Objective: To evaluate the association of long-term intraocular pressure (IOP) fluctuation and visual field (VF) progression in patients with glaucoma and low IOP.
Methods: Four hundred eight eyes with IOPs below 18 mm Hg after a triple procedure (phacoemulsification, posterior chamber intraocular lens implantation, and trabeculectomy) were included in this study. Measurements of IOP and VF were taken for at least 3 years after surgery. Based on the SD in postoperative IOPs, the sample was split into 2 groups (group 1: SD<or=2; group 2: SD>2). Change in VF at each test location was defined as a change in threshold sensitivity of 1 dB per year or higher, with P<or=.01; pointwise linear regression analysis was applied.
Main outcome measures: Intraocular pressure and VF progression.
Results: The groups showed no differences in IOPs through the follow-up period and in the VF defect score 3 months after surgery. After 13 years, more patients with progressive VF deterioration were detected in group 2 than in group 1.
Conclusion: Our results showed that larger long-term IOP fluctuation was associated with a progressive increase in the VF deterioration even though patients with glaucoma maintained their IOPs after the triple procedure.
Application to clinical practice: The SD of long-term IOP should be less than 2 in patients with glaucoma, even if their IOPs drop below 18 mm Hg.
Trial registration: clinicaltrials.gov Identifier: NCT00428740.