Transverse Separation of the Outer Retinal Layer at the Peripapillary in Glaucomatous Myopes

Glaucoma specialists often overlook the outer retinal changes because the glaucomatous optic neuropathy typically involves retinal nerve fiber layer (RNFL). By detailed inspection of the outer retina in myopic eyes, we observed a separation of the inner nuclear layer (INL) from the outer nuclear layer (ONL) at the peripapillary sclera (pp-sclera). Therefore, we conducted a retrospective observation of 108 eyes of 108 Korean subjects with myopia assessed by swept-source optical coherence tomography (SSOCT) and divided into normal and glaucomatous eyes. Mean subject age, refractive error and axial length difference between 2 groups were insignificant, respectively. To quantify the ONL-INL separation, straight-line distance from ONL endpoint to INL endpoint was measured at the center of the optic disc by SSOCT horizontal scan. The glaucomatous group had significantly large ONL-INL separation than the non-glaucomatous group (p = 0.027) but had no significant difference in INL - Anterior scleral canal opening (ASCO) separation. The width of ONL-INL separation were associated with β-peripapillary atrophy (β-PPA), degree of horizontal tilt of the optic disc and worse glaucomatous RNFL defect by Pearson's correlation analysis (all p < 0.001, respectively). In conclusion, we demonstrate transverse separation of INL from ONL at the peripapillary region, which was significantly associated with glaucomatous optic nerve damage. These observations may be of interest to elucidate the role of PPA in glaucoma pathogenesis and a clinical index to take notice for myopic subjects.