Analysis of RNFL and GCL in patients with multiple sclerosis and fibromyalgia

Purpose: To evaluate the differences in RNFL and GCL between patients with relapsing–remitting multiple sclerosis (RR‐MS), fibromyalgia (FM) and healthy controls, as well as their correlation with disease time and severity. Methods: 94 eyes of RR‐MS patients, 55 eyes of FM patients and 90 eyes of healthy controls were evaluated using the Spectralis OCT Posterior Pole protocol (64‐cell array grid). The thicknesses of both layers were compared for each of the 64 cells between the three groups, the correlation of each layer with the time of the disease was studied, as well as with the EDSS in the case of RR‐MS and with the questionnaires FIQ and EQ‐5D in the case of FM. Results: We observed a significant thinning ( p < 0.05) of the GCL in both pathologies compared to healthy subjects, being the damage significantly greater in RR‐MS. Regarding the RNFL, a significant thinning was observed in the RR‐EM but not in the FM. On the other hand, GCL was correlated with the time of evolution in RR‐MS patients, but not in those with FM, and was significantly correlated with a greater impact of FM (FIQ and EQ‐5D), but not with the EDSS in the case of RR‐MS. In addition, it is in the GCL where a high concentration of cells (>50%) which a greater ability to discriminate between healthy and pathological subjects (AUC > 0.5) was found. Conclusions: The GCL damage in FM patients, similar to that in RR‐MS patients, suggests that there is an underlying neurodegenerative process in this pathology. In the absence of other biomarkers, OCT could be postulated as a potential biomarker in FM, since GCL shows significant thinning and correlates with the impact of this disease on quality of life.