Abstract
Purpose:
Tilted disc has been reported to be associated with myopia, and it seems to influence on the clinical course and visual field (VF) defect in glaucoma patients. We performed a retrospective, cross-sectional study to find the associated factors including disc tilt related variables that can affect the severity of the visual field defect in normal tension glaucoma (NTG) with myopic tilted disc.
Methods:
We analyzed one hundred twenty-eight NTG patients with myopic tilted disc with different VF defect on both eyes and comparison between both eyes was performed. Numbers of IOP lowering medication were investigated, and optic disc tilt ratio and torsion were measured by disc photography. Temporal and vertical tilt angle were measured using cirrus OCT. The both eyes were divided into two groups according to the severity of VF defect: the more severe VF defect eye and the less severe VF defect eye. The asymmetry of VF defect was defined as the difference of the mean thresholds between the superior and inferior hemifield. Logistic regression analysis was performed to evaluate possibly associated variables including the disc tilt, torsion, temporal and vertical tilt that may be related to the more severe VF defect in NTG with myopic tilted disc. After the analysis, the difference of the VF asymmetry was investigated according to the extent of vertical tilt angle.
Results:
Vertical tilt angle and the number of IOP lowering medication were larger in the more severe (12.6 ± 5.3° and 1.3 ± 0.8) than the less severe VF defect eyes (8.6 ± 5.5° and 0.9 ± 0.8) (P = 0.038; P = 0.003). In multivariate logistic regression analysis, vertical tilt angle and the number of medication was also statistically significant (P = 0.023; P =0.003). When the analysis of the severe VF defect eyes was performed, VF asymmetry was significantly greater in the large vertical tilt angle group than mild and moderate vertical angle tilt groups (P = 0.016; P = 0.042).
Conclusions:
The vertical tilt angle was significantly larger in the more severe VF defect eyes in NTG with myopic tilted disc. In addition, the VF asymmetry was greater in larger vertical tilt angle group. Vertical tilt angle should be considered in the presence of the asymmetrical VF defect on both hemifield in NTG eyes with myopic tilted disc.