• Neuro-Ophthalmology/Orbit

    The optic nerve is a frequent site for involvement in multiple sclerosis (MS). Using OCT, the authors sought to determine optimal thresholds for intereye difference in peripapillary retinal nerve fiber layer (RNFL) thickness that are most predictive of a unilateral optic nerve lesion.

    Study design

    The study included 31 healthy volunteer participants and 124 patients with MS. Each underwent OCT imaging to assess intereye differences in peripapillary (360°) RNFL thickness.

    Outcomes

    Among the healthy participants, the 95th percentile value for RNFL intereye differences (upper boundary of expected for normal controls) was 6.0 μm. The 6-μm threshold was predictive of worse binocular low-contrast acuity scores at 2.5% (P=0.03) and 1.25% (P=0.002).

    A receiver operating characteristic curve analysis demonstrated that the optimal intereye RNFL difference threshold for identifying unilateral ON within the MS cohort was 5 μm.

    Limitations

    There were some limitations to the study, including the small sample size and its single-center design.

    Clinical significance

    Current international diagnostic criteria for MS do not include optic nerve lesion imaging despite the high prevalence of acute optic neuritis or occult optic neuropathy among most MS patients over the course of the disease. This study shows that an intereye difference of 5 to 6 μm in RNFL thickness is a robust structural threshold for identifying the presence of a unilateral optic nerve lesion in MS.