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L. M. Alencar, G. Vizzeri, R. N. Weinreb, C. Bowd, L. M. Zangwill, P. A. Sample, F. A. Medeiros; Agreement for Detecting Glaucomatous Change Using the GDx VCC Scanning Laser Polarimeter, Standard Automated Perimetry and Stereophotograph Assessment. Invest. Ophthalmol. Vis. Sci. 2008;49(13):741.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the ability of Scanning Laser Polarimetry (GDx VCC) nerve fiber layer analysis in detecting glaucomatous progression, and to compare with Standard Automated Perimetry (SITA SAP) and stereophotograph assessment.
This study enrolled a cohort of glaucoma patients and glaucoma suspects selected from the Diagnostic Innovations in Glaucoma Study (DIGS), who had ≥ 3 good quality GDx exams, ≥ 1 year of follow-up, routine visual fields (VF) and stereophotographs. In total, 1196 examinations were obtained in 249 eyes of 145 individuals during an average GDx follow-up time of 48.7 ± 9.8 months. Change was assessed comparing each visit’s parameters with the baseline. We defined progression when the change in GDx parameters’ values was above the expected long-term variability. Long-term variability estimates (95% specificity) were obtained from the analysis of a separate group of 31 patients suspected of having glaucoma followed untreated for an average of 9.1 ± 3.2 years and who did not develop any evidence of visual field loss or progressive optic nerve damage. Progression by VF was assessed using the Glaucoma Progression Analysis (GPA); and by stereophotographs was assessed comparing the latest photo with the baseline.
Nine eyes progressed only by VF, 14 eyes only by optic disc changes in the stereophotographs, and 6 eyes by both methods. From these 29 eyes, 8 had progression in at least one GDx parameter. However, 52 eyes showed progression with at least one GDx parameter but no changes in VF or photographs.
RNFL longitudinal analysis with the GDx detects more change over time than SAP or stereophotograph assessment. These results might suggest increased sensitivity compared to SAP and photograph assessment, however, further follow-up is necessary to confirm these findings. Poor agreement among the three methods suggests that these techniques might be evaluating different features of glaucoma progression.
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