We conducted a feasibility study to evaluate the feasibility of recruiting patients to examine the effect of near vision glasses in young infants at risk of cerebral visual impairment.

A three-arm, parallel-group, open-label randomised feasibility trial.

Tertiary neonatal intensive care in London, UK.

We included babies born before 29 weeks of gestation or at full term with hypoxic ischaemic encephalopathy. Babies who needed ongoing inpatient care, with established eye anomalies or with very high refractive errors at baseline (±8.00D) were not included. Infants with retinopathy of prematurity were not excluded.

At 8 weeks corrected age, we allocated 18 infants to wear glasses (+3.00D over full cycloplegic refraction) immediately (intervention 1), 18 to wear the same glasses at 16 weeks (intervention 2) and 19 infants were allocated to standard treatment (no glasses).

Recruitment and retention of study participants (primary), compliance wearing glasses, preferential-looking visual acuity (with glasses) and visual function as determined using A Test Battery of Child Development for Examining Functional Vision at 3-month and 6-month age post-term.

Of 70 eligible families, 55 consented and 34 attended baseline assessments, and 28 completed the study. Non-attendance was due mainly to prolonged inpatient stay, infant health and scheduling conflicts. Glasses were worn for similar periods in each group (Intervention 1: median 2 hours/day (95% CI 1 hour to 4 hours); Intervention 2: median 2 hours/day (95% CI 1.5 hours to 3 hours)). Visual acuity improved from baseline to 6 months. Mean (SE) LogMAR (Minimum Angle of Resolution) improvements were standard care: 0.47 (0.45); intervention 1: 0.66 (0.44); intervention 2: 0.37 (0.36). Among the 29 very preterm infants, there were similar findings: standard care: 0.35 (0.35); Intervention 1: 0.67 (0.47); Intervention 2: 0.34 (0.40). As a functional measure, object permanence was present at the following rates by randomised arm: standard care: 29%; whereas intervention 1: 56%; and intervention 2: 44% (OR intervention 1 vs standard care: 3.13 (95% CI 0.38 to 25.57), ie, not statistically significant).

We demonstrate feasibility for a definitive RCT (randomized controlled trial) with good recruitment and retention and observed potential benefits for vision and development following the dispensing of glasses at 8 weeks post-term age compared with untreated controls. We identified methodological modifications to further improve recruitment processes for a future larger study.

ISRCTN14646770; NCT05048550.

Despite an increasing use of screens among preschool children and evidence suggesting potential adverse effects, there is a paucity of longitudinal research that aims to disentangle the multifaceted components of screen use and their unique associations with development. We present a protocol for a large-scale national longitudinal study with repeated measurements in Danish preschool children, with the aim of investigating the cross-sectional and cross-lagged longitudinal associations between screen use and psychological outcomes.

The Digital Child Study is a national prospective observational cohort of Danish preschool children. Baseline parent-report data collection commenced in 2024 via online questionnaires, and in total will include three time points over 1 year: baseline (age 4 years), and follow-ups at 6 and 12 months (ages 4.5 and 5 years). Participants were divided into two waves based on birth dates, starting in March and September 2024. Recruitment targeted parents and primary caregivers of all Danish children born between specific dates in 2020. Of 30 235 children whose parents were sent invitations, baseline questionnaire data were available for 11 690 (39%).

Children’s screen use was measured by detailed information of amount, content and timing of children’s screen use, and the broader context, incorporating parental mediation strategies, attitudes, motivations and practices. Cognitive and socioemotional developmental outcomes were measured using validated tools such as the Strengths and Difficulties Questionnaire, the Nordic Five-to-Fifteen parent questionnaire and the Behaviour Rating Inventory of Executive Function—Preschool Version. Questionnaire data will be linked to national social and health registries to enable long-term follow-up. Statistical analyses will include longitudinal modelling to explore associations between screen use and developmental outcomes, with sensitivity analyses for robustness. The study’s large sample size provides high statistical power to detect meaningful effects.

The study adheres to ethical research guidelines, ensuring voluntary participation, confidentiality and compliance with data protection laws, with approvals from relevant authorities. Findings will be disseminated through peer-reviewed publications, conferences and plain-language summaries to engage stakeholders and the broader community.