Gait kinematics during walking in children with amblyopia

Abstract

Introduction: Coordination between the eyes and body is important for navigating the environment. Children with amblyopia score lower for walking on standardized tests of motor ability. However, standardized tests do not assess gait kinematics during walking. Here, I investigated the development of gait kinematics during walking under natural binocular viewing conditions in children with amblyopia compared to controls. Methods: A total of 21 children ages 7 to 13 years with amblyogenic factors (14 anisometropia, 7 strabismus) were enrolled in the ‘amblyopia’ group (15∕21 had current amblyopia). An age-similar group of 27 controls were also enrolled. While viewing binocularly, children walked the length of a GAITRite pressure-sensitive walkway and completed 3 conditions of varying complexity: 1) Straight Walk (SW): walk on mat, 2) Isolated Target Walk (IT): walk and step on two-dimensional targets, and 3) Distractor Target Walk (DT): walk and step on two-dimensional targets while avoiding two-dimensional distractors. Gait kinematics were temporal outcomes of normalized velocity (leg lengths/second), cadence (spm), step time (msecs), and stance time, and spatial outcomes of (msecs), step length (cm), step width (cm) and accuracy (%) of stepping on targets or avoiding distractors. Variability in gait kinematics was also examined using the coefficient of variation (COV, %). Results: Temporal and spatial outcomes of gait kinematics did not differ between children with amblyopia and controls. However, the amblyopia group was less accurate at stepping on targets overall than controls (amblyopia, mean±SD=90.8±8.5% vs control, 96.9±3.8%, p=0.003), with less accuracy found in the IT condition (89.7±9.7% vs 96.5±5.3%, p=0.005), and for the far T2 target (87.4±13.9% vs 97.2±5.4%, p=0.001). Lastly, the amblyopia group showed increased variability (i.e., higher COV) for temporal measures, including normalized velocity (8.9±3.0% vs 6.4±3.0%, p=0.007), stance time (5.7±1.8% vs 4.7±1.8%, p=0.049), cadence (5.0±2.4% vs 3.3±1.7%, p=0.005) and step time (4.9±2.5% vs 3.5±2.1%, p=0.040), and for spatial measures, including step length (8.0±2.4% vs 6.4±2.4%, p=0.024) and step width (7.7±2.2% vs 6.11±2.2%, p=0.014). In the amblyopia group, spatial outcomes were correlated with amblyopic eye visual acuity and temporal measures were correlated with stereoacuity. Conclusions: This thesis shows that unbalanced visual input early in life from pediatric eye conditions that cause amblyopia results in variable and inaccurate walking patterns compared to children with age-typical visual development. This pattern of findings is similar to younger children, indicating that the typical development of gait is delayed in children with amblyopia, especially when they have poor binocularity outcomes. These findings point to the importance of typical binocular vision for the development of walking.