Elsevier

Ophthalmology

Volume 108, Issue 11, November 2001, Pages 1943-1953
Ophthalmology

Interim clinical outcomes in the collaborative initial glaucoma treatment study comparing initial treatment randomized to medications or surgery☆

https://doi.org/10.1016/S0161-6420(01)00873-9Get rights and content

Abstract

Purpose

To report interim outcome data, using all available follow-up through 5 years after treatment initiation, in the Collaborative Initial Glaucoma Treatment Study (CIGTS).

Participants

Six hundred seven newly diagnosed glaucoma patients.

Methods

In a randomized clinical trial, 607 patients with newly diagnosed open-angle glaucoma were initially treated with either medication or trabeculectomy (with or without 5-fluorouracil). After treatment onset and early follow-up, patients were evaluated clinically at 6-month intervals. In addition, quality of life telephone interviews were conducted at similar frequency to the clinical visits. Patients in both arms of CIGTS were treated aggressively in an effort to reduce intraocular pressure (IOP) to a level at or below a predetermined target pressure specific for each individual eye. Visual field (VF) scores were analyzed by time-specific comparisons and by repeated measures models.

Main outcome measures

VF loss was the primary outcome variable in CIGTS. Secondary outcomes of visual acuity (VA), IOP, and cataract were also studied.

Results

On the basis of completed follow-up through 4 years and partially completed through 5 years, VF loss did not differ significantly by initial treatment. Over the entire period of follow-up, surgical patients had a greater risk of substantial VA loss compared with medical patients. However, by 4 years after treatment, the average VA in the two groups was about equal. Over the course of follow-up, IOP in the medicine group has averaged 17 to 18 mmHg, whereas that in the surgery group averaged 14 to 15 mmHg. The rate of cataract requiring removal was greater in the surgically treated group.

Conclusions

Both initial medical or initial surgical therapy result in about the same VF outcome after up to 5 years of follow-up. VA loss was greater in the surgery group, but the differences between groups seem to be converging as follow-up continues. When aggressive treatment aimed at substantial reduction in IOP from baseline is used, loss of VF can be seen to be minimal in general. Because 4 to 5 years of follow-up in a chronic disease is not adequate to draw treatment conclusions, these interim CIGTS outcomes do not support altering current treatment approaches to open-angle glaucoma.

Section snippets

Patients and methods

Enrollment took place at 14 clinical centers from October 1993 through April 1997. Each clinical center and the study operations centers (administrative, coordinating, and quality of life) received institutional review board approval for the study. Eligible patients must have had (1) newly diagnosed open-angle glaucoma (primary, pseudoexfoliative, and pigmentary forms) in one or both eyes; (2) one of three combinations of qualifying IOP, VF changes, and optic disc findings; (3) a best-corrected

Results

Fourteen clinical centers screened 1190 subjects for enrollment from October 1993 through April 1997. Of those screened, 728 (61%) were found to be eligible to participate. Six hundred seven (83%) of these eligible patients agreed to participate, and the remaining 121 (17%) decided against participation. The latter patients were older than those who agreed to participate. Reasons for refusal included concerns regarding surgery (n = 43, 36%), study burden (n = 28, 23%), lack of interest (n = 21,

Discussion

When the CIGTS was organized, studies in England and Scotland16, 17 suggested that early trabeculectomy was preferable to treatment with medication to prevent progression of VF loss. The authors attributed differences in VF progression to the extent of IOP control, which was best in the surgery group. It seems that the patients in the British studies may have had more advanced glaucoma than did our patients, which could account for greater visual field progression in a shorter period of time

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    ☆

    The CIGTS is funded by the National Institutes of Health, National Eye Institute, Bethesda, Maryland, grant numbers EY09100, EY09140, EY09141, EY09142, EY09143, EY09144, EY09145, EY09148, EY09149, EY09150, and EY09639.

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    Copyright © 2001 American Academy of Ophthalmology, Inc. Published by Elsevier Inc. All rights reserved.