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Glaucoma Progression Analysis vs Nonparametric Progression Analysis in the Groningen Longitudinal Glaucoma Study

Christiaan Wesselink, MD; Govert P. Heeg, MD, PhD; Nomdo M. Jansonius, MD, PhD

Arch Ophthalmol. 2009;127(3):270-274.

Objective  To compare prospectively 2 perimetric progression detection algorithms for glaucoma, the Early Manifest Glaucoma Trial algorithm (glaucoma progression analysis [GPA]) and a nonparametric algorithm applied to the mean deviation (MD) (nonparametric progression analysis [NPA]).

Methods  Patients with a reproducible glaucomatous visual field defect at baseline in at least 1 eye were followed up prospectively using perimetry (Humphrey field analyzer 30-2 Swedish interactive thresholding algorithm). Classifications by GPA and by NPA at the end of the follow-up period were compared.

Results  Two hundred twenty-one patients met the inclusion criteria; 1 eye per patient was analyzed. On average, 7.1 reliable fields were available after a mean follow-up period of 5.3 years. The mean MD at baseline was –9.4 dB; the mean MD slope during the follow-up period was –0.25 dB/y. Fifty-six eyes showed progression by GPA and 89 eyes by NPA (P < .001); 42 eyes showed progression by both techniques ( = 0.39). In eyes with progression detected by NPA only, baseline MD was worse than that in eyes with progression detected by GPA (–12.5 vs –8.2 dB, P = .002), and GPA more often gave a reading of "baseline MD out of range" (P < .001). After exclusion of eyes with baseline MD out of range, the measure of agreement was  = 0.50.

Conclusions  Nonparametric progression analysis had fairly good agreement with GPA. Especially in cases of more advanced disease, NPA labeled more eyes as having progression than GPA.

Author Affiliations: Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen (Drs Wesselink, Heeg, and Jansonius), and Department of Epidemiology and Biostatistics, Erasmus Medical Center, Rotterdam (Dr Jansonius), the Netherlands.

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