Abstract
Purpose :
Correctly identifying prior optic neuritis is critically important because the presence or absence of optic neuritis may confirm or refute a diagnosis of neurologic conditions, such as multiple sclerosis and neuromyelitis optica. Prior studies have suggested that optical coherence tomography (OCT) has a sensitivity of 68% for detecting prior optic neuritis. However, they used two standard deviations below age matched controls as “abnormal”. This can be an insensitive measure because patients have different baseline thicknesses. We believe that looking at inter-eye differences in cases of unilateral optic neuritis would be more sensitive in detecting prior optic neuritis. Thus, we evaluated the sensitivity of Cirrus OCT in detecting prior unilateral optic neuritis.
Methods :
We performed a retrospective, observational clinical study of all patients with unilateral optic neuritis who presented between 2014 and 2016. Patients were included if they had unilateral optic neuritis and had OCT done at least 3 months after the optic neuritis (range of 3-44 months). Optic neuritis was confirmed radiographically in 70.5% of patients and the remainder were diagnosed clinically. We compared OCT retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thicknesses between the affected and unaffected, contralateral eyes. We excluded patients with concomitant glaucoma or other optic neuropathies. Paired T-test was used to compare RNFL and GCL thicknesses between eyes. In calculating sensitivity, thinning was considered significant if the RNFL or GCL was at least 6µm less in the affected eye compared to the unaffected.
Results :
A total of forty-four patients (15 male and 29 female) were included in the study. RNFL and GCL thicknesses were significantly lower in eyes with optic neuritis compared to unaffected eyes (p≤0.002). RNFL was thinner by ≥6µm in 84.1% of optic neuritis eyes compared to the unaffected eye. GCL was thinner by ≥6µm in 95.2% optic neuritis eyes. The sensitivity of OCT in detecting prior optic neuritis was 97.7% when using both average RNFL and GCL thicknesses. When using a cutoff of ≥2 standard deviations below age-matched controls, sensitivities were 59.1% for RNFL, 81.0% for GCL, and 81.8% for either GCL or RNFL thicknesses.
Conclusions :
OCT is a highly sensitive modality in detecting prior optic neuritis, which is made more robust by using inter-eye differences to approximate change and combining GCL and RNFL data.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.