NeuroVoices: Rachel Kenney, PhD, on Integrating OCT Into the 2024 McDonald Criteria for Multiple Sclerosis

Optical coherence tomography (OCT) has emerged as a valuable, noninvasive modality for assessing neuroaxonal damage in multiple sclerosis (MS), particularly through evaluation of retinal structures associated with optic nerve injury.¹ As MS diagnostic frameworks evolve, clinicians are increasingly considering how OCT-derived metrics may complement established tools such as MRI, visual evoked potentials, and clinical examination. The incorporation of the optic nerve as a formal lesion site in updated diagnostic criteria highlights the growing recognition of optic neuritis and visual pathway damage as central components of MS pathology.

At the recently concluded 2026 Consortium of Multiple Sclerosis Centers (CMSC) Annual Meeting, held May 27-29, Charlotte, North Carolina, Rachel Kenney, PhD, assistant professor of neurology and population health at NYU Grossman School of Medicine, presented on the role of OCT in the 2024 McDonald Criteria for MS.¹ Her discussion focused on how specific OCT measures, such as intereye asymmetry in the peripapillary retinal nerve fiber layer and ganglion cell layer, can serve as objective evidence of optic nerve injury. She also addressed the advantages of OCT over conventional MRI for detecting subtle structural damage, as well as the need for standardization and rigorous quality control in routine practice.

In a new iteration of NeuroVoices, Kenney further explored the practical integration of OCT into MS diagnostic workflows under the updated criteria. She outlined where OCT adds the most value compared with traditional imaging, highlighted key implementation challenges related to image acquisition and interpretation, and emphasized the importance of ruling out alternative retinal or optic nerve pathologies. Kenney also provided her perspective on how improved training, protocol harmonization, and comprehensive patient evaluation can help ensure that OCT is used appropriately as a diagnostic adjunct in MS.

NeurologyLive: How do you see OCT being integrated into clinical practice based on the new criteria for MS?

Rachel Kenney, PhD: I'm very excited that the optic nerve is now a fifth lesion site in the diagnostic criteria for MS. As many clinicians know, optic neuritis is highly prevalent in MS, but it hadn't quite made it into the diagnostic criteria yet—so now it has.

OCT is a great tool that can be used to look for neuroaxonal injury in the visual pathway. In conjunction with VEP, MRI, and clinical examination, OCT can now be used as evidence of optic nerve injury to count toward the MS diagnostic criteria. As optic neuritis is often unilateral in MS, there can be a resultant asymmetry between the 2 eyes. When we're measuring specific areas in the retina, one area is directly surrounding the optic nerve; it's called the peripapillary retinal nerve fiber layer.

There can be an asymmetry, or intereye difference, when you compare the 2 eyes, and those thresholds, which are about 5 to 6 microns for the retinal nerve fiber layer, can now be used as evidence of optic nerve injury. Similarly, in the macular region, there's an area called the ganglion cell layer, where if you look for an intereye asymmetry of 4 microns, that can now be used also as evidence of optic nerve injury to help aid in the diagnosis of MS.

Where does OCT add the most value compared with traditional MRI and clinical examination when evaluating patients for suspected MS?

The great thing about OCT is it's relatively easy on the patient. They put their head on a chin rest, and the machine takes an image of the back of their eye. It's not invasive, and it's fairly cost-effective. It's actually much higher resolution than an MRI; we're talking on a scale of microns, as opposed to millimeters. So, it can detect structural injury in the neuroaxonal layers of the retina that may not be detectable by other metrics.

Optic nerve imaging to date on MRI hasn't been that common. It's a very small structure; it's not routinely done as part of MS evaluations. Maybe it will be now, since it's part of the criteria, but it hasn't been routinely done in the past. Whereas OCT has been well validated; it's been used now for over 15 years and is used regularly in ophthalmology practices. It has great standardization, and it can detect very subtle changes.

For example, a patient could be having an acute optic neuritis, and an OCT could pick up a very subtle swelling, or in the chronic phase, it can even pick up subclinical degeneration. Even in the event where a patient hasn't had any kind of clinical symptom—hasn't had anything to indicate that they've had an acute optic neuritis—you can still measure that there has been some degeneration.

What practical challenges still need to be addressed before OCT can be fully adopted in routine practice as a reliable diagnostic adjunct in MS workups?

I think that's a really, really important question. Standardization and interpretation are the 2 big points. With standardization, there need to be consistent protocols. There needs to be proper training for the technicians. The clinicians need to understand when an image looks good, what the criteria are for proper quality control. For interpretation, clinicians need to understand how to read the images; they need to understand what they're looking for.

Most importantly, they need to make sure that they are not considering something that's not MS as MS. There are other things like glaucoma, macular pathologies, high myopia—there are other things that could potentially cause asymmetry in the retina that need to be ruled out first before using OCT as a way to say, “This is MS-related.”

Is there anything else you would like to add about OCT’s role in the updated diagnostic criteria for MS?

Despite the challenges—with proper training, with proper understanding of quality control, with proper evaluation, making sure the whole retina is evaluated and the whole person is considered—OCT is an excellent tool. It's highly sensitive, it's easy on the patient, it's cost-effective, and we know that patients with MS are highly affected by visual dysfunction. This is going to be an excellent addition to the diagnostic criteria.

Transcript edited for clarity. Click here for more coverage of CMSC 2026.

REFERENCES
1. B Saidha S, Green AJ, Leocani L, et al. The use of optical coherence tomography and visual evoked potentials in the 2024 McDonald diagnostic criteria for multiple sclerosis. Lancet Neurol. 2025;24(10):880-892. doi:10.1016/S1474-4422(25)00275-32.
2. Kenney R. OCT in the 2024 McDonald Criteria. Presented at: 2026 CMSC Annual Meeting; May 27-29; Charlotte, North Carolina. OCT Across the Spectrum of Demyelinating Disease.