Purpose To evaluate the thickness of the inner retinal layers in the macula using frequency domain-optical coherence tomography (fd-OCT) in patients with demyelinating diseases. Design Cross sectional study Participants 301 eyes of 176 subjects were evaluated. Subjects were divided in 5 different groups: controls, neuromyelitis optica (NMO), longitudinally extensive transverse myelitis (LETM), multiple sclerosis with (MS-ON) and without (MS non-ON) history of optic neuritis, respectively. Methods The individual layers from macular fd-OCT cube scans were segmented with an automated algorithm, and then manually hand-corrected. For each scan, we determined the thickness of the retinal nerve fiber layer (RNFL), the combined retinal ganglion cell and inner plexiform layers (RGCL+), and the inner nuclear layer (INL). Main outcome measures Macular RNFL, RGCL+ and INL thickness Results The RNFL was significantly thinner than controls for all patient groups (p≤0.01). Macular RGCL+ thickness was significantly thinner than controls for the NMO, MS-ON and MS non-ON (p<0.001 for the 3 groups). The INL thickness was significantly thicker than controls for the NMO (p=0.003) and LETM (p=0.006) patients but not for MS-ON or MS non-ON. While the RNFL and RGCL+ were not significantly different between the NMO and MS-ON groups, the NMO patients had a significantly thicker INL than the MS-ON (p=0.02) patients. Conclusion Macular RNFL and RGCL+ demonstrate axonal and neural loss in MS, either with or without ON, and in NMO patients. In addition, the INL thickening occurs in NMO and LETM patients and study of this layer may hold promise for differentiating between NMO and MS.