Visual Field Characteristics and the Factors That Affect Them in Different Stages of Acute Primary Angle Closure Glaucoma

Objective: To investigate the characteristics of visual field defects in different stages of acute primary angle closure glaucoma (APACG) and determine the factors that affect them. Methods: Patients with APACG were consecutively recruited in this case-control study from September 2015 to September 2016. According to the clinical features, the affected eyes were staged into three groups: preclinical, remission, and chronic. Age- and gender-matched healthy adults were included as normal controls. The clinical data of all subjects were recorded, and visual field tests using the Humphrey Ⅱ 750 perimeter with 30-2 SITA-Standard full threshold strategy were performed in all subjects. The clinical and visual field data of all groups, including mean deviation of visual field (MD), visual field index (VFI) and pattern standard deviation of visual field (PSD) were compared and correlations among them were explored. The data were analyzed by Pearson correlation, Chi-square test, independent samples t test, ANOVA, Kruskal-Wallis test. Results: Twenty normal controls (20 eyes) and 74 APACG patients (74 eyes) were recruited. Among APACG patients, 24 were in the preclinical group, 28 were in the remission group, and 22 were in the chronic group. There were no significant differences in age or gender among the four groups. Comparisons of MD and VFI of all groups showed that the MD and VFI of chronic group were the worst among all groups (P<0.008), and the MD and VFI of remission group were significantly worse than the normal controls (P<0.008). Comparison of PSD of all groups showed that the PSD of chronic group was the largest among all groups (P<0.008), and the PSD of remission group and preclinical group were larger than the normal controls (P<0.008). The MD and VFI of the remission group were negatively correlated with duration of the acute attacks (r=-0.653, P<0.001; r=-0.547, P=0.003), while PSD was positively correlated with duration of the acute attacks (r=0.579, P=0.001). The MD and VFI of the chronic group were negatively correlated with the duration of acute attacks (r=-0.441, P=0.044; r=-0.531, P=0.011) and the cup to disc ratio (r=-0.632, P=0.002; r=-0.633, P=0.002). The MDs and VFIs in the remission group in which the duration of the acute attacks lasted less than 7 days were better than those in which the attacks lasted more than 7 days (Z=-2.998, P=0.003; Z=-2.639, P=0.008). Conclusions: Visual field defects can occur after APACG attacks, and the severity of the defects was associated with duration of the attacks. Shortening the duration of acute attacks could reduce visual field defects. Key words: acute primary angle closure glaucoma; disease course; visual field; affecting factor