Influence of initial visual field sensitivity on visual field loss progression in open angle glaucoma

INTRODUCTION: It is important to know the risk factors for visual field defect progression in order to predict the future development of glaucoma. OBJECTIVE: To investigate the influence of visual field initial sensitivity on the rate of visual field progression. METHODS: A minimum of five visual fields were performed using computerized perimetry (Octopus) over a mean followup 4-year period (48.85 +/- 17.84 months) in 64 persons (114 eyes) with primary open angle glaucoma. The rate of change of the whole central visual field and each of the seven regions of the field were measured by linear regression analysis of the mean sensitivity value versus time. Based on the slope of the regression line of visual field mean sensitivity over time the eyes were divided into two groups: the group with stable and the group with progressive visual field.The comparison of the mean sensitivity of the whole central visual field between the groups was performed using the Mann-Whitney U-test. The Spearman rang correlation coefficient and the Spearman probability p values were calculated to assess the mean sensitivity of the whole central visual field and of each visual field regions determined at the beginning of the study. RESULTS: The initial mean sensitivity of the whole central visual field was lower in the group with progressive visual field (16.62 +/- 6.35 dB). Correlation between the initial mean sensitivity and the slope of the regression line was negative. The lowest mean sensitivity was in the group with progressive visual field in the upper temporal (13.73 +/- 7.35 dB), nasal (14.74 +/- 7.23 dB) and upper nasal (15.03 +/- 7.75 dB) regions. CONCLUSION: The lower mean sensitivity value of the visual field, especially in the nasal and upper nasal visual field regions, carries a greater risk for delayed progressive loss of the visual field in persons with glaucoma.