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Clinical Sciences
September 1999

Methodological Variations in Estimating Apparent Progressive Visual Field Loss in Clinical Trials of Glaucoma Treatment

Author Affiliations

From the Department of International Health, Johns Hopkins School of Hygiene and Public Health (Dr Katz), and the Dana Center for Preventive Ophthalmology, Wilmer Institute, The Johns Hopkins School of Medicine (Drs Katz, Congdon, and Friedman), Baltimore, Md. The authors have no commercial or proprietary interest in the Humphrey Field Analyzer or in the company that manufactures this product. The authors do not have any financial interest or receive any payment as consultants, reviewers, or evaluators of this product.

Arch Ophthalmol. 1999;117(9):1137-1142. doi:10.1001/archopht.117.9.1137

Objectives  To compare methods to estimate the incidence of visual field progression used by 3 large randomized trials of glaucoma treatment by applying these methods to a common data set of annually obtained visual field measurements of patients with glaucoma followed up for an average of 6 years.

Methods  The methods used by the Advanced Glaucoma Intervention Study (AGIS), the Collaborative Initial Glaucoma Treatment Study (CIGTS), and the Early Manifest Glaucoma Treatment study (EMGT) were applied to 67 eyes of 56 patients with glaucoma enrolled in a 10-year natural history study of glaucoma using Program 30-2 of the Humphrey Field Analyzer (Humphrey Instruments, San Leandro, Calif). The incidence of apparent visual field progression was estimated for each method. Extent of agreement between the methods was calculated, and time to apparent progression was compared.

Results  The proportion of patients progressing was 11%, 22%, and 23% with AGIS, CIGTS, and EMGT methods, respectively. Clinical assessment identified 23% of patients who progressed, but only half of these were also identified by CIGTS or EMGT methods. The CIGTS and the EMGT had comparable incidence rates, but only half of those identified by 1 method were also identified by the other.

Conclusions  The EMGT and CIGTS methods produced rates of apparent progression that were twice those of the AGIS method. Although EMGT, CIGTS, and clinical assessment rates were comparable, they did not identify the same patients as having had field progression.