Sex differences and subclinical retinal injury in pediatric-onset MS.

Objective: To assess retinal ganglion cell (RGC) injury and sex differences in axon loss in pediatric multiple sclerosis (MS).
Methods: This is a cross-sectional evaluation of consecutive pediatric MS subjects and controls. Eyes with acute optic neuritis (ON) within 6 months of visit were excluded. Spectral domain optical coherence tomography (OCT) included peripapillary ring and macular scans with post-acquisition segmentation of retinal layers using automated software (Heidelberg v1.8.6.0). Generalized estimating equations (GEEs) measured associations of sex, history of ON, disease duration, and age with OCT outcomes.
Results: In all, 53 MS subjects (100 eyes, median disease duration = 1.0 years, interquartile range (IQR) = 0.3, 2.5) were compared to 19 control subjects (38 eyes). Eyes with history of ON showed reduced retinal nerve fiber layer (RNFL: -26.8 µm, 95% confidence interval (CI) = -38.9, -14.8, p < 0.001) and 26% lower ganglion cell layer (GCL) volumes (-0.12 mm ³ , 95% CI = -0.16, -0.072, p < 0.001) compared to control eyes. Non-ON MS eyes had lower temporal RNFL (-11.9 µm, 95% CI = -18.6, -5.3, p < 0.001) and GCL volumes (-0.036 mm ³ , 95% CI = -0.06, -0.011, p = 0.004) than control eyes. In MS eyes, males versus females had lower global RNFL (-9.4 µm, 95% CI = -17.4, -1.33, p = 0.022) and in ON eyes had lower temporal quadrant RNFL (-9.6 µm, 95% CI = -15.1, -4.15, p = 0.001).
Conclusion: Subclinical retinal injury occurs in pediatric-onset MS patients without a history of ON. As in adult-onset MS, substantial GCL thinning is present in eyes with prior ON. Finally, greater retinal axonal injury occurs in boys compared to girls.