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K. Mohammadi, L.M. Zangwill, C. Bowd, F. Medeiros, C.C. Berry, R.N. Weinreb; Change over Time in GDx Nerve Fiber Analyzer Measurements in Eyes that Develop Repeatable Glaucomatous Visual Fields . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3365.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare changes in GDx retinal nerve fiber layer (RNFL) measurements over time among eyes that developed repeatable glaucomatous visual fields, and eyes that did not develop repeatable glaucomatous visual fields. Methods: 82 glaucoma suspects with normal appearing visual fields at baseline and at least 3 years of follow-up were included in the study. GDx imaging and visual field testing were completed annually. Measurements from baseline GDx RNFL images were subtracted from measurements from the most recent GDx RNFL images. These values were compared in eyes that developed repeatable visual field damage (convert eyes) and eyes that did not develop repeatable visual field damage (non-convert eyes). Results: 22 (27%) eyes converted by visual fields (mean follow up of 5.1 years) and 61(73%) did not convert (mean follow up of 4.4 years). Of 10 examined GDx parameters, Ellipse Modulation, Max Modulation, and UCSD Linear Discriminant Function had significantly lower baseline values in converts than non-converts (P=0.005). Temporal Average had a significantly higher baseline value in converts (P=0.02.) No other parameters differed significantly at baseline between converts and non-converts. A larger reduction in GDx RNFL thickness parameters was observed in converts compared to non-converts for means of the following parameters (95% CI) (all P≤0.05): Superior Maximum [-9.7 (-15.1, -4.2) vs. -4.2 (-6.9, -1.6)] for converts and non-converts, respectively; Temporal Average [-6.8 (-11.6, -2.0) vs. -0.4 (-0.03, 0.03)]; and Average Thickness [-4.9 (-7.5, -2.2) vs. -1.7 (-3.3, -0.1)]. Mean change in UCSD Linear Discriminant Function was -0.002 (-0.3, 0.3) for converts and -0.4 (-0.6, -0.2) for non-converts (P=0.014). Ellipse Modulation decreased more in non-convert eyes [-0.01 (-0.3, 0.2) for converts and -0.4 (-0.5, -0.2) for non-converts (P=0.01)]. Changes in Superior Average, Inferior Maximum, Inferior Average, Maximum Modulation, and Ellipse Average were not significantly different between converts and non-converts. Conclusions: Glaucomatous changes over time in some examined GDx parameters were significantly larger in convert compared to non-convert eyes. It appears possible to employ the GDx to monitor glaucomatous progression in patients with normal baseline visual field. Further studies are needed to address this issue.
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