Factors Related to Superior and Inferior Hemifield Defects in Primary Open-Angle Glaucoma

PURPOSE: We aimed to investigate factors related to superior and inferior hemifield defects in primary open-angle glaucoma (POAG). METHODS: Sixty-seven subjects with newly diagnosed, untreated POAG underwent optical coherence tomography (OCT) of the disc area, macular ganglion cell complex (mGCC), and circumpapillary retinal nerve fiber layer (cpRNFL) thickness within 6 months of the visual field (VF) test. Based on the VF and OCT results, 40 subjects had a superior and 27 an inferior hemifield defect. Clinical data including visual acuity, refractive error, disc hemorrhage, VF indexes, and medical history were recorded. RESULTS: Average mGCC thickness corresponding to the defective hemifields was thinner in the superior VF defect group than in the inferior VF defect group (P=0.003). Average total deviation (TD) was comparable between the two groups. However, the superior VF defect group had a higher prevalence of defects (P=0.001) and lower TD (P=0.002) within central 5 degrees of VF than the inferior VF defect group. In multivariate regression analyses, the temporal-lower and inferior-temporal cpRNFL thicknesses were significant contributing factors to the inferior mGCC thickness in the superior VF defect group. In the inferior VF defect group, the disc area, family history of glaucoma, and temporal-upper cpRNFL thickness contributed to the superior mGCC thickness. CONCLUSION: The inferior mGCC thickness corresponding to the superior hemifield defect group was significantly thinner than the superior mGCC thickness corresponding to the inferior hemifield defect group. The factors related to the reduction of the corresponding mGCC thickness may differ between superior VF defect and inferior VF defect groups.