OCT Pins Down MOGAD and MS Diagnosis in ON

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While optic neuritis (ON) can occur with both myelin oligodendro­cyte glycoprotein antibody–associat­ed disease (MOGAD) and multiple sclerosis (MS), treatment of the two demyelinating diseases differs. Now, researchers have found that OCT can be used to determine whether a patient has MOGAD-ON or MS-ON.¹

In the study, optic nerve edema was assessed with OCT-derived peripapil­lary retinal nerve fiber layer (pRNFL) thickness and shown to be more severe in eyes with MOGAD-ON than in eyes with MS-ON. Additionally, pRNFL thickening appears to be a sensitive bio­marker for confirming MOGAD-ON, the researchers said.

“We were not too surprised to find that the pRNFL during an acute optic neuritis attack was much thicker in MOGAD compared to MS overall, but the degree that OCT differentiated the two entities was quite striking,” said John J. Chen, MD, PhD, at the Mayo Clinic in Rochester, Minnesota.

Pathway to better outcomes. The findings can help guide acute treatment while the clinician awaits results of anti-body testing, Dr. Chen said. “MOG antibody test results typically return in one to two weeks, which may be outside the window of opportunity for early steroids to influence outcomes.” But based on this study, the presenta­tion of optic neuritis with significant pRNFL thickening would be suggestive of MOGAD, and such a patient should be treated with early steroids, he said. This is in contrast to MS-ON, for which steroid treatment has been found to speed up recovery but does not change the ultimate outcome,² Dr. Chen added.

“It is likely even more important to differentiate these entities when it comes to chronic treatment decisions,” he said. “For the most part, traditional MS medications are not effective for patients with MOGAD and vice versa. OCT may be able to help confirm cases of MOGAD in the setting of low MOG antibody titer, which has recently been shown to be a false positive in up to 50% of cases.”

In addition, it is important to have objective evidence of ON in clinical practice, Dr. Chen said, because patients often develop vague symptoms such as blurred vision and discomfort. “If a patient has these symptoms along with a significant increase in pRNFL thick­ness, we can be confident it is a true attack [of ON].” This is particularly the case with MOGAD, he said, “since every attack was associated with at least a 5 μm increase in pRNFL thickness.”

Study specifics. This retrospective multicenter case series included 64 MOGAD patients (96 eyes) and 50 MS patients (51 eyes) who underwent OCT within two weeks of onset of ON symptoms. None of the study eyes had experienced a previous ON attack. Of the MOGAD patients, 29 (45%) had bilateral simultaneous ON, compared with one (2%) of the MS patients.

The median pRNFL thickness was 164 μm in MOGAD-ON eyes and 103 μm in MS-ON eyes (p < 0.001). A cut­off value of 118 μm provided a sensi­tivity of 74% and specificity of 82% for the optic neuritis being from MOGAD. Among 31 MOGAD eyes and 48 MS eyes with baseline or comparator data, there was a median pRNFL thickening of 45 μm and 7.5 μm, respectively (p < 0.001).

What’s next? OCT-derived pRNFL thickening will be used in an upcoming clinical trial on MOGAD as one of the objective criteria to confirm an ON attack, Dr. Chen said.

—Patricia Weiser, PharmD

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1 Chen JJ et al. Mult Scler Relat Disord. 2022;58:103525.

2 Beck RW, Gal RL. Arch Ophthalmol. 2008;126(7):994-995.

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Relevant financial disclosures—Dr. Chen: None

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