IMG02
Longitudinal Stability of Inter-Eye Difference Thresholds By Optical Coherence Tomography in Multiple Sclerosis
Diagnostic criteria for multiple sclerosis (MS) do not include imaging of optic nerve lesions as a lesion site despite high prevalence of acute optic neuritis (ON). Previous studies have shown retinal nerve fiber layer (RNFL) and ganglion cell+ inner plexiform layer (GCIPL) thickness inter-eye differences (IEDs) are robust thresholds for identifying a history of optic neuritis (ON) in people with multiple sclerosis (PwMS).
Objectives: This study investigates the utility of these measures as longitudinal biomarkers for inter-eye stability.
Methods: This is a prospective, single-site cohort study of PwMS (with and without ON) and healthy controls. Optical coherence tomography (OCT) was obtained during study visits at two time points with Spectralis (Heidelberg Engineering, Heidelberg, Germany) or Cirrus OCT (Carl Zeiss Meditec, Dublin, CA). PwMS with acute ON at time of OCT were excluded. Paired t-tests were used to compare IEDs for the whole cohort and within disease groups.
Results:
A total of 73 participants were included (9 healthy controls and 64 PwMS). Average age of those with MS was 42.0±11.7 and 44/64 (70.0%) had a relapsing-remitting subtype. 25/64 (39.1%) patients had a history of acute unilateral ON, and 7/64 (10.9%) had a recurrent episode of ON. Median follow up time was 3 months (IQR: 0 – 10 months). IEDs were stable between first and last visits for the whole cohort (p=0.821), and within groups for GCIPL (healthy controls (p=0.217), PwMS with (p=0.217) and without ON (p= 0.164). They were also stable on RNFL: control (p=0.173), PwMS without ON (p = 0.685), PwMS with ON (p = 0.211)
Conclusions:
This study demonstrates the stability of inter-eye differences in a longitudinal OCT cohort of MS patients. In those without a history of episodes of acute optic neuritis at the time of scanning, inter-eye differences also remain stable over time. These results provide further evidence that inter-eye differences in OCT-measured retinal thicknesses may serve as a marker for optic nerve lesions to add to the diagnostic criteria for MS.