Optic neuritis in Asian type opticospinal multiple sclerosis (OSMS-ON) in a non-Asian population: A functional-structural paradox

Background: Biomarkers have improved the classification of autoimmune inflammatory disorders, including optic neuritis (ON) as a frequent presentation of multiple sclerosis, neuromyelitis spectrum disorders, MOG antibody-related disease (MOGAD), and opticospinal multiple sclerosis (OSMS). The phenotype of OSMS in non-Asian populations is less well known. // Objective: We investigated the clinical features and prognosis of OSMS–ON in a Brazilian cohort. // Methods: This was a single-center cohort study of patients from Rio de Janeiro (Brazil) with OSMS. All individuals were MOG- and AQP4-seronegative, clinically diagnosed with ON, and had magnetic resonance imaging-confirmed transverse myelitis (TM). Subjects and healthy controls (HCs) were assessed for visual acuity (logMAR VA), automated perimetry mean deviation (MD), intraocular pressure, and spectral-domain optical coherence tomography (OCT), followed by automated retinal layer segmentation of the peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell and inner plexiform layer (mGCIPL). Receiver operator characteristic curves were plotted and the area under the curve (AUC) was calculated for group comparisons of retinal asymmetry of the pRNFL and mGCIPL. // Results: The 30 patients with OSMS were predominantly female and white. The mean age was 48 years (range 20–70 years). Unilateral ON was the index event in 83.3% of patients. Over the average 18-year follow-up period, there were 89 relapses of ON. In individuals with OSMS, the average VA was 0.07±0.14 in the right eye (RE) and 0.13±0.30 in the left eye (LE). The MD was −5.37±5.88 dB and −5.23±3.34 dB for the RE and LE, respectively. There was a significant cumulative loss of VA (p = 0.0003) and MD (p = 0.0001) with a higher number of recurrent episodes. Atrophy of the pRNFL thickness was significant in OSMS (RE, 78.62 ± 16.01 µm; LE, 79.86 ± 13.79 µm) relative to the HC group (RE, 98.87 ± 10.68 µm; LE, 97.87 ± 10.85 µm, p = 0.0001). Likewise, there was significant mGCIPL atrophy in patients with OSMS (RE, 74.96 ± 14.46 µm; LE, 73.88 ± 13.79 µm) relative to the HC group (RE, 90.50 ± 6.74 µm; LE, 90.41± 6.89 µm; p = 0.0001). Retinal asymmetry, inter-eye percentage, and absolute differences accurately separated patients with unilateral ON from HCs (AUC=0.89 and AUC=0.85, respectively). // Conclusion: A structural-functional paradox was found in OSMS with a high diagnostic value for a novel metric based on retinal asymmetry. The functional visual outcome are excellent despite significant structural damage to the inner retinal layers in patients with a high ON relapse rate and long-term bilateral sequential involvement

A 30 s test for quantitative assessment of a relative afferent pupillary defect (RAPD): the infrared pupillary asymmetry (IPA)

BACKGROUND: Detection of a relative afferent pupillary defect (RAPD) by the swinging-light test can be challenging in clinical practice (dark eyes, anisocoria, dark environment). We developed a new method of RAPD quantification based on the recording of the infrared pupillary asymmetry (IPA) with a standard optical coherence tomography (OCT) device. METHODS: The diagnostic value of the IPA for detection of the RAPD was determined by receiver-operating characteristic (ROC) curves and area under the curve (AUC). RESULTS: Twenty-nine subjects were included in this study (17 controls and 12 unilateral optic neuropathies). The IPA was significantly greater in unilateral optic neuropathies (0.39) compared to controls (0.18, p = 0.001). The diagnostic value was good with a ROC-AUC of 0.843. Importantly, the IPA correlated significantly with the inter-eye percentage difference of the macular ganglion cell-inner plexiform layer (mGCIPL) thickness (R = 0.53, p = 0.01). Assessment of the IPA took less than 30 s. CONCLUSION: The present data show that the IPA is a practical and rapid test that can be applied in a clinical setting. The IPA may be a valuable functional outcome measure for clinical trials, complementing structural retinal OCT data in a biological meaningful way. The IPA should be further investigated for suitability for optic neuritis treatment trials