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Motor development in visually impaired children

According to the World Health Organisation, 285 million people worldwide suffer from a visual impairment at present (http://www.who.int/blindness/en/), with cataracts as the leading cause of blindness. Although the majority of patients are over the age of 50, about 19 million children are affected. The aim of the global eye health action plan 2014–2019 is to reduce avoidable visual impairment as a global public health problem and secure access to rehabilitation services for the visual impaired or blind. To develop adequate rehabilitation programs, knowledge of the secondary problems associated with a visual impairment is imperative. In children, a visual impairment affects their overall development, including their motor development and skill acquisition. Different studies report a delay in gross motor milestones such as head control, sitting, standing, crawling, and walking during the first year of life. Vision appears to be key to normal postural and motor development in infants. Whether, during development, multisensory integration and brain plasticity might overcome this initial delay is uncertain. When locomotion is considered, young children show adaptations in their gait pattern to allow for more stability, such as a wider base of support and a longer duration of double support but these differences tend to disappear after the age of 10. In children showing blindness, adaptations in gait are more pronounced than in those with low vision. Celano et al. investigated motor skills of children aged 4.5 years that were treated unilaterally for cataracts. Their results confirm previous findings on motor delay in visually impaired children. Mean scores on the Movement ABC test battery were low and as much as 40% of the children obtained scores at or below the 5th percentile. What is very interesting about the study is that different multicausal factors are explored in an attempt to explain why children with a unilateral aphakic eye show motor delay. Surprisingly, the age at which surgery was performed, ocular alignment, and stereopsis were not related to motor performance at age 4.5 years. The degree of delay was only related to visual acuity of the best eye. This is even more surprising since the majority of children (88%) only showed a mild visual impairment. However, only a limited amount of variance in the data was explained by the model used. Further research is warranted to better understand the causes of this motor delay in children with a unilateral aphakic eye. As the authors themselves suggest, the technique of patching is an interesting starting point. Also, longitudinal follow-up studies are necessary to investigate whether this motor delay at a young age can be overcome later in life, as is seen in studies regarding locomotion in visually impaired children. Studies should consider children at least until the age of 8 or 9 years. This is so because, in typically developing children, it has repeatedly been shown that the age of 7 is a turning point where children acquire important sensory integrating skills (primarily visual integration) that affect postural and motor control. For rehabilitation purposes it would be of key interest to find out whether this development shift also occurs in children with a visual impairment. To conclude, motor development in visually impaired children is an interesting but largely unexplored topic that warrants further attention in order to improve rehabilitation, activities, and daily life participation in this population.