Optic Nerve Morphology Influences Structure-Function Relationship in Early Glaucoma With and Without High Myopia

The purpose of this study was to determine the influence of optic nerve head (ONH) rotation and tilt on the structure-function (S-F) relationship differences between early open-angle glaucoma (OAG) with and without high myopia (HM).

A total of 164 eyes, including 69 early highly myopic glaucoma (HMG) eyes, 60 early OAG eyes, and 35 healthy HM eyes, were included. All the eyes underwent spectral-domain optical coherence tomography, standard automated perimetry, and fundus photography simultaneously. S-F relationships were analyzed by comparing the peripapillary retinal nerve fiber layer thickness (pRNFLT) to the corresponding visual field sensitivity loss (VFSL) according to the Garway-Heath map. Linear regression analyses were used to evaluate the relationship between ONH rotation and tilt with pRNFLT and VFSL.

Multivariate regression analysis demonstrated that the ovality index was associated with nasal (P = 0.014) pRNFLT in OAG eyes and with nasal (P < 0.001), temporal (P = 0.012), and superior nasal (P = 0.015) pRNFLT in healthy HM eyes, but not in HMG eyes. Moreover, ONH rotation was significantly associated with inferior nasal (P = 0.013) pRNFLT in HMG eyes and with inferior temporal (P = 0.029) and inferior nasal (P = 0.036) pRNFLT in healthy HM eyes, whereas no associations were observed in OAG eyes. The strongest relationship between pRNFLT and VFSL for HMG and OAG were found in the inferior temporal (R = 0.567) and superior temporal sector (R = 0.638), respectively. However, no significant relationships were observed in healthy HM eyes (all P > 0.05).

Optic disc rotation and tilt may affect the distribution of the pRNFL in HM eyes with or without glaucoma, resulting in abnormal correspondence between structure and function. The analysis of the S-F relationship in the inferior temporal sector could be a valuable factor in assessing HMG eyes.