Reproducibility of High Resolution Optical Coherence Tomography Measurements of the Nerve Fiber Layer with the new Heidelberg Spectralis OCT
Résumé
Purpose Conventional time-domain OCT technology for detection of retinal nerve fiber layer (RNFL) neurodegeneration suffers from technical inaccuracy due to a lack of exact scan centering around the optic disc as well as a true follow-up possibility. In this study, we evaluated a novel high-resolution Spectral-domain OCT device (SD-OCT) with an incorporated eye-tracking feature in its ability to objectively measure the RNFL thickness (RNFLT) by testing intra-observer reproducibility in a series of healthy volunteers. Methods Triplicate circumferential RNFL scans of six peripapillary sectors were obtained from both eyes of all 31 participants. We compared the measurements of RNFLT during three separate examination days under miotic (Mi) and mydriatic (My) pupil conditions using high-speed (HS) and high-resolution (HR) scan acquisition mode. To examine the intersession reproducibility of the SD-OCT measurements the mean, standard deviation and the coefficient of variation (COV) were calculated Results No significant differences were found in all groups, independent of the mode of image acquisition and examination day (p always > 0,05). Under all conditions, low coefficients of variation (COV) between 0.545% and 3.97% (intrasession COV on baseline) were found. The intersession COV with activated follow-up mode ranged between 0.29% and 1.07%. In both settings the temporal sector showed the highest COV values. Conclusions True follow-up measurement of identical peripapillary regions may enable clinicians to detect discrete levels of retinal thickness change over time. This constitutes a crucial prerequisite for a reliable monitoring of subtle RNFL changes in neurodegenerative disorders.
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