Interocular Asymmetry of the Visual Field Defects in Newly Diagnosed Normal-tension Glaucoma, Primary Open-angle Glaucoma, and Chronic Angle-closure Glaucoma

Abstract

To compare the interocular asymmetry of visual field loss in newly diagnosed normal-tension glaucoma (NTG), primary open-angle glaucoma (POAG), and chronic angle-closure glaucoma (CACG) patients. Visual field results of 117 newly diagnosed, treatment-naive glaucoma patients (42 NTG, 38 POAG, and 37 CACG) were studied retrospectively. The following 3 visual field defect parameters were used to evaluate the interocular asymmetry: (1) global indices; (2) local mean deviations (MDs) of 6 predefined visual field areas; and (3) stage designated by glaucoma staging system 2. The differences of the above parameters between the trial eye (the eye with greater MDs) and the fellow eye in each subject were defined as interocular asymmetry scores. Interocular asymmetry of visual field loss was presented in all the 3 groups (all P<0.05). CACG group had greater total MD interocular asymmetry score compared with the NTG and POAG groups (among groups, P=0.008; NTG vs. CACG, P=0.005; POAG vs. CACG, P=0.009). CACG also presented with significantly higher local MD interocular asymmetry scores at central, inferior, and temporal areas compared with those of the POAG group and at inferior area compared with that of NTG group. No significant difference in either total or local MDs was detected between NTG and POAG (all P>0.05). Interocular asymmetry scores of glaucoma staging system 2 had no significant difference among the 3 groups (P=0.068). All CACG, POAG, and NTG groups presented with interocular asymmetric visual field loss at the time of diagnosis. CACG had greater interocular asymmetry compared with NTG and POAG. No significant interocular asymmetry difference was observed between NTG and POAG.