Abstract
Purpose: :
To evaluate and compare the regional relationships between visual field sensitivity and retinal nerve fiber layer (RNFL) thickness as measured by Spectral-Domain Optical Coherence Tomography (SD-OCT), Variable Corneal Compensation scanning laser polarimetry (GDx-VCC) and Enhanced Corneal Compensation Scanning Laser Polarimetry (GDx-ECC).
Methods: :
One hundred and fifty eyes of 150 patients (50 with healthy eyes, 50 with suspected glaucoma and 50 with glaucoma) were tested, in a prospective cross-sectional study, on Cirrus SD-OCT, GDx-VCC, GDx-ECC and standard automated perimetry. Raw data on RNFL thickness were extracted for 256 peripapillary sectors of 1.40625° each for the OCT measurement ellipse and 64 peripapillary sectors of 5.625° each for the GDx-VCC and GDx-ECC measurement ellipse. Correlations between peripapillary RNFL thickness in six sectors and visual field sensitivity in the six corresponding areas were evaluated using linear and logarithmic regression analysis. Receiver operating curve areas were calculated for each instrument.
Results: :
With spectral-domain OCT, the correlations (r²) between RNFL thickness and visual field sensitivity ranged from 0.123 (nasal RNFL and corresponding visual field area, linear regression) to 0.876 (supratemporal RNFL and corresponding visual field area, logarithmic regression). By comparison, with GDx-ECC, the correlations ranged from 0.122 (temporal RNFL and corresponding visual field area, linear regression) to 0.642 (inferotemporal RNFL and corresponding visual field area, logarithmic regression), and with GDx-VCC, the correlations ranged from 0.084 (temporal RNFL and corresponding visual field area, linear regression) to 0.403 (supratemporal RNFL and corresponding visual field area, logarithmic regression). In pair-wise comparisons, these structure-function correlations were generally stronger with SD-OCT than with GDx VCC and with logarithmic regression than with linear regression. The largest areas under the receiver operating curve were seen for GDx-ECC Nerve Fiber Indicator (NFI) (0.981 ± 0.096; p < 0.001) in eyes with glaucoma and for GDx-ECC NFI (0.924 ± 0.102; p < 0.001) in eyes with suspected glaucoma.
Conclusions: :
The structure-function relationship was significantly stronger with SD-OCT than with GDx-ECC and than with GDx-VCC, and was better expressed logarithmically than linearly. The GDx-ECC seems to have the best ability to discriminate glaucomatous or suspected glaucomatous eyes from normal eyes.
Keywords: imaging/image analysis: clinical • nerve fiber layer • visual fields