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Background: Scanning laser polarimetry (SLP) is a method that enables quantitative assessment of retinal nerve fibre layer (RNFL) thickness surrounding the optic nerve. The commercially available device GDx (GDx, Laser Diagnostics Technologies, San Diego, CA) yields an outprint consisting of a reflectance image, colour-coded retardation map, and the 14 parameters, of which the »Number« was shown to be the single best parameter to discriminate between glaucomatous and normal eyes. The »Number« is a probability score, ranging from 1 (low probability of glaucoma) to 100 (high probability of glaucoma). In our study we determined the sensitivity and the specificity of the »Number« at cutoff values of 23 and 30. Methods: Thirty patients with different stage of glaucoma and 14 patients with typical glaucomatous changes of the ONH without visual field loss (preperimetric glaucoma) were included in the analysis. The control group was represented by 27 adults without ocular pathology with intraocular pressure of < 21 mmHg and normal visual fields. The sensitivity and specificity of the »Number« was determined at a cut-off level of 23 and 30. Results: The sensitivity of the »Number« at a cut-off level of 30 for the glaucoma group was 74% at a specificity of 86%, at a cut-off of 23 the sensitivity increased to 83% at a specificity of 76%. The discriminating ability of the »Number« in the group with preperimetric glaucoma was low, with the sensitivities of 36% and 50% at a cut-off value of 30 and 23, respectively.Conclusions: The parameter »Number« yielded good separation between normal eyes and eyes with moderate and advanced glaucoma. However, the sensitivity of the »Number« in eyes with mild glaucoma and especially with preperimetric glaucoma was low. Because of the great interindividual variability of the RNFL, the assessment of RNFL thickness change over time would be more appropriate to detect early glaucomatous changes.

Background. Retinal nerve fibre layer (RNFL) loss is an early sign of glaucoma and may precede the optic disc damage and visual field loss. Scanning laser polarimetry (SLP) is a quantitative method measuring the RNFL thickness surrounding the optic disc. The instrument (GDx, Laser Diagnostics Technologies, San Diego, CA) uses a near-infrared diode polarized light which by passing through the birefringent RNFL undergoes a change of polarization (i. e. retardation). The resulting phase shift (retardation) is related to the thickness of the RNFL. The method is used primarily in the diagnosis of glaucoma, but it is also helpful in assessment of the RNFL in optic neuropathy of different etiopathogenesis.Conclusions. In the article we presented the results of SLP in a healthy subject and in glaucoma patients with different stages of the disease. In the diagnosis of early and moderate glaucoma SLP has low sensitivity and specificity and cannot substitute a thorough ophthalmologic examination. Nevertheless, it provides additional information to our management of glaucoma patients.