Fig. 2: Representative CCM images in each group.

CCM images in healthy controls (a, d, g), PD (b, e, h) and SP (c, f, i). The corneal nerve plexus is beaded, linear homogeneous and highly reflective (a-c). Nerve fiber trunks are highlighted in red; branch origins are represented by the green dots (d-f) and corneal nerve fiber length is shown in green line (g–i). Images (d–f) were analyzed with the manual software (CCMetrics) and images g-i were marked with the automated version (ACCMetrics). Scale bar=100 µm. CCM corneal confocal microscopy, PD Parkinson’s disease, SP secondary parkinsonism.