Long-term relationship between intraocular pressure and visual field loss in primary open-angle glaucoma.

Purpose

To investigate the dependence upon intraocular pressure (IOP) of the progression of visual field defects in eyes with primary open-angle glaucoma (POAG), in which the mean IOP was maintained at < or =21 mm Hg.

Methods

This study involved 100 eyes with POAG, which were followed up for > or =5 years. The mean IOP levels were maintained at < or =21 mm Hg during the follow-up period. The relationship between the IOP and the progression of visual field defects, which was scored using the Advanced Glaucoma Intervention Study criteria, was investigated retrospectively.

Results

Compared with the baseline scores, the visual field defect scores had significantly worsened by the end of the follow-up period (P<0.0001, Wilcoxon paired signed rank test). The change in the visual field defect score (2.5+/-0.5) in eyes with average IOP levels of > or =16 mm Hg (n=36) was significantly greater (P=0.031, Mann-Whitney U test) than the change (1.3+/-0.3) in eyes with average IOP levels of <16 mm Hg (n=64). Moreover, IOP of > or =18 mm Hg made a major contribution to the aggravation of visual field defects in eyes with POAG.

Conclusions

Eyes with POAG and with mean IOP levels maintained at < or =21 mm Hg underwent IOP-dependent progression of their visual field defects. Our results suggest that further IOP lowering would be beneficial in such cases.