Baseline mean deviation and rates of visual field change in treated glaucoma patients.

PURPOSE

To evaluate the relationships between baseline visual field (VF) mean deviation (MD) and subsequent progression in treated glaucoma.

METHODS

Records of patients seen in a glaucoma practice between 1999 and 2009 were reviewed. Patients with glaucomatous optic neuropathy, baseline VF damage, and ≥8 SITA-standard 24-2 VF were included. Patients were divided into tertiles based upon baseline MD. Automated pointwise linear regression determined global and localized rates (decibels (dB) per year) of change. Progression was defined when two or more adjacent test locations in the same hemifield showed a sensitivity decline at a rate of >1.0  dB per year, P<0.01.

RESULTS

For mild, moderate, and severe groups, progression was noted in 29.5, 31.2, and 26.0% of eyes (P=0.50) and global rates of VF change of progressing eyes were -1.3±1.2, -1.01±0.7, and -0.9±0.5 dB/year (P=0.09, analysis of variance). Within these groups, intraocular pressure (IOP) in stable vs progressing eyes were 15.5±3.3 vs 17.0±3.1 (P<0.01), 15.4±3.3 vs 15.9±2.5 (P=0.28), and 14.0±2.8 vs 14.8±2.3 mm Hg (P=0.07). More glaucoma filtering surgeries were performed in eyes with worse MD. There was no significant difference between groups regarding their risk of progression in both univariate (P=0.50) and multivariate (P=0.26) analyses adjusting for differences in follow-up IOP.

CONCLUSIONS

After correcting for differences in IOP in treated glaucoma patients, we did not find a relationship between the rate of VF change (dB per year) and the severity of the baseline VF MD. This finding may have been due to more aggressive IOP lowering in eyes with more severe disease. Eyes with lower IOP progressed less frequently across the spectrum of VF loss.