RNFL thickness in MS-associated acute optic neuritis using SD-OCT: critical interpretation and limitations

Area of Science:

• Ophthalmology
• Neurology
• Medical Imaging

Background:

• Axonal loss is a critical prognostic indicator in multiple sclerosis (MS).
• Retinal nerve fibre layer thickness (RNFLT) is a key measure for monitoring MS progression.
• Spectral-domain optical coherence tomography (SD-OCT) is an advanced imaging technique.

Purpose of the Study:

• To investigate if high-resolution SD-OCT measurements of RNFLT differ between optic nerve injury from acute optic neuritis (ON) and subclinical axonal damage in MS patients.
• To assess the capability of SD-OCT in detecting unregistered axonal damage in MS.

Main Methods:

• High-resolution SD-OCT measurements of RNFLT were performed in 25 MS patients and 25 healthy controls during the acute phase of ON and 3 months later.
• RNFLT was measured in peripapillary sectors (PPs).
• A measurement model comparing MS patients to their fellow eye and age/sex-matched controls was utilized.

Main Results:

• Conventional OCT analysis identified swelling but missed some RNFLT decreases.
• RNFLT symmetry comparison revealed previously unregistered axonal damage.
• A segmental RNFL loss was detected in 72% of first-episode ON eyes at baseline, increasing over time.
• A global RNFL loss was registered in 36.4% of eyes.

Conclusions:

• SD-OCT imaging with optimized scan centring can detect subtle, unregistered optic nerve injury in MS.
• Comparing OCT metrics with the fellow eye and controls is crucial for identifying RNFLT discrepancies and prior ON.
• This technology holds potential for improved diagnosis and monitoring of MS.