Glaucoma monitoring in a clinical setting: Glaucoma progression analysis vs nonparametric progression analysis in the Groningen longitudinal glaucoma study

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 (κ=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 κ=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.

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