Abstract
Purpose: :
To evaluate the structure-function relationship between the threshold values obtained with frequency-doubling perimetry (FDT) and the peripapillary retinal nerve fiber layer (RNFL) thickness measured with time-domain optical coherence tomography (OCT) and with scanning laser polarimetry (GDx) with variable corneal compensation (VCC), in glaucoma patients.
Methods: :
This study was conducted in accordance with the tenets of the Declaration of Helsinki and approved by the Clinical Research Ethics Committee of Aragón (CEICA). Seventy two glaucomatous eyes of 72 subjects were prospective and consecutively selected. All of them underwent a comprehensive ophthalmic examination, at least 2 reliable standard automated perimetries SAPs, a full threshold FDT C-20-5 test (Welch Allyn/Humphrey Zeiss, Dublin, Ca) and imaging with the Stratus OCT (Carl Zeiss Meditec, Dublin, Ca) and the GDx-VCC (Laser Diagnostic Technology, San Diego, Ca). All participants had intraocular pressure higher than 21 mmHg and abnormal SAP results. Left eyes were converted to a right eye format.The 17 threshold values tested with FDT were converted to a linear scale.After checking for a normal distribution of the variables, Pearson correlations were calculated between the converted-FDT parameters and the RNFL thickness, at 12 clock-hours positions and at 4 quadrants, measured with OCT. Pearson correlations were also calculated between FDT and GDx-VCC parameters.
Results: :
All techniques presented abnormal results in most cases. Mild to moderate correlations were found between a few FDT points and the RNFL thickness measured with OCT and GDx-VCC. For OCT, the strongest correlation was observed between the point 5 of FDT and the RNFL thickness at 7 clock-hour position (0.434, p<0.001); and for GDx-VCC, the strongest correlation was found between the point 5 of FDT and the nerve fiber indicator (NFI; -0.347, p=0.005).
Conclusions: :
FDT, OCT and GDx detected changes in glaucoma patients with visual field losses in SAP. The mild agreement between FDT parameters and RNFL thickness measured with OCT and GDx-VCC suggest that these instruments evaluated glaucoma damage independently.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • optic disc