Editor Response: Asymptomatic Optic Nerve Lesions: An Underestimated Cause of Silent Retinal Atrophy in MS.

Abstract

Davion et al.1 examined the frequency of asymptomatic optic nerve MRI signal in patients with multiple sclerosis (MS) on natalizumab. All patients were seronegative or had low antibody titers for JC virus (<1.50). The authors found that 60 or 73 (82.2%) eyes with a history of symptomatic optic neuritis (ON) had high signal on MRI of the orbits using 3D double inversion recovery (DIR). There were 123 asymptomatic eyes with no history of ON; nearly 50% of these eyes also showed high signal using DIR MRI. The DIR MRI findings were examined in the context of optical coherence tomography (OCT) findings and low-contrast letter acuity (LCLA) performance. This publication is of significance for several reasons. First, it shows the rate of high signal abnormality in a chronic cohort of symptomatic optic neuritis eyes. The case series also demonstrates a high rate of DIR-identified high signal change in asymptomatic eyes; the association of this finding with reduced OCT-measured retinal thickness values and impaired monocular LCLA scores is also highlighted. Results from DIR imaging of the asymptomatic eyes are notable since the most recent 2017 McDonald Criteria for MS diagnosis do not include optic nerve lesions as part of the criteria for dissemination in space by MRI.2 Thus, OCT imaging and DIR MRI may be valuable to detect subtle symptomatic or asymptomatic optic nerve abnormalities.1,3 Ongoing investigations will need to confirm the value of DIR imaging to define potential false-positive rates for identifying optic nerve disease vs changes in imaging without functional impairment. This study and others that document OCT-measured intereye differences should lead to further investigation into the role of the optic nerve as a lesion site for MS diagnosis.