Border tissue morphology is associated with macular ganglion cell thickness in open-angle glaucoma

Externally oblique border tissue (EOBT) configuration is topographically associated with glaucomatous damage in the optic nerve head. We investigated the relationship between the EOBT characteristics and macular retinal ganglion cell (RGC) thickness in patients with open-angle glaucoma (OAG). A total of 149 eyes with OAG that had an EOBT observed on optical coherence tomography exams were included. After determining the maximum EOBT length and angular location of the maximal EOBT length, we analyzed their correlation with macular ganglion cell inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thickness. The macular GCIPL and pRNFL thickness were compared based on the angular location of the longest EOBT, and their association was assessed using multivariable regression analysis. Maximum EOBT length was significantly correlated with macular GCIPL thickness, but not with pRNFL thickness. Macular GCIPL was thinnest in eyes with EOBT located in a temporal direction to the optic disc. Longer maximum EOBT and temporally elongated EOBT were independently associated with a thinner macular GCIPL in the multivariable regression analysis. These suggest that temporal elongation of the EOBT may increase the stress and strain on the RGCs derived from the macula and make RGCs more susceptible to glaucoma-inducing damage.