Homonymous hemimacular thinning of the retinal ganglion cell-inner plexiform layer (GCIPL) on optical coherence tomography (OCT) in the absence of significant visual field defects may be identified in the workup of patients with visual complaints, but the causes of this finding remain unknown. We retrospectively reviewed 1425 consecutive patients referred for neuro-ophthalmic assessment who had high quality OCT scans and reliable Humphrey 24-2 SITA-Fast testing. A total of 7 patients, 3 females and 4 males, with a mean age of 39.4 ± 10.5 years that had homonymous thinning of the OCT macular-GCIPL without significant visual field defects were included in the study. Four patients had demyelinating disease and 3 patients had traumatic brain injury. Three patients with demyelinating disease had a documented prior homonymous visual field defect that resolved. The differential diagnosis of homonymous hemimacular thinning of the GCIPL without obvious visual field defects includes previous retrochiasmal demyelination and traumatic brain injury. OCT GCIPL provides a permanent objective way of documenting previous retrochiasmal disease including demyelination and may be helpful in establishing dissemination in time and space in patients being evaluated for multiple sclerosis.