Background/aims: Scanning laser polarimetry (SLP) uses a confocal scanning las er ophthalmoscope with an integrated polarimeter to evaluate the thickness of th e retinal nerve fibre layer (RNFL). The aim of this study was to verify the abil ity of the SLP to detect differences in RNFL thickness between normal and glauco matous eyes and between glaucomatous eyes subdivided in groups by the severity o f visual field damage. Methods: This was a cross sectional retrospective study. The charts of 40 healthy subjects and 68 glaucoma patients who underwent complete ophthalmological examination, optic disc stereophotography, peripapillary, and macular SLP imaging were reviewed. The right eye of subjects eligible for the study was enrolled. Only eyes with SLP examinations indicating a minimised effect of anterior segment birefringence based on macular image were included. The ability of retardation parameters to discriminate between healthy and glaucomatous eyes was evaluated. Based on visual field loss, glaucoma patie nts were subdivided in three subgroups (early, moderate, and severe). RNFL thick ness between healthy control group and glaucoma subgroups was compared. RNFL thi ckness and visual field loss correlation was evaluated. Results: There was a sig nificant difference in superior and inferior maximum RNFL thickness between norm al and glaucomatous eyes (p < 0.001). With these two parameters, the area under receiver operator characteristic curve was 0.75 and 0.74, respectively. Superior and inferior RNFL thicknesswas significantly different between healthy control group and all glaucoma subgroups (p< 0.001)-and between glaucoma subgroups (p< 0.05), except for early and moderate glaucoma subgroups (p >0.05). Linear regres sion showed a weak correlation between RNFL thickness and visual field loss. Con clusion: These results suggest that once visual field loss is established, small er reductions in the RNFL thickness detected by SLP are necessary for a given re duction of mean defect value. Background / aims: Scanning laser polarimetry (SLP) uses a confocal scanning lasers ophthalmoscope with an integrated polarimeter to evaluate the thickness of th e retinal nerve fiber layer (RNFL). The aim of this study was to verify the abil ity of the SLP to detect differences in RNFL thickness between normal and glauco matous eyes and between glaucomatous eyes subdivided in groups by the severity of visual field damage. Methods: This was a cross sectional retrospective study. The charts of 40 healthy subjects and 68 glaucoma patients who underwent complete The right eye of subjects eligible for the study was enrolled. Only eyes with SLP examinations indicating a minimized effect of anterior segment birefringence based on macular image were included. The ability of retardation parameters to discriminate between healthy and glaucomatous eyes was as. Based on visual f RNFL thi ness were subdivided in three subgroups (early, moderate, and severe). RNFL thick ness between healthy control group and glaucoma subgroups was compared. nificant difference in superior and inferior maximum RNFL thickness between norm al and glaucomatous eyes (p <0.001). With these two parameters, the area under receiver operator characteristic curve was 0.75 and 0.74, respectively. Superior and inferior RNFL thickness was significantly different between healthy control group and all glaucoma subgroups (p <0.001) -and between glaucoma subgroups (p <0.05) except for early and moderate glaucoma subgroups (p> 0.05). Conline sons showed a weak correlation between RNFL thickness and visual field loss. Con clusion: These results suggest that once visual field loss is established, small er reductions in the RNFL thickness detected by SLP are necessary for a given re ductionof mean defect value.