Abstract
Purpose: :
To prevent the development of visual field defects in glaucoma it is necessary to develop methods for the quantification of early structural damage. Aim of this study was to investigate the retinal nerve fibre layer thickness (RNFL) with a spectral domain OCT (SD OCT) in patients with ocular hypertension (OHT), early and advanced glaucoma in comparison to healthy controls.
Methods: :
48 healthy controls, 12 patients with OHT (normal visual field, healthy optic disc appearance, IOP > 20 mmHg), 13 preperimetric open angle glaucoma patients (normal visual field, glaucomatous disc atrophy, IOP > 20 mmHg) and 23 patients with perimetric open angle glaucoma (glaucomatous visual field loss and disc atrophy, IOP > 20 mmHg) were investigated with Spectralis HRA-OCT (Heidelberg Engineering, Germany) for valuation of retinal nerve fibre layer thickness (RNFL) with central circle scans. Both eyes of each patient was selected for statistic analysis and mean global values as well as sector data were compared using Mann-Whitney-U test.
Results: :
Normals eyes showed mean RNFL thickness of 89.75±9.26 µm with the highest values in the inferior sector (110.95±13.38 µm). Patients with perimetric glaucoma demonstrated a significant reduction of overall RNFL thickness (54.87 ±19.09µm; p=0.0001) as well as in all investigated sectors (p<0.04). In contrast in preperimetric patients RNFL loss occurred predominantly in the temporal superior sector (93.18±18.62µm), temporal horizontal (56.76±6.39µm) and temporal inferior (86.25±15.8µm)(p0.05).
Conclusions: :
Routine SD-OCT allows fast and no invasive high resolution assessment of the retinal nerve fibre layer. Significant reduction (18-23 %) of RNFL was detected in early glaucoma prior to visual field loss. Retinal nerve fibre loss was more pronounced in the temporal inferior (TI), followed by the temporal superior and even temporal horizontal sector for early glaucoma stages.
Keywords: nerve fiber layer • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • visual fields