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R. Sood, T.C. Chen; Evaluation of the Diagnostic Accuracy of Scanning Laser Polarimetry in Glaucomatous and Ocular Hypertensive Eyes . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3416.
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Purpose: To evaluate the ability of 13 GDx parameters to discriminate glaucomatous and ocular hypertensive eyes from normal eyes. Analysis was also done to determine if GDx parameters could accurately localize known visual field defects. Methods: We did a retrospective chart review of patients seen at the Massachusetts Eye and Ear Infirmary Glaucoma Service. Patients were included if they had GDx nerve fiber layer analysis as well as reliable standard Humphrey 24-2 visual field testing. Eyes were classified as normal, ocular hypertension (ie. pressure > 22 mmHg without optic disc abnormalities or visual field defects), and open angle glaucoma (ie. optic nerve damage with characteristic visual field loss). Eyes with glaucomatous visual field defects limited to only one hemifield were selected for further analysis using only parameters specific to the affected retinal nerve fiber layer (RNFL) area. Sensitivity and specificity of the 13 GDx parameters were calculated, defining parameters as abnormal at the 90% (P ≤ 10.0%) and 95% (P ≤ 5.0%) confidence limits. Results: There were 260 eyes (108 normal; 76 glaucomatous; 76 ocular hypertensive) of 166 patients. The parameters with the highest sensitivities for predicting glaucomatous eyes were superior maximum (50% [P ≤ 10.0%]) and superior average (35.5% [P ≤ 5.0%]), and mean sensitivities for all 13 parameters were 37.3% ± 9.1 (P ≤ 10.0%) and 22.6% ± 9.1 (P ≤ 5.0%). The parameter with the highest sensitivity for predicting ocular hypertension was maximum modulation (38.2% [P ≤ 10.0%]; 21.1% [P ≤ 5.0%]), and mean sensitivities were 26.5% ± 5.3 (P ≤ 10.0%) and 14.0% ± 4.4 (P ≤ 5.0%). For all parameters, specificities were higher compared to sensitivities. For patients with defects limited to the inferior field, the highest sensitivity obtained was for superior maximum (61.1% [P ≤ 10.0%]), and mean sensitivities for this group were 50.9% ± 7.4 (P ≤ 10.0%) and 36.1% ± 11.5 (P ≤ 5.0%). For patients with defects limited to the superior field, the highest sensitivities were for inferior average and inferior maximum (both 30.0% [P ≤ 10.0%]); inferior average only (30.0% [P ≤ 5.0%]), and mean sensitivities were 20.8% ± 10.7 (P ≤ 10.0%) and 18.3% ± 11.7 (P ≤ 5.0%). Conclusions: The sensitivities of GDx parameters are much lower than previously reported. Single parameter analysis suggests that SLP can not accurately diagnose eyes with clear glaucomatous field defects. Known localized glaucomatous visual field defects also correlated poorly with location specific RNFL thinning (as detected by GDx).
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