Background: To detect differences in retinal nerve fiber layer (RNFL) measurements in absolute, advanced and early glaucoma with scanning laser polarimetry (The Nerve Fiber Analyzer GDx), and to assess the usefulness and limitations of this technique for longitudinal follow-up of glaucoma patients.
Methods: This is a prospective, cross-sectional study. Twenty-one eyes of 21 patients with absolute glaucoma, twenty-six eyes of 26 patients with advanced glaucoma and twenty-four eyes of 24 patients with early glaucoma were imaged using scanning laser polarimetry. The twelve standard GDx measurement parameters were compared using ANOVA (analysis of variance) and the Tukey test.
Results: No significant differences were demonstrated for any of the twelve GDx measurement parameters between absolute and advanced glaucoma cases. There were significant differences for some GDx parameters, including the GDx number (p < 0.0001) superior ratio (p < 0.0001), inferior ratio (p < 0.0001), superior/nasal ratio (p < 0.0001), maximum modulation (p < 0.0001), ellipse modulation (p < 0.0001) and inferior average (p = 0.001) between early and advanced glaucoma, and, between early and absolute glaucoma. Significant differences were demonstrated for the superior average (p = 0.01) parameter between early and absolute glaucoma, but not between early and advanced glaucoma.
Conclusions: For follow-up of glaucoma progression, RNFL measurements using scanning laser polarimetry are more useful in the early stage than in the advanced stage.