., Polec, J., Škunda, J., & Kačur, J. (2021). Eye tracking based dyslexia detection using a holistic approach. 11Scientific Reports , (1), 1-10. https://doi.org/10.1038/s41598-021-95275-1 Nguyen, T. K. C., Le, D. D., Le, T. H., Nguyen, T. C. H., & Ngo, T. D. (2024). 0 The use of eye tracking in supporting individuals with dyslexia: a review. Disability and Rehabilitation: Assistive Technology , (0), 1-16. https://doi.org/10.1080/17483107.2024.2437697 Nicolson, R. I., Fawcett, A. J., & Dean, P. (2001). Developmental dyslexia: The cerebellar deficit hypothesis. 24Trends in Neurosciences , (9), 508-511. https://doi.org/10.1016/S0166-2236(00)01896-8 Odegard, T. N., Farris, E. A., & Middleton, A. E. (2024). Dyslexia in the 21st century: revisiting the consensus definition. Annals of Dyslexia , 273-281. https://doi.org/10.1007/s11881-024-00316-9 Ölçek, G., Çelik, İ., Başoǧlu, Y., Kaymakçı, S., & Gürlek, E. (2023). Comparison of children with and without dyslexia using functional head impulse test and pediatric balance scale. 14Frontiers in Neurology , . https://doi.org/10.3389/fneur.2023.1153650 Pavlidis, G. T. (1981). Do eye movements hold the key to dyslexia? 19Neuropsychologia , (1), 57-64. https://doi.org/10.1016/0028-3932(81)90044-0 Pensiero, S., Accardo, A., Michieletto, P., & Brambilla, P. (2013). Saccadic Alterations in Severe Developmental Dyslexia. 2013Case Reports in Neurological Medicine , , 1-5. https://doi.org/10.1155/2013/406861 Picciotti, P. M., Mele, D. A., Settimi, S., Mari, G., D'Alatri, L., & Galli, J. (2024). Subjective visual vertical/horizontal and video head impulse test in dyslexic children. 30Dyslexia , (4), 1-12. https://doi.org/10.1002/dys.1782 Piko, B. F., & Dudok, R. (2023). Strengths and Difficulties among Adolescent with and without Specific Learning Disorders (SLD). 10Children , (11), 1-14. https://doi.org/10.3390/children10111741 Protasevica, D., Kassaliete, E., Klavinska, A., Alecka, M., Berzina, A., Goliskina, V., Koleda, M., Mikelsone, R., Ozola, E., Ruza, T., Serpa, E., Svede, A., Toloka, D., Vasiljeva, S., Volberga, L., Ceple, I., & Krumina, G. (2024). The Computerized Developmental Eye Movement (DEM) Test: Normative Data for School-Aged Children. 8Vision , (3), 47. https://doi.org/10.3390/vision8030047 Rodríguez, K., Fonseca, L., Iaconis, F.-R., Del-Punta, J., & Gasaneo, G. (2025). Eye tracking studies, a way to understand difficulties in reading processing. 24Ocnos , (1). https://doi.org/10.18239/ocnos_2025.24.1.488 Salem, T., Elsherif, M., Mourad, M., Abdou, R., & Hamouda, N. (2022). Eye movements and visual perception in dyslexic children. 20Hearing, Balance and Communication , (2), 109-119. https://doi.org/10.1080/21695717.2022.2028496 Seassau, M., Gérard, C. L., Bui-Quoc, E., & Bucci, M. P. (2014). Binocular saccade coordination in reading and visual search: A developmental study in typical reader and dyslexic children. 8Frontiers in Integrative Neuroscience , (October), 1-11. https://doi.org/10.3389/fnint.2014.00085 Sinno, S., Najem, F., Abouchacra, K. S., Perrin, P., & Dumas, G. (2020). Normative Values of Saccades and Smooth Pursuit in Children Aged 5 to 17 Years. 31Journal of the American Academy of Audiology , (6), 384-392. https://doi.org/10.3766/jaaa.19049 Snowling, M. J., Hulme, C., & Nation, K. (2020). Defining and understanding dyslexia: past, present and future. 46Oxford Review of Education , (4), 501-513. https://doi.org/10.1080/03054985.2020.1765756 Stein, J. (2019). The current status of the magnocellular theory of developmental dyslexia. 130Neuropsychologia , (September 2017), 66-77. https://doi.org/10.1016/j.neuropsychologia.2018.03.022 Stein, J. (2023). Theories about Developmental Dyslexia. 13Brain Sciences , (2). https://doi.org/10.3390/brainsci13020208 Stella, M., & Engelhardt, P. E. (2021). Comprehension and eye movements in the processing of subject-and object-relative clauses: Evidence from dyslexia and individual differences†. 11Brain Sciences , (7). https://doi.org/10.3390/brainsci11070915 Svaricek, R., Dostalova, N., Sedmidubsky, J., & Cernek, A. (2025). INSIGHT: Combining Fixation Visualizations and Residual Neural Networks for Dyslexia Classification From Eye-Tracking Data. 31Dyslexia , (1), 1-14. https://doi.org/10.1002/dys.1801 Tiadi, A., Seassau, M., Bui-Quoc, E., Gerard, C. L., & Bucci, M. P. (2014). Vertical saccades in dyslexic children. 35Research in Developmental Disabilities , (11), 3175-3181. https://doi.org/10.1016/j.ridd.2014.07.057 Tobener, E., Searer, A., Doettl, S., & Plyler, P. (2024). Oculomotor Findings in Videonystagmography across the Lifespan. In Journal of the American Academy of Audiology. https://doi.org/10.1055/s-0042-1760437 Toki, E. I. (2024). Using Eye-Tracking to Assess Dyslexia: A Systematic Review of Emerging Evidence. 14Education Sciences , (11). https://doi.org/10.3390/educsci14111256 Trauzettel-Klosinski, S., Koitzsch, A. M., Dürrwächter, U., Sokolov, A. N., Reinhard, J., & Klosinski, G. (2010). 88 Eye movements in German-speaking children with and without dyslexia when reading aloud . Acta Ophthalmologica , (6), 681-691. https://doi.org/10.1111/j.1755-3768.2009.01523.x Ünal, F., Öktem, F., Çuhadaroğlu, F. Ç., Kültür, S. E. Ç., Akdemİr, D., Özdemİr, D. F., Çak, H. T., Ünal, D., Tiraş, K., Aslan, C., & Kalayci, B. M. (2019). Validity and Reliability of the Turkish Adaptation of the Affective Disorders and Schizophrenia Interview Schedule for School Age Children - Now and Lifetime Form - DSM - 5 November 2016 - Turkish Adaptation (ÇDŞG - ŞY - DSM - 5 - T). Turkish Journal of Psychiatry , 30 (1), 42–50. Vagge, A., Cavanna, M., Traverso, C. E., & Iester, M. (2015). Evaluation of ocular movements in patients with dyslexia. 65Annals of Dyslexia , (1), 24-32. https://doi.org/10.1007/s11881-015-0098-7 Vaitheeshwari, R., Chih-Hsuan, C., Chung, C. R., Yang, H. Y., Yeh, S. C., Wu, E. H. K., & Kumar, M. (2024). Dyslexia Analysis and Diagnosis Based on Eye Movement. 32IEEE Transactions on Neural Systems and Rehabilitation Engineering , , 4109-4119. https://doi.org/10.1109/TNSRE.2024.3496087 Vikesdal, G. H., Falkenberg, H. K., Mon-Williams, M., Riddell, P., & Langaas, T. (2021). Normal saccades but decreased fixation stability in a population of children with dyslexia. 14 (2), 1–7. Scandinavian Journal of Optometry and Visual Science , https://doi.org/10.5384/sjovs.v14i2.137 Vinuela-Navarro, V., Erichsen, J. T., Williams, C., & Woodhouse, J. M. (2017). Saccades and fixations in children with delayed reading skills. 37Ophthalmic and Physiological Optics , (4), 531-541. https://doi.org/10.1111/opo.12392 Virlet, L., Sparrow, L., Barela, J., Berquin, P., & Bonnet, C. (2024). Proprioceptive intervention improves reading performance in developmental dyslexia: An eye-tracking study. 153Research in Developmental Disabilities , (October 2023), 104813. https://doi.org/10.1016/j.ridd.2024.104813 Wang, H., Liu, F., Dong, Y., & Yu, D. (2022). Entropy of eye movement during rapid automatized naming. 16Frontiers in Human Neuroscience , (August), 1-12. https://doi.org/10.3389/fnhum.2022.945406 WU, Y. J., YANG, W. H., WANG, Q. X., YANG, D. S., HU, X. Y., JING, J., & LI, X. H. (2018). Eye-movement Patterns of Chinese Children with Developmental Dyslexia during the Stroop Test. 31Biomedical and Environmental Sciences , (9), 677-685. https://doi.org/10.3967/bes2018.092 Xia, Z., Hoeft, F., Zhang, L., & Shu, H. (2016). Neuroanatomical anomalies of dyslexia: Disambiguating the effects of disorder, performance, and maturation. 81Neuropsychologia , , 68-78. https://doi.org/10.1016/j.neuropsychologia.2015.12.003 Yang, L. P., Li, C. B., Li, X. M., Zhai, M. M., Zhao, J., & Weng, X. C. (2022). Prevalence of developmental dyslexia in primary school children: a protocol for systematic review and meta-analysis. 18World Journal of Pediatrics , (12), 804-809. https://doi.org/10.1007/s12519-022-00572-y Tables Tables 1 to 2 are available in the Supplementary Files section Additional Declarations The authors declare no competing interests. Supplementary Files Tables.docx Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6526788","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":453387229,"identity":"6deabbf5-c703-43df-916d-d946bf58b6b7","order_by":0,"name":"Melikşah Safa Üçok","email":"","orcid":"","institution":"Elbistan State Hospital","correspondingAuthor":false,"prefix":"","firstName":"Melikşah","middleName":"Safa","lastName":"Üçok","suffix":""},{"id":453387230,"identity":"446538ae-80a5-4b0f-bb75-ae556953f6e1","order_by":1,"name":"Mustafa Dinçer","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBUlEQVRIiWNgGAWjYDCCw0jsDwwMzHIgxoEHRGlhY2CcAdRiDNaSgE/LATQtiQ0gDj4tfMd5D374uGdb4vz5zQ8bfuZYp88PO/wQaIudnG4Ddi2Sh/mSJWc8u5244RibYWPvtvTcjbfTDIBako3NDmDXYnCYx4yZ5wBQCxuD+QPebYdzN85OAGk5kLgNn5Y/QC3z29g/Nv7ddjjdcHb6B8JaGIBaGo7xGDYDbUmQl87Bb4vkYR5jyZ4Dt403HMspbJbdlm64QTqn4ECCAW6/8J0/Y/jhx4HbsvObj29sfLvNWl5+dvrmDx8q7ORwacHiVLBKA2KVg4B8AymqR8EoGAWjYCQAALdXaysGNy1mAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-6056-8157","institution":"Adnan Menderes University","correspondingAuthor":true,"prefix":"","firstName":"Mustafa","middleName":"","lastName":"Dinçer","suffix":""},{"id":453387231,"identity":"7aab2d4b-795f-4520-a186-60471766824c","order_by":2,"name":"Ceren Karaçaylı","email":"","orcid":"","institution":"Gülhane Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ceren","middleName":"","lastName":"Karaçaylı","suffix":""},{"id":455570766,"identity":"aa135e61-4fea-494e-a136-b0386b886d75","order_by":3,"name":"Esra Güngör Bağlıcakoğlu","email":"","orcid":"","institution":"Department of Child and Adolescent Psychiatry, Ankara Etlik City Hospital, Ankara, Türkiye","correspondingAuthor":false,"prefix":"","firstName":"Esra","middleName":"Güngör","lastName":"Bağlıcakoğlu","suffix":""},{"id":453387232,"identity":"2b861077-f532-4fa8-a57e-49303bbd3fd1","order_by":4,"name":"Şahin Bodur","email":"","orcid":"","institution":"Gülhane Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Şahin","middleName":"","lastName":"Bodur","suffix":""},{"id":455570767,"identity":"53980c44-66bf-4455-bb21-877c66b2ca02","order_by":5,"name":"Mehmet Ayhan Cöngöloğlu","email":"","orcid":"","institution":"Gülhane Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mehmet","middleName":"Ayhan","lastName":"Cöngöloğlu","suffix":""}],"badges":[],"createdAt":"2025-04-25 08:11:40","currentVersionCode":2,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6526788/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-6526788/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82728974,"identity":"227da346-f174-4343-a895-3033a4b16dfd","added_by":"auto","created_at":"2025-05-14 14:30:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":585828,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6526788/v2/9f10fac2-f4e4-4d96-b823-ce8138ce78ef.pdf"},{"id":82727750,"identity":"04fc3688-e186-403f-88c8-508f905398ff","added_by":"auto","created_at":"2025-05-14 14:22:18","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":25900,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-6526788/v2/2d1de423e83719debaed4245.docx"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"Oculomotor Dysfunctions in Non-Reading Tasks in Children with Developmental Dyslexia: Saccadic and Optokinetic Findings","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eDevelopmental dyslexia (DD) is a specific learning disorder (SLD) defined as an individual's inability to develop reading or writing skills adequately despite adequate intellectual capacity and appropriate education. Although studies on the prevalence of DD may vary due to reasons such as the population studied, screening and diagnostic methods, and the orthographic structure of the language, the prevalence between the ages of 6\u0026ndash;13 is reported to be around 7.1% (Yang et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The difficulties experienced by individuals with DD not only hinder their academic performance. They also affect their cognitive and psychological development throughout life, leading to long-term consequences (Adi et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Piko \u0026amp; Dudok, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Snowling et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). In order to minimize these long-term consequences, diagnosis and intervention at the earliest possible age becomes crucial to significantly change the educational trajectory and self-esteem of affected individuals (Virlet et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Although traditional methods used in the diagnosis of DD are very important in terms of diagnosis, they can create problems by potentially disadvantaging some individuals due to subjective interpretation of the results and sometimes not taking cultural and linguistic diversity into account. Therefore, there is an increasing need for early diagnosis with objective methods and individualized interventions for etiology (Bucci, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Caldani et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Dalvand et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Grigorenko et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Nguyen et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Virlet et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eTheories about the etiology of DD have been debated for many years (Stein, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The biggest problem in DD is the ability to separate words into their component sounds and to associate letters and sounds with phonological awareness. Although there is strong scientific evidence that dyslexia is explained by the phonological coding deficit theory, this theory alone cannot explain all cases (Chi et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Stein, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). One of the alternative approaches, the magnocellular theory, argues that a defect in the magnocellular system in the timing of visual events and the control of eye movements during reading may lead to difficulties with visual motion sensitivity and binocular stability, resulting in abnormal eye movements in individuals with dyslexia. Deficits in the perception of fast visual information may affect eye movements in individuals with DD (Coenen et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). A poor strategy in visual information processing has been suggested to be the cause of the abnormal eye movements observed in children with DD. On the contrary, the hypothesis of impairment of the visual system is still controversial in terms of causality, as differences in eye movements may also affect the perception of visual information (Ceple et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Eden et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Granet, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Ibrahimi et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Jafarlou et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Stella \u0026amp; Engelhardt, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Vagge et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Vikesdal et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Individuals with DD show deficits not only in phoneme processing but also in oculomotor skills (Nguyen et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Some studies have reported visual and oculomotor differences in children with DD, suggesting that there may be dysfunction in the oculomotor system as well as deficits in the magnocellular system (Coenen et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Demir et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; \u0026Ouml;l\u0026ccedil;ek et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In this context, it has been shown that oculomotor patterns in DD differ from normal not only during the reading task but also in the pursuit of sequentially moving light targets (Jafarlou et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Therefore, eye movement control, which is known to be impaired in DD, should be considered independently of phonological awareness (Bucci, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eDuring reading, the eyes need to fixate on the words, perform correct saccadic movements and focus and align both eyes. The oculomotor system, which is among the most critical structures in this process, enables the individual to track visual targets, fixate on words and quickly switch to different targets when necessary. During the functioning of this system, eye movements need to be regulated in an integrated manner with inputs from both the cerebellar and vestibular systems. In particular, the cerebellum regulates the accuracy and timing of saccadic movements, while the vestibular system maintains visual stability by counterbalancing head and body movements (Doettl et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Doettl \u0026amp; McCaslin, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Tobener et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). These neuroanatomical systems work together to provide the function of three basic eye movements: fixation, saccadic movements and smooth pursuit.\u003c/p\u003e \u003cp\u003eEarly studies suggested that children with DD exhibit irregular eye movements outside of reading tasks and that a general oculomotor dysfunction should be considered due to motor coordination deficits and gaze instability (Pavlidis, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1981\u003c/span\u003e). In addition to impairments in motor automation and timing in some individuals with DD, it has been suggested that the likelihood of vestibular dysfunction is higher in these children (Natrayan \u0026amp; Chauhan, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). In oculomotor dysfunction, more attentional resources are required to overcome the coordination imbalance, which may reduce the resources needed for cognitive tasks. It may also cause cognitive resources to be used for motor control instead of attention, negatively affecting reading performance. Studies show that deficits especially in horizontal eye tracking movements, affect reading fluency and accuracy (Fella et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Rodr\u0026iacute;guez et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). DD have been observed to exhibit longer and more numerous fixations, shorter saccades and more frequent backward eye movements (Bonifacci et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Oculomotor dysfunction has been reported as a significant factor in children with poor reading skills even in the absence of a formal diagnosis of a learning disorder (Ibrahimi et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Although it has been suggested that abnormal eye movements in DDs are often a consequence of reading difficulties and not the cause, the absence of impairments in non-verbal targets is expected, but this is not the case, suggesting that there may be a general deficit in oculomotor skills (Vikesdal et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eRecently, studies on the use of eye tracking technology in terms of objective diagnostic approach have been increasing (Ashburn et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Ashidiqi et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Bilbao et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Bonifacci et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Caldani et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Ceple et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Coenen et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; El Hmimdi et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Fella et al, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Ibrahimi et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Jafarlou et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Jothi Prabha \u0026amp; Bhargavi, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Macambira et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Nerušil et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Protasevica et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Rodr\u0026iacute;guez et al, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Stella \u0026amp; Engelhardt, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Svaricek et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Toki, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Vaitheeshwari et al., \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Vikesdal et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Virlet et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Advances in eye-tracking technology have enabled more objective assessment of oculomotor parameters such as fixation stability, saccadic latency and tracking accuracy in individuals with SLD. High-resolution systems such as videonystagmography (VNG) can facilitate the investigation of saccadic eye movement abnormalities, contributing to a better understanding of their relationship with reading difficulties and identifying new biomarkers for early diagnosis and intervention (Dalvand et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Jafarlou et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Macambira et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The methodologies used to understand the relationship between SLD and eye movements vary considerably. It is not clear whether changes in eye movements in individuals with DD are solely related to the reading process or are the result of a general neurobiological dysfunction. Therefore, in order to understand the normal functioning of eye movements during reading, it is necessary to examine how saccadic movements function in nonreading tasks as well\u003c/p\u003e \u003cp\u003eThe current study aims to evaluate saccadic eye movement abnormalities in children diagnosed with DD compared to a healthy control group. In particular, we will investigate whether parameters such as saccadic velocity, accuracy and latency can serve as potential diagnostic markers for children with DD using a non-reading task. Accordingly, eye movement data obtained with VNG of dyslectic and typically developing children will be compared. Only a single test protocol was used in order to keep motivation high, to reduce the involvement of higher-order cognitive processes associated with reading in eye movement performance, and to reduce distractor effects.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003e This case-control study was conducted between November 2022 and April 2023 after the approval of the Clinical Research Ethics Committee of G\u0026uuml;lhane Training and Research Hospital (Approval Date: October 12, 2022; Decision No: 2022/135). The study included 40 children between the ages of 8\u0026ndash;12 years diagnosed with DD from the Child and Adolescent Psychiatry outpatient clinic of G\u0026uuml;lhane Training and Research Hospital and 40 age-gender matched healthy controls. The diagnosis of DD was made by a child psychiatrist according to DSM-5 criteria and confirmed by a child and adolescent psychiatrist. Children in the control group had no history of psychiatric or neurologic disorders. Inclusion criteria were meeting the age limit, having normal cognitive capacity and meeting the diagnostic criteria for DD in the patient group, no concurrent psychiatric or neurological disorders, no condition affecting cognitive function, no history of epilepsy or head trauma, and no use of medications that could affect oculomotor function. To ensure the absence of additional psychiatric conditions, both groups underwent psychiatric evaluation using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version, DSM-5 -Turkish Adaptation (\u0026Uuml;nal et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eExperimental Procedure\u003c/h3\u003e\n\u003cp\u003eAssessments were performed in the hospital audiology laboratory using a videonystagmography (VNG) system (ICS Otometrics, Taastrup, Denmark) that incorporates high-resolution infrared cameras within a head-mounted goggle system to capture binocular eye movements in real time. Prior to testing, the system was calibrated using a laser dot fixation array to ensure precise gaze tracking. Participants were seated 120 cm from a stimulus display bar in a dimly lit room to minimize external visual distractions. The device operated at a sampling rate of 100 Hz, while saccades were detected using a velocity threshold of 40\u0026deg;/s and an acceleration threshold of 800\u0026deg;/s\u0026sup2;. Gain settings were kept at 150 \u0026micro;V/10\u0026deg;. Blinks were automatically detected and removed from the recording by an artifact rejection algorithm based on pupil closure. VNG is one of the laboratory tests that evaluate the vestibular system. However, VNG cannot evaluate the entire vestibular system; it only provides information about the vestibulo-ocular reflex. The test battery consists of oculomotor tests, gaze stabilization tests and positional tests. The oculomotor tests (saccade, pursuit and optokinetic tests) provide information, especially about central vestibular system function.\u003c/p\u003e\n\u003ch3\u003eSaccadic Eye Movement Test Procedure\u003c/h3\u003e\n\u003cp\u003eFor calibration, the participant was asked to look 30\u0026deg; to the right, left, above and below the center line of the light bar with the VNG goggles on, while keeping the head still. A 20-second recording was taken for each position. In addition, a spontaneous nystagmus test was performed in complete darkness with eyes open to detect abnormal involuntary eye movements. Participants were then presented with a visual target that randomly appeared in horizontal positions within \u0026plusmn;\u0026thinsp;15\u0026deg;-20\u0026deg; and had to make rapid saccadic movements to locate the target. Stimulus intervals were randomized between 3\u0026ndash;4 seconds to avoid anticipatory responses. The total recording time was one minute, during which time important saccadic parameters such as Saccadic Velocity (\u0026deg;/s), Saccadic Accuracy (%) and Saccadic Latency (ms) were obtained. In addition, the participant was asked to count the lights at fixed intervals on the light bar with his/her eyes and this process was recorded for 20 seconds. The calculation of asymmetry between the participant's right and left tracking traces was included. Optokinetic responses (OKR) were analyzed separately for the right and left eyes to examine potential asymmetries.\u003c/p\u003e\n\u003ch3\u003eData Processing and Analysis\u003c/h3\u003e\n\u003cp\u003eRecorded saccadic eye movements were processed using onboard ICS analysis software. Trials affected by excessive noise or blink artifacts were automatically removed prior to statistical analysis. All data analyses were performed using IBM SPSS Statistics (Version 26, IBM Corp., Armonk, NY, USA). Descriptive statistics were reported as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD), median (M), interquartile range (IQR) and minimum-maximum values. Depending on the data distribution, group comparisons were made using parametric (independent samples t-test) or nonparametric (Mann-Whitney U test) methods. Chi-square test was used for categorical variables. The overall statistical significance level was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003e\u003cstrong\u003eDescriptive Statistics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 80 children, 40 children diagnosed with DD and 40 healthy controls, participated in the study. As presented in Table 1, the ages of the participants ranged between 8 and 12 years. The mean age of the DD group was 9.5 ± 1.4 years, while the mean age of the control group was 9.9 ± 1.4 years, and there was no statistically significant difference between the groups (p = 0.276). The proportion of female participants was 60.0% (n = 24) in the DD group and 62.5% (n = 25) in the control group, and no significant difference was found between the groups (p \u0026gt; 0.999).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEye Movement Findings\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChildren with DD exhibited significantly lower saccadic velocity compared to the control group (M = 307.5°/s, SD = 47.5 vs. M = 453.5°/s, SD = 85.0; p \u0026lt; 0.001). Similarly, saccadic accuracy was reduced in the SLD group (M = 71.5%, SD = 13.0) compared to the control group (M = 98.5%, SD = 8.5; p \u0026lt; 0.001). In addition, saccadic latency was significantly prolonged in children with DD (M = 260.0 ms, SD = 104.0) compared to the control group (M = 131.5 ms, SD = 30.0; p \u0026lt; 0.001). In terms of OKR, right eye responses were significantly lower in the DD group compared to the control group (p = 0.028), but no significant difference was observed in left eye responses (p = 0.067). However, the percentage difference in OKR between the right and left eyes was significantly higher in the DD group compared to the control group (p = 0.049) (Table-2).\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe findings of this study show that children with DD exhibit marked oculomotor differences even in simple visual tasks that do not involve reading. The DD group showed significantly slower saccadic eye movement velocity, lower saccadic accuracy and prolonged saccadic latency compared to the control group. In addition, OKR were also abnormal in DD; especially the right eye OKR response was attenuated, whereas there was no significant difference in the left eye. These findings suggest that there are differences in eye movement functions in DD even in a task independent of reading, suggesting that dyslexia may not only be a phonological disorder but also a comprehensive neurodevelopmental difference affecting visual-motor systems.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSaccadic Eye Movements: Velocity, Accuracy and Latency\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePrevious research has reported that individuals with DD have lower saccade velocity and accuracy rate and longer saccade latency than normal readers in various eye movement tasks (Demir et al., 2023; G\u0026ouml;rker et al., 2017; Jafarlou et al., 2021; \u0026Ouml;l\u0026ccedil;ek et al., 2023; Tiadi et al., 2014). It has also been suggested that while saccadic latency shortens with age in typical children, there may be a slowdown in this developmental trajectory in those with DD (Ceple et al., 2025; Miladinović et al., 2022; Sinno et al., 2020).\u0026nbsp;The longer time requirement for target orientation suggests slow processing in the brain\u0026apos;s relevant networks (Pensiero et al., 2013).\u0026nbsp;The findings of a study that observed that DD exhibited different saccadic eye movements in pursuit of moving targets compared to the control group suggest that there may be a deficit in processing moving visual stimuli in dyslexia (Jafarlou et al., 2021).\u0026nbsp;In our study, healthy children were largely accurate in getting saccades to the target point, whereas those with DD were less accurate. This suggests that people with DD have difficulty in precisely controlling their eye movements (Jafarlou et al., 2021; Macambira et al., 2022) .\u0026nbsp;Such inaccurate saccadic behaviors could be an explanation for the regression movements and prolonged fixations also observed during reading. Indeed, it has been consistently reported across different languages and orthographies that individuals with dyslexia exhibit shorter amplitude saccades (not reaching the target) and frequent regression movements during reading (Pavlidis, 1981; Seassau et al., 2014; Trauzettel-Klosinski et al., 2010; Vagge et al., 2015; Vikesdal et al., 2021; WU et al., 2018).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOptokinetic Responses (OKR) Asymmetry and Vestibular Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnother remarkable finding of our study was the asymmetry in the OKR. Children with DD exhibited significantly poorer OKR in the right eye, whereas it was almost normal in the left eye. This difference suggests that there may be an imbalance in the connectivity between the hemispheres in visual processing in DD. It has been suggested that structural and functional abnormalities are more pronounced in the left hemisphere compared to the right in DD (Xia et al., 2016) .\u0026nbsp;Under normal conditions, both eyes and both hemispheres contribute symmetrically to the tracking of visual movements; however, our study shows that in DD, a sufficiently strong response to moving stimuli tracked by the right visual field is not produced. This may be a reflection of left hemisphere dysfunction. As the left hemisphere is dominant in language processing, it also has a certain dominant role in visuomotor integration (Stein, 2023).\u0026nbsp;In the case of a developmental deficit in the left hemisphere, the right-sided visual field may be affected, to relatively poor OKR. On the other hand, Salem et al. reported that there was no difference between dyslexic and control children in terms of OKR speed acquisition (Salem et al., 2022).\u0026nbsp;Nevertheless, there is a need for further investigation of OKR in DD, which is a subject that has been little studied in the literature (Demir et al., 2023). If this asymmetry is consistently demonstrated in research, new light will be shed on the hitherto relatively neglected issues of binocular visual processing and hemispheric lateralization in the neurobiology of dyslexia.\u003c/p\u003e\n\u003cp\u003eThe OKR is an eye movement response that results from the close interaction of visual-motor integration and the vestibular system. In a moving visual environment, it works together with the vestibulo-ocular reflex (VOR) to stabilize the image on the retina. The fact that we observe a weak OKR in the right eye in children with dyslexia may also indicate an integration problem originating from the vestibular system. Recent research has drawn attention to the role of vestibulo-ocular integration in learning disorders such as dyslexia (Bilbao et al, 2024;\u0026nbsp;Demir et al., 2023; Macambira et al., 2022; Nas \u0026Ouml;z\u0026uuml;temiz et al., 2025; Natrayan \u0026amp; Chauhan, 2025; \u0026Ouml;l\u0026ccedil;ek et al., 2023; Picciotti et al., 2024). In particular, it has been suggested that the coordination between the vestibular system and eye movements may be poor in children with dyslexia and this may contribute to both visual attention and postural balance problems. Although our finding does not directly measure vestibular function, it indirectly supports this view. The asymmetry in OKR may be due to deficits in the integration of vestibular inputs with oculomotor control. Recently, in studies evaluating vestibular system functions in children with DD, it was reported that these children performed poorly in vestubulo-ocular integration tests compared to the control group (Demir et al., 2023; \u0026Ouml;l\u0026ccedil;ek et al., 2023). The vestibular system facilitates line tracking during reading through the VOR, which allows the eyes to be stabilized despite head and body movements. If there is a weakness in vestibulo-ocular integration in dyslexia, this may both disrupt the stability of eye movements and increase problems such as line skipping and misalignment during reading. Future electrophysiologic or imaging-based studies that more directly examine the relationship between the vestibular system and oculomotor control in individuals with dyslexia will help to elucidate the underlying mechanisms of our findings.\u003c/p\u003e\n\u003cp\u003eSome studies have not found significant differences between DD groups and controls in terms of eye movements (Ceple et al., 2025; Vinuela-Navarro et al., 2017).\u0026nbsp;Such contradictory results may be due to the inclusion of subjects who have not been diagnosed with \u0026quot;dyslexia\u0026quot; in groups with reading difficulties, such as poor readers for various reasons, or the heterogeneous composition of the subjects, masking the true dyslexia-specific eye movement differences. Moreover, they may have included comorbidities such as attention deficit hyperactivity disorder (ADHD), anxiety disorder and other psychopathologies without fully differentiating them. In our study, we tried to obtain a homogeneous sample with a definite diagnosis as much as possible by using the DD group who had significant reading difficulties to the extent that they presented to a child-adolescent psychiatrist and whose diagnosis was clearly established afterwards and whose comorbid conditions were excluded. In this way, we believe that we were able to observe more clearly the saccadic differences that can only be attributed to dyslexia. Although our findings are consistent with many previous studies, we think that the different results may be due to the methodology or sample used in the studies.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTheoretical Framework\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe classic explanation of DD focuses on a specific deficit in the areas of phonological awareness and language processing.\u0026nbsp;According to this approach, linguistic encoding problems are at the root of reading difficulties and other symptoms such as eye movement abnormalities are considered as secondary manifestations. However, our findings provide evidence that eye movement control in children with DD can be impaired independently of phonological processes. Our use of a non-reading task showed that children with dyslexia exhibit abnormal eye movement profiles even without any reading. In the literature some theoretical approaches have suggested that audiovisual sensory anomalies in dyslexia may be a separate component from phonological impairment (Stein, 2023). In particular, by emphasizing that impairment in the dorsal visual flow pathways in dyslexia is a factor in itself, he argued that reading disability is not only a phonological but also a visual-motor learning problem. This view is not shared by all researchers (Blythe et al., 2018).\u0026nbsp;Eye movement abnormalities in DD, at least some of them, should not be treated as a consequence of phonological deficits, but rather as a direct indication of a neurodevelopmental difference. Of course, even if the main difficulty in dyslexia is phonological language processing (Chi et al., 2025),\u0026nbsp;a one-dimensional explanation is not sufficient to cover all cases. Therefore, the assessment of eye movements in nonreading non-cognitive tasks offers a valuable approach to understand the interplay between phonological and visual theories (Jafarlou et al., 2021; Vikesdal et al., 2021).\u0026nbsp;Our results show that DD has an independent visuomotor component in addition to phonological deficit, suggesting the need to update theoretical models accordingly. Our results are largely consistent with magnocellular theory. Magnocellular theory suggests that individuals with dyslexia have difficulty processing visual stimuli, especially moving visual stimuli, and that this negatively affects the control of eye movements during reading (Stein, 2019).\u0026nbsp;In our study, we found a slowing and delay in saccades in response to moving light targets in DD, suggesting that processing of fast visual motion information is disrupted. Such a reduction in visual motion sensitivity is precisely the outcome predicted by magnocellular/dorsal pathway dysfunction. The concept of oculomotor dysfunction is actually a symptom description and is discussed as a fundamental cause or consequence in dyslexia (Bucci et al., 2012; Ibrahimi et al., 2024; Salem et al., 2022). Virlet et al. (2024) emphasized that posture, balance and coordination skills should also be targeted in interventions for children with dyslexia, drawing attention to the sensorimotor and proprioceptive basis of reading difficulties (Virlet et al., 2024) .\u0026nbsp;The cerebellar theory, another explanation of dyslexia, suggests that reading difficulties are caused by problems in the automaticity acquisition phase and that mild motor-coordination disorders in the cerebellum are reflected in language processing. According to this theory, even small-scale motor skills such as precise timing of eye movements may be impaired in individuals with dyslexia (Nicolson et al., 2001) .\u0026nbsp;In our study, differences were found in oculomotor functions in DD compared to controls. The origin of this dysfunction may be a dysfunction in the magnocellular system, cerebellar timing mechanisms or attention systems. Importantly, our findings suggest that DD is not only a phonological disorder but may also have sensorimotor aspects.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAlthough the diagnosis in our study was based on the phonological theory, the results of our study strongly overlap with the oculomotor deviations, magnocellular visual pathway theory, confirm the concept of oculomotor dysfunction, and provide limited and indirect support for components such as cerebellar theory, vestibular system and general sensory integration disorders. This multifaceted picture is in line with the multiple deficit model suggesting that dyslexia cannot be reduced to a single cause and is the result of atypical development of multiple nervous systems (Bonifacci et al., 2023).\u0026nbsp;Indeed, current views emphasize that in addition to phonological processing difficulties, disruptions in a number of cognitive processes such as visual perception, attention, auditory memory, etc. may together constitute developmental learning disabilities (Odegard et al., 2024) .\u003c/p\u003e\n\u003cp\u003eThere are some limitations that should be taken into consideration when interpreting the findings of our study. First, our sample size is relatively small and limited to applicants from a single center. Therefore, the generalizability of our findings may be limited. Second, participants\u0026apos; visual acuity and eye health were not assessed by a detailed clinical examination. Although the families were informed that the children had no known visual problems before inclusion in the study and the possibility of severe visual impairment was considered low since they were school-going children, a standard ophthalmologic examination was not performed. Although it has been reported in the literature that there is generally no significant difference in the basic visual functioning of children with dyslexia (Ibrahimi et al., 2024),\u0026nbsp;we did not directly control for this factor in our study. Third, our study has a cross-sectional design. This means that we cannot definitively answer the question of whether eye movement differences are a cause or a consequence of dyslexia. They could be an early disorder that predisposes to the emergence of DD; on the contrary, they could be an adaptive deficit that develops later in individuals who do not read sufficiently due to dyslexia. In order to draw strong causal inferences, future longitudinal studies should be conducted to monitor eye movement skills in at-risk children before they reach school age and to assess whether they are present before they start learning to read. Finally, we were not able to collect confirmatory data on the neurobiological mechanisms underlying some of the parameters we measured. For example, we were not able to correlate why the right eye OKR response was weak with structural/functional imaging in the brain. Similarly, we could not completely isolate the effect of attention levels and motivation of children with dyslexia on task performance; although our test protocol was short and non-monotonous, individual differences may have added some noise to the measurements. These issues could be further explored in the future with neuroimaging-guided eye-tracking or designs that separately measure attention-motivation variables.\u003c/p\u003e\n\u003cp\u003eDespite these limitations, our study has several carefully planned strengths and offers important contributions to the literature. First, the children with dyslexia in our study were clinically diagnosed cases and the sample selection was meticulous. Additional diagnoses such as ADHD, visual impairment and intellectual disability, which can often accompany dyslexia, were excluded from the study. Thus, we tried to ensure that the eye movement differences we obtained were as specifically related to dyslexia as possible. In this respect, our design provides a cleaner sample and can isolate dyslexia-specific features. Second, the assessments were performed with objective VNG and quantitative parameters such as saccadic rate, latency, accuracy, OKR were measured with precision. These measurements, which are not based on human observation or subjective scoring, increase the reliability of our results. Third, while our use of a non-reading task protocol can be considered a limitation, it also has some advantages and should be considered as a strength of the study. Since many studies have examined eye movements during reading or with linguistic stimuli, it remains controversial whether the differences obtained are a reflection of difficulty in reading or an underlying disorder. Finally, our study contributed to a holistic profile of the oculomotor system in dyslexia by including OKR, a component that has been relatively little studied in the literature. In particular, the lateralized OKR difference we found may lead to new research questions by pointing to a neurological difference that has not received much attention before. In all these aspects, our study is powerful research that both contributes to theoretical knowledge and may have practical outcomes. The objective findings we obtained have the potential to be used in dyslexia screening and diagnosis processes in the future and may also provide valuable information to monitor the effectiveness of interventions aimed at eliminating reading difficulties. Thus, we provide data supporting the importance of a multidimensional intervention approach to dyslexia (focusing not only on phonological training but also on visual-motor skills).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval and Informed Consent:\u0026nbsp;\u003c/strong\u003eThis study was approved by the Clinical Research Ethics Committee of Gulhane Training and Research Hospital (Date: 12.10.2022, Decision No: 2022/135). Written informed consent was obtained from the parents of all participating children.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u003c/strong\u003e MSU, MD, CK and SB contributed to the conceptualization and design of the study. MSU and CK performed data collection and VNG measurements and performed statistical analyses. MD interpreted the results and wrote the manuscript. All authors contributed to the writing of the manuscript, reviewed drafts and approved the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest:\u003c/strong\u003e The authors declare that there is no conflict of interest related to this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eNo specific external funding or funding support was received for this research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Sharing:\u003c/strong\u003e The data used in the study may be shared by the responsible author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAdi, N. S., Othman, A., Kuay, H. S., \u0026amp; Mustafa, Q. M. (2024). A study on the psychological functioning of children with specific learning difficulties and typically developing children. \u003cem\u003e12BMC Psychology\u003c/em\u003e, (1). https://doi.org/10.1186/s40359-024-02151-4\u003c/li\u003e\n \u003cli\u003eAshburn, S. M., Flowers, D. L., Napoliello, E. M., \u0026amp; Eden, G. F. (2020). Cerebellar function in children with and without dyslexia during single word processing. \u003cem\u003e41Human Brain Mapping\u003c/em\u003e, (1), 120-138. https://doi.org/10.1002/hbm.24792\u003c/li\u003e\n \u003cli\u003eAshidiqi, A. S., Widaningrum, I., \u0026amp; Karaman, J. (2023). Implementation of The Certainty Factor Method in The Expert System For Early Diagnosis of Dyslexia in Childhood. \u003cem\u003eINTENSIF: 7Jurnal Ilmiah Penelitian Dan Penerapan Teknologi Sistem Informasi\u003c/em\u003e, (1), 18-32. https://doi.org/10.29407/intensif.v7i1.18433\u003c/li\u003e\n \u003cli\u003eBilbao, C., Carrera, A., Otin, S., \u0026amp; Pi\u0026ntilde;ero, D. P. (2024). Eye Tracking-Based Characterization of Fixations during Reading in Children with Neurodevelopmental Disorders. \u003cem\u003e14Brain Sciences\u003c/em\u003e, (8). https://doi.org/10.3390/brainsci14080750\u003c/li\u003e\n \u003cli\u003eBlythe, H. I., Kirkby, J. A., \u0026amp; Liversedge, S. P. (2018). Comments on: \u0026quot;what is developmental dyslexia?\u0026quot; brain sci. 2018, 8, 26. the relationship between eye movements and reading difficulties. \u003cem\u003e8Brain Sciences\u003c/em\u003e, (6). https://doi.org/10.3390/brainsci8060100\u003c/li\u003e\n \u003cli\u003eBonifacci, P., Tobia, V., Sansavini, A., \u0026amp; Guarini, A. (2023). Eye-Movements in a Text Reading Task: A Comparison of Preterm Children, Children with Dyslexia and Typical Readers. \u003cem\u003e13Brain Sciences\u003c/em\u003e, (3). https://doi.org/10.3390/brainsci13030425\u003c/li\u003e\n \u003cli\u003eBucci, M. P. (2021). Visual training could be useful for improving reading capabilities in dyslexia. \u003cem\u003e10Applied Neuropsychology: Child\u003c/em\u003e, (3), 199-208. https://doi.org/10.1080/21622965.2019.1646649\u003c/li\u003e\n \u003cli\u003eBucci, M. P., Nassibi, N., Gerard, C. L., Bui-Quoc, E., \u0026amp; Seassau, M. (2012). Immaturity of the oculomotor saccade and vergence interaction in dyslexic children: Evidence from a reading and visual search study. \u003cem\u003e7PLoS ONE\u003c/em\u003e, (3), 1-8. https://doi.org/10.1371/journal.pone.0033458\u003c/li\u003e\n \u003cli\u003eCaldani, S., Gerard, C. L., Peyre, H., \u0026amp; Bucci, M. P. (2020). Visual attentional training improves reading capabilities in children with dyslexia: An eye tracker study during a reading task. \u003cem\u003e10Brain Sciences\u003c/em\u003e, (8), 1-13. https://doi.org/10.3390/brainsci10080558\u003c/li\u003e\n \u003cli\u003eCeple, I., Krauze, L., Serpa, E., Svede, A., Goliskina, V., Vasiljeva, S., Kassaliete, E., Ganebnaya, A., Volberga, L., Truksa, R., Ruza, T., \u0026amp; Krumina, G. (2025). Eye Movement Parameters in Children with Reading Difficulties. \u003cem\u003e15Applied Sciences (Switzerland)\u003c/em\u003e, (2). https://doi.org/10.3390/app15020954\u003c/li\u003e\n \u003cli\u003eChi, J., Reed, D. K., \u0026amp; Mcbride, C. (2025). The effects of orthography , phonology , semantics , and working memory on the reading comprehension of children with and without reading dyslexia. \u003cem\u003e0123456789Annals of Dyslexia\u003c/em\u003e, . https://doi.org/10.1007/s11881-025-00322-5\u003c/li\u003e\n \u003cli\u003eCoenen, L., Gr\u0026uuml;nke, M., Becker-Genschow, S., Schl\u0026uuml;ter, K., Schulden, M., \u0026amp; Barwasser, A. (2024). A Systematic Review of Eye-Tracking Technology in Dyslexia Diagnosis. \u003cem\u003e21Insights into Learning Disabilities\u003c/em\u003e, (1), 45-65. www.ldworldwide.org.\u003c/li\u003e\n \u003cli\u003eDalvand, H., Chamani, N., Rahsepar-Fard, K., Khorrami-Nejad, M., \u0026amp; Dadgar, H. (2023). The effect of online visual games on visual perception, oculomotor, and balance skills of children with developmental dyslexia during the COVID-19 pandemic. \u003cem\u003e43International Ophthalmology\u003c/em\u003e, (12), 5011-5024. https://doi.org/10.1007/s10792-023-02904-x\u003c/li\u003e\n \u003cli\u003eDemir, İ., Cengiz, D. U., Demir, A. \u0026Ccedil;., \u0026Ccedil;olak, S. C., Birişik, S. D., \u0026amp; \u0026Ouml;zcan, \u0026Ouml;. \u0026Ouml;. (2023). Vestibular Evaluation of Children Diagnosed with Specific Learning Disorder. \u003cem\u003eAlpha Psychiatry\u003c/em\u003e, \u003cem\u003e24\u003c/em\u003e(5), 211.\u003c/li\u003e\n \u003cli\u003eDoettl, S. M., \u0026amp; McCaslin, D. L. (2018). Oculomotor Assessment in Children. \u003cem\u003e39Seminars in Hearing\u003c/em\u003e, (3), 275-287. https://doi.org/10.1055/s-0038-1666818\u003c/li\u003e\n \u003cli\u003eDoettl, S. M., Plyler, P. N., McCaslin, D. L., \u0026amp; Schay, N. L. (2015). Pediatric oculomotor findings during monocular videonystagmography: A developmental study. \u003cem\u003e26Journal of the American Academy of Audiology\u003c/em\u003e, (8), 703-715. https://doi.org/10.3766/jaaa.14089\u003c/li\u003e\n \u003cli\u003eEden, G. F., Stein, J. F., Wood, H. M., \u0026amp; Wood, F. B. (1994). Differences in eye movements and reading problems in dyslexic and normal children. \u003cem\u003e34Vision Research\u003c/em\u003e, (10), 1345-1358. https://doi.org/10.1016/0042-6989(94)90209-7\u003c/li\u003e\n \u003cli\u003eEl Hmimdi, A. E., Ward, L. M., Palpanas, T., \u0026amp; Kapoula, Z. (2021). Predicting dyslexia and reading speed in adolescents from eye movements in reading and non-reading tasks: A machine learning approach.\u0026nbsp;\u003cem\u003e11Brain Sciences\u003c/em\u003e, (10). https://doi.org/10.3390/brainsci11101337\u003c/li\u003e\n \u003cli\u003eFella, A., Loizou, M., Christoforou, C., \u0026amp; Papadopoulos, T. C. (2023). Eye Movement Evidence for Simultaneous Cognitive Processing in Reading. \u003cem\u003e10Children\u003c/em\u003e, (12), 1-17. https://doi.org/10.3390/children10121855\u003c/li\u003e\n \u003cli\u003eG\u0026ouml;rker, I., Bozatli, L., Korkmazlar, \u0026Uuml;., Y\u0026uuml;cel Karadag, M., Ceylan, C., S\u0026ouml;ğ\u0026uuml;t, C., Aykutlu, H. C., Subay, B., \u0026amp; Turan, N. (2017). The probable prevalence and sociodemographic characteristics of specific learning disorder in primary school children in edirne. \u003cem\u003e54Noropsychiatry Archives\u003c/em\u003e, (4), 343-349. https://doi.org/10.5152/npa.2016.18054\u003c/li\u003e\n \u003cli\u003eGranet, D. B. (2011). Learning disabilities, dyslexia, and vision: The role of the pediatric ophthalmologist. \u003cem\u003e15Journal of AAPOS\u003c/em\u003e, (2), 119-120. https://doi.org/10.1016/j.jaapos.2011.03.003\u003c/li\u003e\n \u003cli\u003eGrigorenko, E. L., Fuchs, L. S., Willcutt, E. G., Compton, D. L., Wagner, R. K., \u0026amp; Fletcher, J. M. (2020). Understanding, Educating, and Supporting Children With Specific Learning Disabilities: 50 Years of Science and Practice.\u0026nbsp;\u003cem\u003e75American Psychologist\u003c/em\u003e, (1), 37-51. https://doi.org/10.1037/amp0000452\u003c/li\u003e\n \u003cli\u003eIbrahimi, D., Aviles, M., \u0026amp; Rodr\u0026iacute;guez-Res\u0026eacute;ndiz, J. (2024). Oculomotor Patterns in Children with Poor Reading Abilities Measured Using the Development Eye Movement Test. \u003cem\u003e13Journal of Clinical Medicine\u003c/em\u003e, (15). https://doi.org/10.3390/jcm13154415\u003c/li\u003e\n \u003cli\u003eJafarlou, F., Ahadi, M., \u0026amp; Jarollahi, F. (2021). Eye movement patterns in Iranian dyslexic children compared to non-dyslexic children.\u0026nbsp;\u003cem\u003e48Auris Nasus Larynx\u003c/em\u003e, (4), 594-600. https://doi.org/10.1016/j.anl.2020.11.012\u003c/li\u003e\n \u003cli\u003eJothi Prabha, A., \u0026amp; Bhargavi, R. (2020). Predictive Model for Dyslexia from Fixations and Saccadic Eye Movement Events. \u003cem\u003e195Computer Methods and Programs in Biomedicine\u003c/em\u003e, . https://doi.org/10.1016/j.cmpb.2020.105538\u003c/li\u003e\n \u003cli\u003eMacambira, Y. K. dos S., Barbosa, J. V. dos S., Queiroga, B. M. de, Cordeiro, A. A. de A., Menezes, D. C., Lima, M. L. L. T. de, \u0026amp; Adv\u0026iacute;ncula, K. P. (2022). Ocular findings from otoneurological examinations in children with and without dyslexia: a systematic review with meta-analysis. \u003cem\u003e88Brazilian Journal of Otorhinolaryngology\u003c/em\u003e, , S192-S201. https://doi.org/10.1016/j.bjorl.2021.10.006\u003c/li\u003e\n \u003cli\u003eMiladinović, A., Quaia, C., Ajčević, M., Diplotti, L., Cumming, B. G., Pensiero, S., \u0026amp; Accardo, A. (2022). Ocular-following responses in school-age children. \u003cem\u003e17PLoS ONE\u003c/em\u003e, (November 11), 1-15. https://doi.org/10.1371/journal.pone.0277443\u003c/li\u003e\n \u003cli\u003eNas \u0026Ouml;z\u0026uuml;temiz, G., A\u0026ccedil;ıks\u0026ouml;z Yay, Ş. \u0026Ouml;., \u0026Ouml;z, I., Akın Sarı, B., Ayraler Taner, H., \u0026amp; \u0026Ccedil;akmak, E. (2025). The effect of dynamic visual acuity on rapid naming in school-aged children with dyslexia. \u003cem\u003e190International Journal of Pediatric Otorhinolaryngology\u003c/em\u003e, (January). https://doi.org/10.1016/j.ijporl.2025.112253\u003c/li\u003e\n \u003cli\u003eNatrayan, R., \u0026amp; Chauhan, A. K. (2025). Exploring the role of the vestibular system in visuospatial memory in developmental dyslexia: \u003cem\u003e58\u003c/em\u003eNarrative review. \u003cem\u003eJournal of Associated Medical Sciences\u003c/em\u003e, (1), 177-184. https://doi.org/10.12982/JAMS.2025.019\u003c/li\u003e\n \u003cli\u003eNeru\u0026scaron;il, B., Polec, J., \u0026Scaron;kunda, J., \u0026amp; Kačur, J. (2021). Eye tracking based dyslexia detection using a holistic approach.\u0026nbsp;\u003cem\u003e11Scientific Reports\u003c/em\u003e, (1), 1-10. https://doi.org/10.1038/s41598-021-95275-1\u003c/li\u003e\n \u003cli\u003eNguyen, T. K. C., Le, D. D., Le, T. H., Nguyen, T. C. H., \u0026amp; Ngo, T. D. (2024).\u0026nbsp;\u003cem\u003e0\u003c/em\u003eThe use of eye tracking in supporting individuals with dyslexia: a review. \u003cem\u003eDisability and Rehabilitation: Assistive Technology\u003c/em\u003e, (0), 1-16. https://doi.org/10.1080/17483107.2024.2437697\u003c/li\u003e\n \u003cli\u003eNicolson, R. I., Fawcett, A. J., \u0026amp; Dean, P. (2001). Developmental dyslexia: The cerebellar deficit hypothesis. \u003cem\u003e24Trends in Neurosciences\u003c/em\u003e, (9), 508-511. https://doi.org/10.1016/S0166-2236(00)01896-8\u003c/li\u003e\n \u003cli\u003eOdegard, T. N., Farris, E. A., \u0026amp; Middleton, A. E. (2024). Dyslexia in the 21st century: revisiting the consensus definition. \u003cem\u003eAnnals of Dyslexia\u003c/em\u003e, 273-281. https://doi.org/10.1007/s11881-024-00316-9\u003c/li\u003e\n \u003cli\u003e\u0026Ouml;l\u0026ccedil;ek, G., \u0026Ccedil;elik, İ., Başoǧlu, Y., Kaymak\u0026ccedil;ı, S., \u0026amp; G\u0026uuml;rlek, E. (2023). Comparison of children with and without dyslexia using functional head impulse test and pediatric balance scale. \u003cem\u003e14Frontiers in Neurology\u003c/em\u003e, . https://doi.org/10.3389/fneur.2023.1153650\u003c/li\u003e\n \u003cli\u003ePavlidis, G. T. (1981). Do eye movements hold the key to dyslexia?\u0026nbsp;\u003cem\u003e19Neuropsychologia\u003c/em\u003e, (1), 57-64. https://doi.org/10.1016/0028-3932(81)90044-0\u003c/li\u003e\n \u003cli\u003ePensiero, S., Accardo, A., Michieletto, P., \u0026amp; Brambilla, P. (2013). Saccadic Alterations in Severe Developmental Dyslexia. \u003cem\u003e2013Case Reports in Neurological Medicine\u003c/em\u003e, , 1-5. https://doi.org/10.1155/2013/406861\u003c/li\u003e\n \u003cli\u003ePicciotti, P. M., Mele, D. A., Settimi, S., Mari, G., D\u0026apos;Alatri, L., \u0026amp; Galli, J. (2024). Subjective visual vertical/horizontal and video head impulse test in dyslexic children. \u003cem\u003e30Dyslexia\u003c/em\u003e, (4), 1-12. https://doi.org/10.1002/dys.1782\u003c/li\u003e\n \u003cli\u003ePiko, B. F., \u0026amp; Dudok, R. (2023). Strengths and Difficulties among Adolescent with and without Specific Learning Disorders (SLD). \u003cem\u003e10Children\u003c/em\u003e, (11), 1-14. https://doi.org/10.3390/children10111741\u003c/li\u003e\n \u003cli\u003eProtasevica, D., Kassaliete, E., Klavinska, A., Alecka, M., Berzina, A., Goliskina, V., Koleda, M., Mikelsone, R., Ozola, E., Ruza, T., Serpa, E., Svede, A., Toloka, D., Vasiljeva, S., Volberga, L., Ceple, I., \u0026amp; Krumina, G. (2024). The Computerized Developmental Eye Movement (DEM) Test: Normative Data for School-Aged Children.\u0026nbsp;\u003cem\u003e8Vision\u003c/em\u003e, (3), 47. https://doi.org/10.3390/vision8030047\u003c/li\u003e\n \u003cli\u003eRodr\u0026iacute;guez, K., Fonseca, L., Iaconis, F.-R., Del-Punta, J., \u0026amp; Gasaneo, G. (2025). Eye tracking studies, a way to understand difficulties in reading processing. \u003cem\u003e24Ocnos\u003c/em\u003e, (1). https://doi.org/10.18239/ocnos_2025.24.1.488\u003c/li\u003e\n \u003cli\u003eSalem, T., Elsherif, M., Mourad, M., Abdou, R., \u0026amp; Hamouda, N. (2022). Eye movements and visual perception in dyslexic children. \u003cem\u003e20Hearing, Balance and Communication\u003c/em\u003e, (2), 109-119. https://doi.org/10.1080/21695717.2022.2028496\u003c/li\u003e\n \u003cli\u003eSeassau, M., G\u0026eacute;rard, C. L., Bui-Quoc, E., \u0026amp; Bucci, M. P. (2014). Binocular saccade coordination in reading and visual search: A developmental study in typical reader and dyslexic children. \u003cem\u003e8Frontiers in Integrative Neuroscience\u003c/em\u003e, (October), 1-11. https://doi.org/10.3389/fnint.2014.00085\u003c/li\u003e\n \u003cli\u003eSinno, S., Najem, F., Abouchacra, K. S., Perrin, P., \u0026amp; Dumas, G. (2020). Normative Values of Saccades and Smooth Pursuit in Children Aged 5 to 17 Years. \u003cem\u003e31Journal of the American Academy of Audiology\u003c/em\u003e, (6), 384-392. https://doi.org/10.3766/jaaa.19049\u003c/li\u003e\n \u003cli\u003eSnowling, M. J., Hulme, C., \u0026amp; Nation, K. (2020). Defining and understanding dyslexia: past, present and future. \u003cem\u003e46Oxford Review of Education\u003c/em\u003e, (4), 501-513. https://doi.org/10.1080/03054985.2020.1765756\u003c/li\u003e\n \u003cli\u003eStein, J. (2019). The current status of the magnocellular theory of developmental dyslexia. \u003cem\u003e130Neuropsychologia\u003c/em\u003e, (September 2017), 66-77. https://doi.org/10.1016/j.neuropsychologia.2018.03.022\u003c/li\u003e\n \u003cli\u003eStein, J. (2023). Theories about Developmental Dyslexia.\u0026nbsp;\u003cem\u003e13Brain Sciences\u003c/em\u003e, (2). https://doi.org/10.3390/brainsci13020208\u003c/li\u003e\n \u003cli\u003eStella, M., \u0026amp; Engelhardt, P. E. (2021). Comprehension and eye movements in the processing of subject-and object-relative clauses: Evidence from dyslexia and individual differences\u0026dagger;.\u0026nbsp;\u003cem\u003e11Brain Sciences\u003c/em\u003e, (7). https://doi.org/10.3390/brainsci11070915\u003c/li\u003e\n \u003cli\u003eSvaricek, R., Dostalova, N., Sedmidubsky, J., \u0026amp; Cernek, A. (2025). INSIGHT: Combining Fixation Visualizations and Residual Neural Networks for Dyslexia Classification From Eye-Tracking Data. \u003cem\u003e31Dyslexia\u003c/em\u003e, (1), 1-14. https://doi.org/10.1002/dys.1801\u003c/li\u003e\n \u003cli\u003eTiadi, A., Seassau, M., Bui-Quoc, E., Gerard, C. L., \u0026amp; Bucci, M. P. (2014). Vertical saccades in dyslexic children. \u003cem\u003e35Research in Developmental Disabilities\u003c/em\u003e, (11), 3175-3181. https://doi.org/10.1016/j.ridd.2014.07.057\u003c/li\u003e\n \u003cli\u003eTobener, E., Searer, A., Doettl, S., \u0026amp; Plyler, P. (2024). Oculomotor Findings in Videonystagmography across the Lifespan. In \u003cem\u003eJournal of the American Academy of Audiology.\u0026nbsp;\u003c/em\u003ehttps://doi.org/10.1055/s-0042-1760437\u003c/li\u003e\n \u003cli\u003eToki, E. I. (2024). Using Eye-Tracking to Assess Dyslexia: A Systematic Review of Emerging Evidence. \u003cem\u003e14Education Sciences\u003c/em\u003e, (11). https://doi.org/10.3390/educsci14111256\u003c/li\u003e\n \u003cli\u003eTrauzettel-Klosinski, S., Koitzsch, A. M., D\u0026uuml;rrw\u0026auml;chter, U., Sokolov, A. N., Reinhard, J., \u0026amp; Klosinski, G. (2010). \u003cem\u003e88\u003c/em\u003eEye movements in German-speaking children with and without dyslexia when reading aloud\u003cem\u003e. Acta Ophthalmologica\u003c/em\u003e, (6), 681-691. https://doi.org/10.1111/j.1755-3768.2009.01523.x\u003c/li\u003e\n \u003cli\u003e\u0026Uuml;nal, F., \u0026Ouml;ktem, F., \u0026Ccedil;uhadaroğlu, F. \u0026Ccedil;., K\u0026uuml;lt\u0026uuml;r, S. E. \u0026Ccedil;., Akdemİr, D., \u0026Ouml;zdemİr, D. F., \u0026Ccedil;ak, H. T., \u0026Uuml;nal, D., Tiraş, K., Aslan, C., \u0026amp; Kalayci, B. M. (2019). Validity and Reliability of the Turkish Adaptation of the Affective Disorders and Schizophrenia Interview Schedule for School Age Children - Now and Lifetime Form - DSM - 5 November 2016 - Turkish Adaptation (\u0026Ccedil;DŞG - ŞY - DSM - 5 - T). \u003cem\u003eTurkish Journal of Psychiatry\u003c/em\u003e, \u003cem\u003e30\u003c/em\u003e(1), 42\u0026ndash;50.\u003c/li\u003e\n \u003cli\u003eVagge, A., Cavanna, M., Traverso, C. E., \u0026amp; Iester, M. (2015). Evaluation of ocular movements in patients with dyslexia. \u003cem\u003e65Annals of Dyslexia\u003c/em\u003e, (1), 24-32. https://doi.org/10.1007/s11881-015-0098-7\u003c/li\u003e\n \u003cli\u003eVaitheeshwari, R., Chih-Hsuan, C., Chung, C. R., Yang, H. Y., Yeh, S. C., Wu, E. H. K., \u0026amp; Kumar, M. (2024). Dyslexia Analysis and Diagnosis Based on Eye Movement. \u003cem\u003e32IEEE Transactions on Neural Systems and Rehabilitation Engineering\u003c/em\u003e, , 4109-4119. https://doi.org/10.1109/TNSRE.2024.3496087\u003c/li\u003e\n \u003cli\u003eVikesdal, G. H., Falkenberg, H. K., Mon-Williams, M., Riddell, P., \u0026amp; Langaas, T. (2021). Normal saccades but decreased fixation stability in a population of children with dyslexia. \u003cem\u003e14\u003c/em\u003e(2), 1\u0026ndash;7. \u003cem\u003eScandinavian Journal of Optometry and Visual Science\u003c/em\u003e, https://doi.org/10.5384/sjovs.v14i2.137\u003c/li\u003e\n \u003cli\u003eVinuela-Navarro, V., Erichsen, J. T., Williams, C., \u0026amp; Woodhouse, J. M. (2017). Saccades and fixations in children with delayed reading skills. \u003cem\u003e37Ophthalmic and Physiological Optics\u003c/em\u003e, (4), 531-541. https://doi.org/10.1111/opo.12392\u003c/li\u003e\n \u003cli\u003eVirlet, L., Sparrow, L., Barela, J., Berquin, P., \u0026amp; Bonnet, C. (2024). Proprioceptive intervention improves reading performance in developmental dyslexia: An eye-tracking study. \u003cem\u003e153Research in Developmental Disabilities\u003c/em\u003e, (October 2023), 104813. https://doi.org/10.1016/j.ridd.2024.104813\u003c/li\u003e\n \u003cli\u003eWang, H., Liu, F., Dong, Y., \u0026amp; Yu, D. (2022). Entropy of eye movement during rapid automatized naming. \u003cem\u003e16Frontiers in Human Neuroscience\u003c/em\u003e, (August), 1-12. https://doi.org/10.3389/fnhum.2022.945406\u003c/li\u003e\n \u003cli\u003eWU, Y. J., YANG, W. H., WANG, Q. X., YANG, D. S., HU, X. Y., JING, J., \u0026amp; LI, X. H. (2018). Eye-movement Patterns of Chinese Children with Developmental Dyslexia during the Stroop Test. \u003cem\u003e31Biomedical and Environmental Sciences\u003c/em\u003e, (9), 677-685. https://doi.org/10.3967/bes2018.092\u003c/li\u003e\n \u003cli\u003eXia, Z., Hoeft, F., Zhang, L., \u0026amp; Shu, H. (2016). Neuroanatomical anomalies of dyslexia: Disambiguating the effects of disorder, performance, and maturation.\u0026nbsp;\u003cem\u003e81Neuropsychologia\u003c/em\u003e, , 68-78. https://doi.org/10.1016/j.neuropsychologia.2015.12.003\u003c/li\u003e\n \u003cli\u003eYang, L. P., Li, C. B., Li, X. M., Zhai, M. M., Zhao, J., \u0026amp; Weng, X. C. (2022). Prevalence of developmental dyslexia in primary school children: a protocol for systematic review and meta-analysis. \u003cem\u003e18World Journal of Pediatrics\u003c/em\u003e, (12), 804-809. https://doi.org/10.1007/s12519-022-00572-y\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 2 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Dyslexia, Eye movement, Eye tracking, Learning disabilities, Reading disability, Oculomotor, Saccades","lastPublishedDoi":"10.21203/rs.3.rs-6526788/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6526788/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSpecific learning disorder (SLD) is a neurodevelopmental disorder characterized by difficulties in reading, writing and math skills. Saccadic eye movements play a critical role in fluent reading and visual scanning. 40 children with dyslexia and 40 healthy controls were included in this study according to DSM-5 criteria, since children with dyslexia have reading fluency disorders and saccadic eye movements are necessary for fluent reading. Psychiatric evaluations and structured clinical interviews were conducted by an experienced child and adolescent psychiatrist. Saccadic eye movements (saccadic velocity, accuracy and latency) were recorded using a videonystagmography (VNG) system and compared between the two groups. Results showed that children with dyslexia exhibited significantly lower saccadic velocity (307.5\u0026deg;/s vs. 453.5\u0026deg;/s, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and saccadic accuracy (71.5% vs. 98.5%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and significantly longer saccadic latency (260.0 ms vs. 131.5 ms, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Optokinetic responses in the right eye were significantly less in the SLD group (p\u0026thinsp;=\u0026thinsp;0.028), whereas no significant difference was observed in the left eye responses (p\u0026thinsp;=\u0026thinsp;0.067). These findings suggest that children with dyslexia have significant oculomotor dysfunction independent of the act of reading. This may contribute to reading difficulties and impaired visual information processing, and oculomotor assessment in dyslexia may be a useful tool in the development of etiologic diagnosis and interventions.\u003c/p\u003e","manuscriptTitle":"Oculomotor Dysfunctions in Non-Reading Tasks in Children with Developmental Dyslexia: Saccadic and Optokinetic Findings","msid":"","msnumber":"","nonDraftVersions":[{"code":2,"date":"2025-05-14 14:22:13","doi":"10.21203/rs.3.rs-6526788/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2025-04-28 07:52:58","doi":"10.21203/rs.3.rs-6526788/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8bed7a36-b039-44e4-8391-3dab6d5517cd","owner":[],"postedDate":"May 14th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":48216412,"name":"Psychiatry"},{"id":48216413,"name":"Otorhinolaryngology"},{"id":48216414,"name":"Psychology"}],"tags":[],"updatedAt":"2025-04-28T07:52:58+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-14 14:22:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v2","identity":"rs-6526788","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6526788","identity":"rs-6526788","version":["v2"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}