Structural Features of Optic Nerve Head in Glaucoma with Single-hemispheric and Bi-hemispheric Visual Field Defects

Purpose: To compare the structural features of the optic nerve head (ONH) in moderate glaucoma patients with single-hemispheric and bi-hemispheric visual field (VF) defects.Methods: Patients with open-angle glaucoma (OAG) and a VF mean deviation between -6 and -12 dB were retrospectively enrolled. Based on VF defect patterns, eyes were classified into two groups: those with single-hemispheric VF defects and those with bi-hemispheric VF defects. Structural features analyzed included Bruch’s membrane opening area, lamina cribrosa (LC) thickness, temporal β-zone parapapillary atrophy with and without Bruch's membrane (βPPA<sub>+BM</sub>, βPPA<sub>-BM</sub>, respectively), and peripapillary retinal nerve fiber layer thickness using spectral-domain optical coherence tomography.Results: Out of 137 eyes from 124 patients, 80 eyes had single-hemispheric VF defects and 57 eyes had bi-hemispheric VF defects. The bi-hemispheric group exhibited longer axial length (<i>p</i> = 0.038), thinner central corneal thickness (<i>p</i> = 0.003), thinner LC (<i>p</i> < 0.001), and larger temporal βPPA<sub>+BM</sub> (<i>p</i> = 0.002) compared to the single-hemispheric group.Conclusions: Among Korean OAG patients with moderate VF defects, those with bi-hemispheric VF defects showed more structurally vulnerable optic discs characterized by longer axial lengths, thinner central corneal thickness, thinner LC, and larger β PPA+BM compared to those with single-hemispheric VF defects. These findings underline the importance of evaluating ONH structures in monitoring glaucoma progression particularly in patients with extensive VF damage.