# Eye Movement Parameters in Children with Reading Difficulties
## 4 Discussion
Data analysis revealed a significant age effect on the smooth pursuit performance which was independent of reading performance, likely due to improvements in binocular coordination, saccade latency, and coordination between saccadic and vergence movements, which continue to develop until 12 to 15 years of age [63]. More recent studies by [PERSON] et al. [56] and [PERSON] et al. [32] have demonstrated that dyslexic children generally exhibit decreased smooth pursuit gain, especially in the left-to-right direction [30]. They also tend to make more catch-up saccades [42]. So what causes the inconsistency with the results of the current research, as well as the results presented by [PERSON] et al. [39] and [PERSON] et al. [61]? While all of the previously mentioned studies have explored smooth pursuit performance in children with dyslexia, a different methodology of participant selection can be observed. The criteria for diagnosing dyslexia vary widely, with some studies using broader definitions or different reading-related tests, which could influence group characteristics and outcomes. The prevalence of developmental dyslexia is estimated around 7% [64], while the prevalence of reading difficulties in the current research was around 25%, including both children with dyslexia and children with reading difficulties caused by other factors (social, environmental, etc.). The results of the current study propose that the smooth pursuit control in children with reading difficulties is intact, and that observed differences in smooth pursuit performance in children with dyslexia might be attributed to magnocellular dysfunction, attention deficits, or other factors previously linked to dyslexia [65]. One of the parameters that characterizes the fixation quality is its stability, i.e., the ability to keep a steady gaze on the fixation target. To assess whether the fixation stability is impaired in children with reading difficulties, fixation stability was assessed in a non-reading task, thereby reducing the involvement of cognitive processes on the eye movement performance. A similar approach of analyzing binocular fixation quality in children with and without reading difficulties was applied by [PERSON] et al. [38], exploring the number and amplitude of saccadic eye movements during fixation. Both the current study and the study by [PERSON] et al. [38] did not reveal significant differences in fixation stability in children with and without reading difficulties. The results of our study, however, contradict the findings by [PERSON] et al. [66], demonstrating that children with dyslexia have more unstable fixation in non-reading tasks than children without dyslexia. Although dyslexia is a specific learning disorder of neurobiological origin that primarily affects reading, as mentioned before, the children included in our study had reading difficulties but were not diagnosed with dyslexia, which could explain why the results contradict those of [PERSON] et al. [66]. The dynamics of saccadic and smooth pursuit eye movements are also characterized by other parameters, e.g., latency and initial acceleration; however, latency was not considered in the current study, since prior research and methodological constraints have indicated that latency may not reliably reflect oculomotor performance differences in children with and without reading difficulties. For example, [PERSON] et al. [39] and [PERSON] et al. [38] found no significant differences in saccadic latency between dyslexic and non-dyslexic children, suggesting that latency might not be a robust marker for reading difficulties. Moreover, latency measurements are often influenced by external factors, such as age-related variability in neural development and task complexity, which could introduce noise rather than providing insight into the specific oculomotor mechanisms linked to reading performance.