Visual field improvement in the collaborative initial glaucoma treatment study

David C Musch, Brenda W Gillespie, Paul F Palmberg, George Spaeth, Leslie M Niziol, Paul R Lichter, David C Musch, Brenda W Gillespie, Paul F Palmberg, George Spaeth, Leslie M Niziol, Paul R Lichter

Abstract

Purpose: To evaluate critically visual field (VF) improvement in participants in the Collaborative Initial Glaucoma Treatment Study (CIGTS).

Design: Prospective, comparative case series from a randomized clinical trial comparing trabeculectomy and topical medications in treating open-angle glaucoma (OAG).

Methods: A total of 607 subjects with newly diagnosed OAG were identified for study. Baseline and follow-up VF tests were obtained and mean deviation (MD) change from baseline over follow-up was analyzed. Clinically substantial change (loss or improvement) was defined as change from baseline of ≥ 3 decibels in MD. Baseline factors were inspected to determine their association with VF improvement in repeated measures regression models.

Results: The percentage of participants showing substantial VF improvement over time was similar to that showing VF loss through 5 years after initial treatment, after which VF loss became more frequent. Measures of better intraocular pressure (IOP) control during treatment were significantly predictive of VF improvement, including a lower mean IOP, a lower minimum IOP, and lower sustained levels of IOP over follow-up. Other predictive factors included female sex (odds ratio [OR] = 1.73), visits 1 year prior to cataract extraction (OR = 0.11), and an interaction between treatment and baseline MD wherein surgically treated subjects with worse baseline VF loss were more likely to show VF improvement.

Conclusions: In the CIGTS, substantial VF loss and improvement were comparable through 5 years of follow-up, after which VF loss became more frequent. Predictive factors for VF improvement included several indicators of better IOP control, which supports the postulate that VF improvement was real.

Trial registration: ClinicalTrials.gov NCT00000149.

Copyright © 2014 Elsevier Inc. All rights reserved.

Figures

Figure 1
Figure 1
Percent of subjects showing a substantial gain/loss (≥3 dB) in mean deviation from baseline (evaluated at each visit) and percent of subjects showing sustained gain/loss (validated by the next consecutive visit) over 9 years of follow-up in the Collaborative Initial Glaucoma Treatment Study. Standard error bars were calculated assuming estimates from a binomial distribution. Percent gain was significantly different from percent loss at years 7 and 8 (p-values=0.0053 and 0.0088, respectively; test of equality of binomial proportions). dB=decibel.
Figure 2
Figure 2
Interaction plots for the effects of (A) baseline mean deviation and treatment on substantial visual field improvement (increase in mean deviation (MD) of ≥3dB from baseline) and (B) vascular/cardiac disease over time on substantial visual field improvement in the Collaborative Initial Glaucoma Treatment Study. Error bars are ±1 standard error. dB=decibel.
Figure 2
Figure 2
Interaction plots for the effects of (A) baseline mean deviation and treatment on substantial visual field improvement (increase in mean deviation (MD) of ≥3dB from baseline) and (B) vascular/cardiac disease over time on substantial visual field improvement in the Collaborative Initial Glaucoma Treatment Study. Error bars are ±1 standard error. dB=decibel.
Figure 3
Figure 3
Association of intraocular pressure control measures with substantial visual field improvement (increase in mean deviation (MD) of ≥3dB from baseline) in the Collaborative Initial Glaucoma Treatment Study. OR=odds ratio; CI=confidence interval; SD=standard deviation; IOP=intraocular pressure; mmHg=millimeters of mercury; dB=decibel.

Source: PubMed

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