The aim of this study was to evaluate the relationship between retinal layer thickness, cortical lesions (CLs) and disability at the onset of the first demyelinating event (a clinically isolated syndrome (CIS), suggestive of multiple sclerosis (MS).

Neuroaxonal degeneration is considered the primary cause of permanent disability in patients with MS, thus new biomarkers to quantify neurodegeneration are needed. Reduced retinal layer thickness in MS exists irrespective of optic neuritis (ON) and has been correlated with disability and brain atrophy. In CLs, neuroaxonal degeneration is also present.The relationship between retinal atrophy, CLs and disability in CIS is not well established. 

We performed a cross-sectional evaluation of thirty-nine patients with CIS known to have CLs as identified on 3T brain MRI, who also underwent Optical Coherence Tomography to quantify retinal layer thickness. We excluded affected eyes in ON patients and used the average values of both eyes in patients without ON. We performed linear regression analyses to evaluate the relationships between the retina measures and CLs characteristics as well as clinical outcomes. Significant results with p<0.05 are reported.

We found that a thinner combined ganglion cell-inner plexiform layer (GCIPL) was associated with higher juxtacortical lesion numbers and volumes. A thinner peripapillary retinal nerve fiber was associated with higher leukocortical, juxtacortical and total cortical lesion volumes. A thinner GCIPL was correlated with greater disability as measured by the expanded disability status scale. A reduced thickness of GCIPL and inner nuclear layer were associated with MS diagnosis at presentation. 

This study provides support for a relationship between increased cortical damage and retinal layers thinning in CIS suggesting a common pathological process behind these alterations. The association between greater retinal damage and disability confirms the role of GCIPL as a possible biomarker of neurodegeneration even at this early stage of the disease.