Abstract
Purpose: :
To measure peripapillary total and residual retinal thickness (= total retinal thickness - RNFL thickness) and RNFL thickness in normal subjects and glaucoma patients and to compare diagnostic value of RNFL and total retinal thickness to discriminate between normal subjects and glaucoma patients.
Methods: :
Circular B-Scans (diameter 3.4 mm, 768 AScans) around the optic nerve head (ONH) were acquired in 157 healthy subjects (N), 45 preperimetric (PG) and 89 perimetric glaucoma (G) patients using spectral domain OCT (Spectralis HRA & OCT, Heidelberg Engineering). The 768 segmentation values of the three borders: inner limiting membrane, posterior retinal nerve fiber boundary and pigment epithelium provided by the Spectralis software were used to calculate thickness values. Thickness values were averaged to 64 sectors (5.6 deg each, fig. 1) with 0 deg coresponding to 9 o'clock.
Results: :
Mean total retinal thickness (mean±SD) was (317±16) µm, (299±20) µm and (289±22) µm in N, PG and G, mean residual retinal thickness was (221±11) µm, (219±14) µm and (221±14) µm in N, PG and G, and mean RNFL thickness was (97±10) µm, (80±12) µm and (61±14) µm in N, PG and G. There is a significant reduction (p<0.001) of mean total retinal thickness and mean RNFL thickness compared to normal subjects for both glaucoma groups. Mean residual retinal thickness of both glaucoma groups is not significantly changed compared to normal subjects. The area under the ROC curves for mean RNFL thickness, mean total retinal thickness and mean residual retinal thickness for the discrimination of perimetric glaucoma patients (G) to normal subjects (N) is 0.979, 0.901 and 0.502 (fig. 2).
Conclusions: :
RNFL thickness allows better discrimination of perimetric glaucoma patients from normal subjects than total retinal thickness.
Clinical Trial: :
www.clinicaltrials.gov NCT00494923
Keywords: nerve fiber layer • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina