Abstract
Purpose: :
To investigate the relationship between retinal nerve fibre layer (RNFL) measurements in corresponding areas obtained with scanning laser polarimetry and optical coherence tomography and to compare their discriminating ability in the diagnosis of glaucoma.
Methods: :
386 subjects - 57 healthy controls, 145 ocular hypertensive patients, 89 with pre-perimetric glaucoma and 95 with perimetric glaucoma - were included in this cross-sectional study. Mean RNFL values and sector data were calculated and compared for measurements obtained by GDx VCC® and StratusOCT® (Carl Zeiss Meditec, Inc., Dublin, CA). Receiver operating characteristic (ROC) curves were constructed and sensitivity was estimated ≥ 80% of specificity to compare the discriminating ability of each imaging modality. Correlation analysis was performed between GDx VCC® and StratusOCT® in each of the 16 sectors and in each diagnostic group.
Results: :
Peripapillary RNFL thickness was 57.79 ± 6.21; 57.94 ± 6.44; 52.62 ± 7.61 and 46.05 ± 8.69 µm for TSNIT average using the GDx VCC® in the normal group, ocular hypertension group, pre-perimetric glaucoma group and perimetric glaucoma group.Peripapillary RNFL thickness in the same area using StratusOCT® was 119.16 ± 10.51; 112.93 ± 14.68; 95.79 ± 15.65 and 79.26 ± 18.93 µm in the normal group, ocular hypertension group, pre-perimetric glaucoma group and perimetric glaucoma group.For discrimination between glaucomatous and healthy eyes in GDx VCC® the NFI (Nerve Fiber Index) demonstrated the largest area under the ROC curve (AUROC) (0.962 ± 0.013) and highest sensitivity at fixed specificity of 80% (92.9%), whereas in StratusOCT® the largest AUROC (0.986 ± 0.006) and the sensitivity at fixed specificity of 80% (97.9%) was found in the inferior quadrant. For pre-perimetric glaucoma detection the NFI achieved the largest AUROC (0.783 ± 0.037) and the highest sensitivity (61.2%). In contrast the total RNFL average obtained using StratusOCT showed the largest AUROC (0.904 ± 0.025) and the highest sensitivity (83.1%). Correlation analysis of GDx VCC® and StratusOCT® measurements was performed by using Pearson's correlation coefficient. It revealed highest correlation in the inferior sector (r=0.699) and significant correlations for all investigated sectors (p<0.001).
Conclusions: :
Both the GDx VCC® and StratusOCT® demonstrate increasing RNFL loss with advanced glaucomatous damage and were comparable in the diagnosis of perimetric glaucoma. Early glaucomatous damage may be better assessed by StratusOCT®.
Clinical Trial: :
www.clinicaltrials.gov NCT00494923
Keywords: nerve fiber layer • imaging/image analysis: clinical