Outer Retinal Dysfunction on Multifocal Electroretinography May Help Differentiating Multiple Sclerosis From...

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are inflammatory demyelinating diseases affecting the central nervous system.
• Retinal involvement, including optic nerve damage, is common in both MS and NMOSD, impacting visual function.
• Optical coherence tomography (OCT) and multifocal electroretinography (mf-ERG) are key tools for assessing retinal structure and function.

Purpose of the Study:

• To compare intermediate and outer retinal layer integrity in patients with MS and NMOSD.
• To investigate the utility of OCT and mf-ERG in differentiating retinal damage patterns between MS and NMOSD.
• To correlate retinal layer thickness with electrophysiological responses.

Main Methods:

• Cross-sectional study involving 30 MS patients, 30 NMOSD patients, and 29 healthy controls.
• Ophthalmic examinations included visual field testing, OCT for retinal layer thickness (mRNFL, GCL, IPL, etc.), and mf-ERG for P1 and N1 responses.
• Eyes were categorized into MS with/without optic neuritis (ON) and NMOSD with/without ON groups.

Main Results:

• Significant reductions in ganglion cell layer (GCL) and inner plexiform layer (IPL) thickness were observed in both MS and NMOSD groups compared to controls, with large effect sizes.
• Macular retinal nerve fiber layer (mRNFL) thickness was reduced in MS+ON, NMOSD+ON, and NMOSD-ON eyes, but not significantly in MS-ON eyes.
• mf-ERG showed shorter P1 and N1 peak times in MS patients, suggesting outer retinal dysfunction, but not in NMOSD patients. These functional changes correlated with retinal layer thinning.

Conclusions:

• mf-ERG results indicate outer retinal abnormalities in MS, which are not evident in NMOSD.
• OCT measurements revealed significant thinning of inner retinal layers (GCL, IPL) in both MS and NMOSD, regardless of ON history.
• The distinct mf-ERG findings suggest differing patterns of retinal damage between MS and NMOSD, aiding in understanding disease-specific pathophysiology.