Scanning laser polarimetry in glaucomatous and nonglaucomatous Brazilian subjects

ABSTRACT

Purpose: To compare the results of scanning laser polarimetry of the retinal nerve fiber layer obtained by using the GDx Scanning Laser System" in primary open angle glaucoma (POAG) and nonglaucomatous Brazilian subjects over 40 years, also analyzing the differences between the data obtained from right and left eyes. Methods: Forty-six POAG patients and 44 normal subjects were enrolled in this study. Retardation data were assessed by the GDx Scanning Laser System®. The medians of the parameters printed in the result were compared in these two groups, separately in the right and left eyes, using Mann-Whitney's test. Also the frequencies of outside normal parameters and quadrants of deviation from normal graph were compared in these two groups, using chi-square or Fisher's exact test. Results: All parameters obtained by GDx differed in a statistically significant way between the two groups, except symmetry for left eyes. The frequency of inferior quadrant with p<5 percent regarding deviation from normal graph was higher in the glaucomatous group. The most frequent outside normal limits parameters in the glaucomatous group were; maximal modulation, ellipse modulation, superior average and inferior average. All parameters except symmetry and superior/nasal differed between right and left eyes in the nonglaucomatous group. Conclusion: The parameters obtained by GDx are different in normal and glaucomatous subjects of that population. There are some parameters that deviate from normal values with a greater frequency in glaucomatous patients. An evident difference between the data of right and left eyes of normal subjects in this group was also observed.