Measurement of Retinal Nerve Fiber Layer Thickness in Different Stages of Open-Angle Glaucoma Using Scanning Laser Polarimetry

【Objective】 To assess the clinical application of scanning laser polarimetry in the diagnosis of open-angle glaucoma. 【Methods】 Two hundred and fifty-two eyes from 159 normal subjects and 175 eyes from 107 patients with different stages of open-angle glaucoma were enrolled in the present study. Scanning laser polarimetry (GDxVCC) was used to obtain the retinal nerve fiber layer (RNFL) thickness. The parameters of RNFL measurement included superior RNFL thickness, inferior RNFL thickness, mean RNFL thickness, temporal-superior-nasal-inferior-temporal (TSNIT) standard deviation, symmetric value of right and left eyes and the nerve fiber index (NFI). Paired-t test was used to compare the RNFL thicknesses between the normal subjects and the glaucomatous patients, and the normal subjects and the patients with early stage glaucoma. One-way ANOVA analysis was used to compare the RNFL thicknesses among the early, advanced, and late stage glaucoma. Area under ROC curves was used to analyze the diagnostic value of GDxVCC on glaucoma. 【Results】 The mean RNFL thickness of normal subjects measured by GDxVCC was (58 ± 5)μm, which was much thicker than that of glaucomatous patients [(48 ± 11)μm, P 0.001]. The mean, superior, and inferior RNFL thickness of the patients with early stage glaucoma were statistically thinner than those of normal subjects (P = 0.000). However, the symmetric value of right and left eyes in the patients with early stage glaucoma showed no difference with that of normal subjects (P = 0.058). With the progression of glaucoma, the mean, superior and inferior RNFL thicknesses became thinner and thinner, the TSNIT standard deviation and the symmetric value of right and left eyes decreased, and the nerve fiber index increased significantly (P 0.005). And the area under ROC curves of RNFL measured by GDxVCC were 0.743 - 0.992. 【Conclusion】 The RNFL thickness could be measured by GDxVCC qualitatively and quantitatively, which could discriminate the patients with open-angle glaucoma from normal subjects. The early diagnosis of glaucoma with GDxVCC is reliable.