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S Kremmer, HD Ayertey, JM Selbach, KP Steuhl; Diagnosis of Glaucomatous Retinal Nerve Fiber Bundle Defects by Means of a New Sector-Analysis Software for Scanning Laser Polarimetry (GDx) . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1012.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: In the diagnosis of glaucomatous nerve fiber defects, red-free photography has been established since many years as a standard procedure. In the last years, scanning laser polarimetry (SLP) has become more and more important in the detection of diffuse nerve fiber loss. Because of the difficulties in the detection of localized retinal nerve fiber layer (RNFL) defects (slit defects) we evaluated a new sector-analysis software (SAS). Method: The following examinations were performed at 150 glaucoma patients (POAG:n=74, mean 63.9 years; NTG:n=76, mean 64 years): standard ophthalmologic examinations including automated perimetry, RNFL photography (NFP) and SLP (GDx, software version 2.0.10E, Laser Diagnostic Technologies Inc., CA). We evaluated small localized retinal nerve fiber bundle defects. In the new SAS the superior and inferior hemispheres are divided into 14 sectors. For each sector the probability of a localized RNFL loss is given in 5 stages (p10%). Results: In POAG, 6 localized RNFL defects could be detected in NFP (5/6 in the inferior hemisphere and 1/6 in the superior hemisphere) and 11 in SLP (6/11 in the inferior hemisphere and 5/11 in the superior hemisphere); they agreed in 5 patients. In NTG, 9 localized RNFL defects were found in NFP (4/9 in the upper and 5/9 in the lower hemisphere) and 10 in SLP (5/10 in the upper and in the lower hemisphere). In POAG-patients, 2/11 localized defects found in SLP correlated with the new SAS and in NTG-patients 1/10, respectively. All other localized RNFL defects found in the standard SLP were not detected by SAS, which only revealed minor deviation from normal (p≷10%). Conclusion: In clinical practice, SLP has advantages in comparison to NFP because a higher rate of good quality images can be obtained and pupils have not to be dilated. Additionally, SLP measurements provide quantitative data and a large normative data base exists. In several cases where retinal nerve fibers are still visible in NFP and SLP, the new SAS shows a severe deviation from normal (p10%) is shown in the new SAS. The new SAS was not able to prove the existence of detected localized RNFL defects found in SLP and seems to have difficulties to evaluate severe RNFL defects which have a thickness similar to the papillo-macular bundle. These defects are not detected as loss. Therefore, we feel that the new SAS has no advantages in comparison to the standard SLP.
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