Background: To determine the prevalence of amblyopia in schoolchildren aged 7–9 years old in Mashhad, Iran. Methods: This was a cross-sectional, community-based study with schoolchildren aged 7–9 years old. We randomly selected 20 of 189 elementary schools (three schools per district; 10 male-segregated and 10 female-segregated schools) from a proportional combination of public schools across Mashhad. Basic vision exams were performed. If amblyopia was suspected, children underwent supplementary vision exams. The diagnostic criterion for amblyopia was a best corrected visual acuity (BCVA) in one or both eyes equal to or worse than 20/40 or an interocular difference of more than two lines in BCVA without any significant organic pathology. Results: A total of 2831 children were included in the study. All children were examined comprehensively by an optometrist, and amblyopia was detected in 49/2831 (1.7% [95% CI, 1.22?2.18]). Of the 49 children with amblyopia, 20 (40.8%) were amblyopic in the right eye, 9 (18.4%) in the left eye, and 20 (40.8%) in both eyes. Twenty-four (49%) were first graders, 15 (30.6%) were second graders, and 10 (20.4%) were third graders. The most prevalent subtype of amblyopia was anisometropic amblyopia (57.1%, [95% CI, 43.24?70.96]). Conclusions: Considering the prevalence of amblyopia among schoolchildren aged 7–9 years old (1.7%), timely detection of amblyopia through preschool screening programs is essential for early treatment or prevention of further visual impairment during childhood. How to cite this article: Shahpary S, Ramin S, Azimi A, Heyrani M. The prevalence of amblyopia in 7-9-year-old schoolchildren in Mashhad. Med Hypothesis Discov Innov Optom.2021 Spring; 2(1): 18-23. DOI: https://doi.org/10.51329/mehdioptometry121

Purpose:This study aimed to compare pattern visual evoked potential (PVEP) components in dyslexic and normal children.Methods:This cross-sectional analytic study recruited 72 children, including 36 dyslexic and 36 normal participants aged 8-12 years. Visual examinations included measurement of distance visual acuity, refraction, and PVEP components of amplitudes and latencies with two different check sizes of 15 and 60 minutes (min) of arc at two contrast levels of 25% and 100%.Results:Our results demonstrated significant differences between dyslexic and normal children in terms of P100 latency and amplitude of PVEP at 25% contrast, with check sizes of 15 and 60 min of arc. However, there were no significant differences between the two groups regarding P100 latency and amplitude at 100% contrast with check sizes of both 15 and 60 min of arc.Conclusion:Dyslexic participants showed reduced amplitude and prolonged latency in most PVEP components at low-contrast levels. These findings may support the magnocellular deficit hypothesis in dyslexic participants, even though the parvocellular pathway remains intact.