Visual acuity and motor outcomes in very low birthweight adults: Mediation or shared aetiology?

Motor functioning represents a fundamental developmental domain that influences and is influenced by other key developmental areas, including perception, cognition, and behaviour.1 Very preterm birth or very low birthweight (VLBW) pose significant risks for altered brain development, which can lead to lasting neurodevelopmental and physical health problems.2 Given the improved survival rates of this high-risk population, understanding long-term motor outcomes has become critical. The study by Benum et al.3 uses data from two well-characterized Nordic cohort studies with harmonized assessment protocols. It addresses an important gap in the literature by examining visual acuity as a mediator in the pathway between VLBW and motor outcomes in adulthood. While previous research demonstrates that individuals born VLBW experience higher rates of both visual and motor impairments,4, 5 few studies have specifically investigated the mechanisms underlying these relationships in adulthood. These findings provide insight into developmental pathways and reinforce how visual acuity and motor development are interconnected in preterm and VLBW populations. Benum et al.3 investigate visual acuity as a mediator between VLBW and fine and gross motor abilities, finding markedly different effects with visual acuity mediating up to 39% of fine motor skills but only 14% of gross motor skills. This difference likely reflects the greater dependence of fine motor skills on visual feedback, whereas gross motor skills rely more on proprioception and established movement patterns. The findings raise an important question: do these relationships reflect a causal pathway where visual acuity directly affects motor function, or shared aetiology, where common neurological damage affects both visual acuity and motor function? If causal, correcting visual acuity should significantly improve motor function. If reflecting shared aetiology, visual correction would help but cannot resolve motor problems since both are caused by underlying brain injury. Both explanations are likely at play here – some direct association between vision and motor control plus some independent effects of common brain injury. This dual mechanism may explain why visual correction improves but does not completely resolve motor problems. Understanding the link between visual acuity and motor outcomes is important given their long-term implications for other developmental outcomes and overall functioning, such as academic performance, participation, and quality of life. Comprehensive vision testing should be routine when evaluating VLBW children with motor problems, as treatable visual problems may be overlooked, particularly in young children where subjective refraction is more challenging. Correction of visual acuity problems through glasses, contact lenses, and other treatments could potentially improve motor outcomes in VLBW individuals. The substantial mediation effect (up to 39% for fine motor skills) reported by Benum et al.3 emphasizes that addressing visual acuity problems early is worthwhile. However, additional interventions remain necessary to optimize motor outcomes, given that VLBW is associated with delay and problems in several developmental domains. A multidisciplinary and multimodal approach for intervention and therapy will likely prove most effective. Realistic expectations are important as visual correction provides clear benefits, but cannot completely resolve motor problems. Poor vision can negatively affect motor learning through reduced visual feedback, difficulty with spatial awareness, and problems with hand–eye coordination. Early screening and regular follow-up assessments are important to ensure that timely interventions and support, including optimal visual correction, are provided to individuals with motor difficulties. Understanding the substantial role of visual acuity in motor outcomes enables more targeted and realistic approaches for intervention that acknowledge both the importance of visual correction and the need for comprehensive developmental support. Further research is needed to identify additional mechanisms linking VLBW and motor difficulties, enabling optimization of both short- and long-term outcomes for this vulnerable population. Open access publishing facilitated by Monash University, as part of the Wiley - Monash University agreement via the Council of Australian University Librarians. Not required.