Elsevier

Ophthalmology

Volume 114, Issue 2, February 2007, Pages 205-209
Ophthalmology

Original Article
Fluctuation of Intraocular Pressure and Glaucoma Progression in the Early Manifest Glaucoma Trial

https://doi.org/10.1016/j.ophtha.2006.07.060Get rights and content

Purpose

To investigate whether increased fluctuation of intraocular pressure (IOP) is an independent factor for glaucoma progression.

Design

A cohort of patients was followed up in a randomized clinical trial.

Participants

Two hundred fifty-five glaucoma patients from the Early Manifest Glaucoma Trial (EMGT; 129 treated and 126 control patients).

Methods

Study visits, conducted every 3 months, included ophthalmologic examinations, IOP measurements, and standard automated perimetry, with fundus photography every 6 months. Intraocular pressure values were included only until the time of progression in those eyes that showed such progression. Individual mean follow-up IOP and IOP fluctuation, calculated as the standard deviation of IOP at applicable visits, were the variables of main interest. Cox regression with time-dependent variables was used to evaluate the association between IOP fluctuation and time to progression, both with and without IOP mean in the models. These analyses also controlled for other significant variables.

Main Outcome Measures

Glaucoma progression, as defined by a predetermined visual field criterion, worsening of the disk, assessed by an independent disc reading center, or both.

Results

Median follow-up time was 8 years (range, 0.1–11.1 years). Sixty-eight percent of the patients progressed. When considering mean follow-up IOP and IOP fluctuation in the same time-dependent model, mean IOP was a significant risk factor for progression. The hazard ratio (HR) was 1.11 (95% confidence interval [CI], 1.06–1.17; P<0.0001). Intraocular pressure fluctuation was not related to progression, with an HR of 1.00 (95% CI, 0.81–1.24; P = 0.999).

Conclusions

These results confirm our earlier finding that elevated IOP is a strong factor for glaucoma progression, with the HR increasing by 11% for every 1 mmHg of higher IOP. Intraocular pressure fluctuation was not an independent factor in our analyses, a finding that conflicts with some earlier reports. One explanation for the discrepancy is that our analyses did not include postprogression IOP values, which would be biased toward larger fluctuations because of more intensive treatment. In contrast, in this EMGT report, no changes in patient management occurred during the period analyzed.

Section snippets

Overview

The EMGT design and methods have been described in detail elsewhere15 and are here summarized. Patients with newly detected, previously untreated glaucoma, including primary open-angle glaucoma, normal-tension glaucoma, and exfoliation glaucoma, were recruited. Eligible patients were between 50 and 80 years of age with reproducible glaucomatous visual field loss in at least 1 eye, but no advanced visual field loss, that is, mean deviation values better than −16 decibels, visual acuity equal to

Results

At data closure on March 31, 2004, the median follow-up time was 8 years (range, 0.1–11.1 years). Data from all 255 patients originally enrolled in the EMGT were included in the current analyses. Sixty-eight percent of the patients had progressed, with 59% of treated and 76% of control patients progressing. All patients in the control group remained untreated until reaching the outcome of glaucoma progression. The mean follow-up IOP was 19.5 mmHg for those who progressed and 16.5 mmHg for those

Discussion

Our results continue to support our earlier conclusions regarding the effect of the magnitude of IOP on glaucoma progression,4, 14 and we were unable to demonstrate any effect of increased IOP fluctuation on glaucoma progression. In fact, our results yielded no significant relationship between higher IOP fluctuation and glaucoma progression.

Just as in the AGIS report,13 we used the standard deviation of follow-up IOP measurements as a surrogate for IOP fluctuation, because no diurnal tension

References (17)

There are more references available in the full text version of this article.

Cited by (0)

Manuscript no. 2006-453.

The Early Manifest Glaucoma Trial was supported by the National Eye Institute, Bethesda, Maryland (grant nos. U10EY10260, U10EY10261), and Swedish Research Council, Stockholm, Sweden.

None of the authors has any conflicts of interest related to the article.

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