Abstract
BACKGROUND: To investigate the impact of optic disc torsion (ODT), horizontal disc tilt (HDT) angle, and ovality index (OI) on different retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) segments in healthy myopic eyes. METHODS: ODT and OI were measured from fundus photographs. HDT angle, peripapillary RNFL, and macular GCIPL were measured by swept-source optical coherence tomography (SS-OCT). The association between optic disc morphology and the RNFL/GCIPL thickness were evaluated, with age and axial length (AL) adjusted. RESULTS: Among 530 healthy myopic eyes of 284 participants (mean age: 41.7 years, mean spherical equivalent: - 7.70 D, and mean AL: 26.6 mm), 335 eyes (63.2%) had temporal disc torsion (temporal group) and 195 eyes (36.8%) had nasal disc torsion (nasal group). For the nasal group, a larger OI was associated with thinner superior-to-superonasal GCIPL (β = - 7.465 to - 6.972, both P = 0.024) and temporal RNFL sectors (β = - 49.596 to - 27.748, P ≤ 0.014). For the temporal group, a larger OI was associated with thinner superior-to-nasal (β = - 50.255 to - 22.093, P ≤ 0.006) and thicker temporal RNFL sectors (β = 29.015 to 56.890, P ≤ 0.003). Additionally, a larger HDT angle was associated with thinner superior-to-nasal RNFL sectors (β = - 0.559 to - 0.242, P ≤ 0.036) and thinner superior-to-superotemporal GCIPL sectors (β = - 0.084 to - 0.069, P ≤ 0.037). CONCLUSIONS: The optic disc tortional direction was associated with the measurement of different RNFL and GCIPL sectors independent of the AL and age. These should be considered when constructing a myopic normative database.