Purpose:
To determine the relationship between standard automated perimetry (SAP) and the peripapillary retinal nerve fiber layer (RNFL) thickness measured with spectral-domain optical coherence tomography (OCT) in patients with glaucomatous optic neuropathy
Methods:
81 consecutive subjects with open-angle glaucoma were prospectively selected. All had to have intraocular pressure higher than 21 mmHg and glaucomatous optic nerve head morphology, regardless of SAP results. All subjects underwent a reliable SAP (Humprey Field Analyzer 750i, Zeiss Humphrey Systems, Dublin, Ca; 24-2 SITA Standard strategy) and imaging with the Cirrus HD OCT (Carl Zeiss Meditec, Dublin, Ca; Optic disc cube 200x200 scanning protocol). One eye from each subject was randomly chosen, unless only one eye met the inclusion criteria. Left eyes were converted to a right eye format. Threshold values at each point of the visual field (VF) were expressed in a linear scale. The Kolmogorov Smirnov test was applied to check that the data were normally distributed. Pearson correlations were calculated between OCT parameters, SAP indices, and VF regions of related points.
Results:
Mean age was 61.9±10.2 years. Mean deviation of SAP was -7.3±5.1 dB. Mild to moderate correlations were observed between the parameters of both devices. The strongest correlation was found between the visual field index (VFI) and the RNFL thickness at 7 clock-hour position (0.472, p<0.001). The superior VF regions and RNFL segments were most strongly correlated at the 6 and 7 o’clock positions (r ranged from 0.3 to 0.5)
Conclusions:
Determining the correspondence between VF and OCT measurements may help to clarify the relationship between structural and functional changes in open-angle glaucoma. There was moderate association between the VF regions and the RNFL thickness measured with OCT in patients with glaucomatous optic neuropathy. SAP indices and VF regions correlated moderately well with RNFL thicknesses at the vertical axis of the optic disc measured with OCT.
Keywords: imaging/image analysis: clinical • visual fields • optic disc