Comparison of Spectral Domain Optical Coherence Tomography in the Measurement of Peripapillary Retinal Nerve Fiber Layer Thickness

Abstract

Purpose: : To determine the relationship between peripapillary retinal nerve fiber layer (RNFL) thickness measured by 2 different spectral domain optical coherence tomography (OCT) systems.

Methods: : Forty-nine eyes of 49 glaucoma patients were imaged using Cirrus HD OCT (Carl Zeiss Meditec, Dublin, Ca) and Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) at the same visit. Participants had intraocular pressure higher than 21 mmHg and abnormal standard automated perimetry. Student paired t test, Pearson’s correlation coefficient, and Bland-Altman analysis of RNFL thickness measurements were calculated between the equivalent parameters of both devices.

Results: : Mean age was 64.5±7.1 years and mean deviation of standard automated perimetry was -5.0±5.7 dB. For average thickness there was a highly significant linear relationship between the values obtained from both instruments (r=0.899, p<0.001). The strongest correlations were observed between the inferior (0.935, p>0.001) and superior (0.922, p<0.001) quadrant thicknesses. RNFL thickness at nasal and temporal quadrants were significant different by paired t testing (p=0.002 and p<0.001, respectively). The Bland-Altman plot did not reveal a significant difference between measurements of Cirrus and Spectralis OCT.

Conclusions: : There were significant differences in RNFL measurements at horizontal axis (nasal and temporal quadrants) as determined by Cirrus OCT and Spectralis OCT, despite an excellent correlation of all RNFL thickness measurements.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • optic disc