Interactions of optic radiation lesions with retinal and brain atrophy in early multiple sclerosis

Objective Retrograde trans‐synaptic neuroaxonal degeneration is considered a key pathological factor of subclinical retinal neuroaxonal damage in multiple sclerosis (MS). We aim to evaluate the longitudinal association of optic radiation (OR) lesion activity with retinal neuroaxonal damage and its role in correlations between retinal and brain atrophy in people with clinically isolated syndrome and early MS (pweMS). Methods Eighty‐five pweMS were retrospectively screened from a prospective cohort (Berlin CIS cohort). Participants underwent 3T magnetic resonance imaging (MRI) for OR lesion volume and brain atrophy measurements and optical coherence tomography (OCT) for retinal layer thickness measurements. All pweMS were followed with serial OCT and MRI over a median follow‐up of 2.9 (interquartile range: 2.6–3.4) years. Eyes with a history of optic neuritis prior to study enrollment were excluded. Linear mixed models were used to analyze the association of retinal layer thinning with changes in OR lesion volume and brain atrophy. Results Macular ganglion cell‐inner plexiform layer (GCIPL) thinning was more pronounced in pweMS with OR lesion volume increase during follow‐up compared to those without (Difference: −0.82 μm [95% CI:‐1.49 to −0.15], p = 0.018). Furthermore, GCIPL thinning correlated with both OR lesion volume increase (β [95% CI] = −0.27 [−0.50 to −0.03], p = 0.028) and brain atrophy (β [95% CI] = 0.47 [0.25 to 0.70], p