Background: Previous work has demonstrated that higher levels of physical activity (PA) are associated with better retinal fiber integrity in children with multiple sclerosis (MS).

Objective: To determine whether high PA levels are associated with retinal fiber integrity through time in children with demyelinating disease.

Methods: Children with MS or monophasic acquired demyelinating syndromes (mono-ADS) were included. PA level was assessed by questionnaire, and a spectral-domain optical coherence tomography (OCT) scanner determined retinal nerve and ganglion cell inner plexiform fiber layer thickness (RNFL and GCIPL, respectively). Linear mixed models were used to analyze longitudinal associations.

Results: Children with MS (n = 28, 20F, mean age 14.6 (standard deviation (SD) ±2.4)) and mono-ADS (n = 24, 11F, mean age 9.5 (SD ±4.5)) took part. In children with MS, RNFL and GCIPL thickness was shown to decline by 1.0 mm (p < 0.05) over time. More active children with MS had thicker GCIPL through time compared to those who were inactive (2.5 mm, p < 0.01). Furthermore, taking part in any strenuous PA was associated with greater RNFL and GCIPL thickness (1.5-2.1 mm, p < 0.05). These differences were not found in children with mono-ADS.

Conclusions: Moderate to vigorous PA is associated with better retinal integrity over time in pediatric MS. Future interventions should evaluate whether changes to PA level coincide with changes to retinal integrity in children with MS.