Relationship between time‐ and spectral‐domain optical coherence tomography in glaucoma

Abstract

Purpose To evaluate the relationship of retinal nerve fiber layer (RNFL) thicknesses obtained with two different optical coherence tomography (OCT) systems, time‐domain OCT (Stratus; Carl Zeiss Meditec, Dublin, Ca) and spectral‐domain OCT (Cirrus; Carl Zeiss Meditec), in healthy and glaucomatous eyes. Methods Seventy healthy and 71 glaucoma individuals were prospective and consecutively selected. Only one eye per subject was included in the study. Glaucoma patients had intraocular pressure higher than 21 mmHg and abnormal standard automated perimetry (SAP). All participants underwent a comprehensive ophthalmic examination and at least 2 reliable SAPs. Peripapillary RNFL measurements were acquired with 2 different OCT systems (Stratus and Cirrus OCTs). Kolmogorov‐Smirnov test was applied to check normality of variables. Then, Pearson´s correlations were calculated between parameters of both OCTs in the healthy and glaucoma groups. Results Mean age was 56.1 ± 12.1 and 62.2 ± 9.1 years in the healthy and glaucoma groups, respectively (p=0.07). Moderate to strong correlations were observed between equivalent parameters of both devices. The strongest correlations were found for average RNFL thickness (r=0.928; p<0.001) and RNFL thickness at inferior quadrant (r=0.925; P<0.001) in the glaucoma group. The RNFL thickness at 3 o’clock position showed the mildest correlation (r=0.435; p<0.001) in the healthy group. Conclusion Although RNFL parameters cannot be interchanged between both devices, the RNFL measurements of time‐ and spectral‐domain OCTs had strong correlations in glaucoma patients.