To investigate circumpapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thicknesses as measured by optical coherence tomography in eyes with situs inversus of optic discs.

RNFL and macular GCIPL thicknesses were measured in eyes with situs inversus of optic discs without other ocular abnormalities (situs inversus group) and in age- and refractive error-matched healthy eyes (control group). RNFL thickness (global area, superior, nasal, inferior, and temporal quadrants) and GCIPL thickness (global area, superior-temporal, superior, superior-nasal, inferior-nasal, inferior, and inferior-temporal sectors and minimum) were compared between the groups.

Nine eyes of 5 subjects with situs inversus of optic discs and 20 healthy eyes of 20 subjects (10 eyes for control groups A and B, respectively) were enrolled. No significant difference was found in superior or inferior quadrant RNFL thickness ( p > 0.05); however, the situs inversus group showed a thicker RNFL in the nasal quadrant and a thinner RNFL in the temporal quadrant ( p < 0.01). In macular GCIPL thickness, no significant difference was found in the superotemporal or inferiotemporal sector or for minimum thickness ( p < 0.05); however, the situs inversus group showed thicker GCIPL in the global area, superior, superonasal, inferonasal, and inferior sectors than the control groups ( p < 0.01).

In eyes with situs inversus of optic discs, distribution of circumpapillary RNFL and macular GCIPL thickness were different from eyes without this condition. When assessing RNFL and macular GCIPL thicknesses in eyes with situs inversus of optic discs, caution is needed.