Variations of retinal nerve fiber layer thickness and ganglion cell-inner plexiform layer thickness according to the torsion direction of optic disc

Purpose. To examine the relationship between the optic disc torsion and peripapillary retinal nerve fiber layer (RNFL) thickness through a comparison with the macular ganglion cell inner plexiform layer complex (GCIPL) thickness measured by Cirrus optical coherence tomography (OCT). Methods. Ninety-four eyes of 94 subjects with optic disc torsion and 114 eyes of 114 subjects without optic disc torsion were enrolled prospectively. The participants underwent fundus photography and OCT imaging in peripapillary RNFLmode and macular GCIPL mode. The participants were divided into groups according to the presence or absence of optic disc torsion. The eyes with optic disc torsion were further divided into supranasal torsion and inferotemporal torsion groups according to the direction of optic disc torsion. The mean RNFLand GCIPL thicknesses for the quadrants and subsectors were compared. The superior and inferior peak locations of the RNFLwere also measured according to the torsion direction. Results. The temporal RNFLthickness was significantly thicker in inferotemporal torsion, whereas the GCIPL thickness at all segments was unaffected. The inferotemporal optic torsion had more temporally positioned superior peak locations of the RNFLthan the nontorsion and supranasal-torted optic disc. Conclusions. Thickening of the temporal RNFLwith a temporal shift in the superior peak within the eyes with inferotemporal optic disc torsion can lead to interpretation errors. The ganglion cell analysis algorithm can assist in differentiating eyes with optic disc torsion.