Comparison of Superior and Inferior Visual Field Asymmetry Between Normal-tension and High-tension Glaucoma.

Abstract

Increased severity of glaucoma heightened the hemispherical asymmetry in normal-tension and high-tension glaucoma (NTG/HTG), especially NTG. NTG showed localized superior defects in the central and paracentral areas whereas HTG showed mild asymmetry with diffuse defects. The purpose of this study was to compare the patterns of visual field (VF) defects according to glaucoma severity in NTG and HTG. A total of 1458 eyes with NTG (936) and HTG (522) were classified by mean deviation values into mild, moderate, and severe. The mean total deviation (mTD) values for each nasal, central, paracentral, arcuate 1, and arcuate 2 region of the Glaucoma Hemifield Test (GHT) were calculated. The differences in mTD between the superior and inferior hemifields of NTG and HTG were compared, and the degree of hemifield asymmetry was plotted. In NTG and HTG, the mTDs of the 5 regions of the superior GHT were significantly worse than those of the corresponding regions of the inferior GHT at all severity levels except for mild HTG. However, NTG showed significantly greater asymmetry than HTG in 2 regions at mild, 3 at moderate, and all 5 at severe. Moderate and severe NTG showed severe asymmetry with localized superior field defects concentrated at the central and paracentral areas with >8 dB asymmetry. However, in all HTG groups showed mild asymmetry with diffuse defects. The superior hemifield was more severely affected than the inferior hemifield in NTG and HTG. As the severity of glaucoma increased, so did the asymmetry in both groups, with NTG showing more profound asymmetric VF defects in the central and paracentral areas whereas HTG did not. Different VF patterns suggest differing pathologic mechanisms and possible need for different therapeutic strategies in NTG and HTG.