A study using noninvasive optical coherence tomography (OCT) detected axonal damage in the optic nerve in patients with fibromyalgia (n = 116) as compared with controls (n = 144), suggesting that neurodegeneration contributes to the pathology of the disease, Thinning of the retinal nerve fibre layer did not correlate with disease duration or severity, but was more pronounced in the subgroup of patients with 'biologic' fibromyalgia according to the Giesecke classification scheme.