Elsevier

Ophthalmology

Volume 114, Issue 3, March 2007, Pages 460-465
Ophthalmology

Original Article
Visual Field and Intraocular Pressure Asymmetry in the Low-Pressure Glaucoma Treatment Study

Presented in part at: Association for Research in Vision and Ophthalmology annual meeting, May 4, 2005, Fort Lauderdale, Florida.
https://doi.org/10.1016/j.ophtha.2006.06.056Get rights and content

Objective

To explore the relationship between asymmetric baseline intraocular pressure (IOP) and asymmetric visual field (VF) loss in the Low-Pressure Glaucoma Treatment Study.

Design

Randomized, multicenter, controlled clinical trial.

Participants

Low-pressure glaucoma (LPG) patients 30 years or older were identified. Exclusion criteria included an untreated pressure > 21 mmHg, advanced VF loss, and contraindications to study medications.

Interventions

A baseline VF was created using the average of 2 reliable Humphrey full-threshold examinations. A baseline diurnal IOP curve was performed without IOP-lowering medication.

Main Outcome Measures

Mean diurnal, peak, trough, IOP range (peak − trough), and standard deviation (SD) of IOP measurements, and mean deviation (MD) and corrected pattern SD (CPSD) of VF examinations.

Results

One hundred ninety patients were enrolled (mean age, 64.9±10.7 years). Mean deviation and CPSD were not correlated with mean, peak, trough, or peak minus trough (P − T) IOP (Ps = 0.2–0.9). Among patients with unilateral VF loss (n = 53 [27.9%]), there were no differences (Ps = 0.3–0.9) in any IOP parameter between the normal VF eye and fellow glaucomatous eyes. Among patients with bilateral VF loss (n = 137 [72.1%]), mean, peak, trough, and P − T IOPs were similar in eyes with a better VF MD compared with eyes with a worse VF MD (Ps = 0.2–0.7). Cross-classified contingency tables demonstrated no relationship (Ps = 0.1–0.3) between IOP and VF MD or CPSD using chi-square analysis.

Conclusions

Intraocular pressure asymmetry is unrelated to VF asymmetry in the Low-Pressure Glaucoma Treatment Study, suggesting an unclear pathogenic relationship between IOP and glaucomatous damage in eyes with LPG.

Section snippets

Patients and Methods

Details of the Low-Pressure Glaucoma Treatment Study’s methodology have been reported.15 The null hypothesis being tested is that no differences in VF stability or progression will occur among patients randomized to treatment with brimonidine tartrate 0.2% compared with treatment with timolol maleate 0.5%. The Low-Pressure Glaucoma Treatment Study Group consisted of 13 clinical centers, and the institutional review boards at all participating centers approved the study protocol and informed

Results

One hundred ninety patients (113 women, 77 men) with a mean age of 64.9±10.7 years (range, 37–86) were enrolled in the Low-Pressure Glaucoma Treatment Study. There were 137 patients (72.1%) with bilateral VF loss and 53 patients (27.9%) with unilateral field loss. Seventy-six of 190 patients (40%) were not receiving IOP-lowering medication at the time of the baseline examination. Table 1 illustrates the clinical characteristics of patients with bilateral versus unilateral VF loss. Clinical

Discussion

Contrary to prior reports,1, 2, 3, 14 our data do not demonstrate a relationship between IOP asymmetry and VF asymmetry in LPG. Several factors are worthy of careful consideration to reconcile the Low-Pressure Glaucoma Treatment Study results with prior reports, including differences in study design, patient population, and analysis methods. Prior retrospective studies evaluated nonconsecutive patients, many of whom had both kinetic and static perimetries. As a prospective clinical trial, the

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Manuscript no. 2006-227.

None of the authors has any financial interest in drugs or devices described in the article.

Supported by Allergan, Inc., Irvine, California (unrestricted grant to Low-Pressure Glaucoma Study Group); the Steven and Shelley Einhorn Research Fund of the New York Glaucoma Research Institute, New York, New York; and the Chicago Center for Vision Research, Chicago, Illinois.

Study Group members are listed in “Appendix.”

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