Loss to follow-up and increase in cup-to-disc ratio among glaucoma patients in the IRIS Registry.

Infancy is a crucial time for rapid brain growth and development. Early experiences, such as interactions with caregivers, exposure to language, and exploring the world, are key in shaping development. Neuroplasticity is maximal during these early years (; ), and this phase is vital for building the foundation of cognitive, emotional, and social skills, laying the groundwork for future learning and overall well-being. This period in life is also marked by rapid changes in motor skills, starting with basic reflexive movements and progressing to more complex actions that require greater coordination, control, and precision (; ). Of import, there is increased pressure on clinicians and researchers to obtain both quick and accurate assessments of infants whose development status must be assessed. Tools to track rapid developmental changes in early life are crucial for identifying milestones, addressing delays, and supporting optimal growth during this critical period (; ). The NIH Baby Toolbox (Baby Toolbox) is a promising new tool for assessing early childhood development and changes within the domains of Cognition, Motor, and Social-Emotional Functioning (). It was designed to provide a set of easy-to-administer, highly accessible computerized assessments for use in early childhood. Within each domain, several abilities or sub-domains are assessed. The Cognition domain assesses receptive language, expressive language, math, executive function, attention, learning, and memory across 14 individual measures. The Motor domain is comprised of two core measures and one supplemental measure, spanning gross and fine motor subdomains. Finally, the Social-Emotional Functioning domain has 13 core measures, spanning temperament, negative affect, psychological well-being, self-regulation, social relationships, and social communication subdomains. See (), this issue, for a full list of the Baby Toolbox measures. Though researchers and clinicians may consider measures of these more discrete skills separately, some may be interested in a smaller set of composite scores summarizing subdomain scores. Combining multiple measures into a single composite score potentially reduces the influence of measurement error and scaling issues across measures (; ; ) and provides a holistic view of the underlying construct, potentially improving the validity and precision of interpretation. Moreover, a composite score can help with aiding assessment of the construct over time, particularly if certain measures are age-banded, and the age-appropriateness of measures comprising the composite changes across the early lifespan. Composite scores have also been increasingly used in other developmental batteries, such as the Bayley Scales of Infant and Toddler Development () and Battelle Developmental Inventory ().