Do eyes with and without optic neuritis in multiple sclerosis age equally?

Area of Science:

• Ophthalmology
• Neuroscience
• Multiple Sclerosis Research

Background:

• The anterior visual pathway in multiple sclerosis (MS) is affected by both optic neuritis (ON) and neurodegeneration.
• Axonal injury from ON is typically considered complete by 6 months post-onset.
• Current optical coherence tomography (OCT) studies often exclude or separately analyze eyes with a history of ON when assessing neurodegeneration in MS.

Purpose of the Study:

• To determine if eyes with a history of ON (>6 months post-onset) exhibit different chronic retinal changes over time compared to fellow eyes without ON in patients with MS.
• To evaluate the long-term comparability of retinal nerve fiber layer (RNFL) thickness between ON-affected and unaffected eyes in MS patients.

Main Methods:

• A cohort of 56 MS patients with unilateral ON history was selected.
• Paired eye analysis was conducted using optical coherence tomography (OCT) over a follow-up period exceeding 2 years.
• Retinal nerve fiber layer (RNFL) thickness in the peripapillary area was measured and compared between ON-affected and fellow eyes.

Main Results:

• The mean interval post-ON at baseline was 5.65 years, with a mean OCT follow-up of 4.57 years.
• No statistically significant difference was found in the absolute or relative thinning of the peripapillary retinal nerve fiber layer between eyes with a history of ON and their unaffected fellow eyes.
• These results indicate equal long-term RNFL changes in both groups.

Conclusions:

• Eyes with a history of ON do not need to be excluded from longitudinal studies of neurodegeneration in MS, especially when focusing on chronic changes beyond the acute phase post-ON.
• Long-term peripapillary RNFL changes are comparable between ON-affected and unaffected eyes in MS patients.
• OCT data from eyes with prior ON can be reliably integrated into MS neurodegeneration research, enhancing study inclusivity and data richness.