Retinal nerve fiber layer examined by GDxVCC in early diagnosis of glaucoma

Objective To evaluate the usefulness of the scanning laser polarimeter with variable corneal compensation (GDxVCC) for glaucoma detection in a Chinese population,and to investigate the retinal nerve fiber layer (RNFL) thickness difference between normal subjects and glaucoma patients.Methods Thirty-six eyes of 36 normal subjects,33 eyes of 33 primary chronic angle-closure glaucoma patients,27 eyes of 27 primary acute angle-closure glaucoma and 35 eyes of 35 primary open-angle glaucoma patients were studied.The glaucoma patients were age-matched with the normal.The thickness of retinal nerve fiber layer was measured with GDxVCC.An eye was diagnosed as glaucoma,ifone of the parameters showed P＜0.05 on the results of the examination reports including four TSNIT parameters (the average of TSNIT,superior,inferior,and TSNIT Std.Dev.),nerve fiber indicator (NFI) ＞ 30,and at least 10 consecutive defects of superpels showed in deviation map (P ＜0.05).Results Of 22 normal eyes (61.1%) were diagnosed as non-glaucoma and 82 glaucomatous eyes (86.3%) were diagnosed as glaucoma by GDxVCC.Sensitivity of the average of TSNIT,superior,inferior,TSNIT Std.Dev.,NFI and the deviation map were 48.4%,56.8%,48.4%,50.5%,62.1% respectively and specificity were 97.2%,100%,97.2%,94.4%,97.2% and 61.1% respectively.Sensitivity of detection early,moderate and progression glaucoma by GDxVCC were 77.36%,95.83%,100% respectively.Conclusions GDxVCC is a valuable technology to detect retinal nerve fiber layer defect in early glaucoma.It is shown that the NFI has highest sensitivity. Key words: Glaucoma; RNFL; GDxVCC