Abstract
Background: The reliability of an instrument is dependent on its accuracy and repeatability. The iVue-100 optical coherence tomographer (OCT) is a spectral domain device that has the advantage of being able to measure both the anterior and posterior segments of the eye. But its repeatability for macular thickness measurements has not been assessed and this was the primary purpose of this study.Aim: To determine the repeatability of the iVue-100 OCT for macular thickness measurements.Settings: This study was conducted at the University of KwaZulu-Natal.Methods: Repeatability (intra-observer, inter-observer and inter-session) of the iVue-100 OCT was assessed on 50 participants selected using convenience sampling. Data were statistically analysed using Bland–Altman analysis, the intra-class correlation coefficient (ICC), coefficient of variation and the paired t-test.Results: The mean age and standard deviation for the 50 participants were 23.88 ± 6.93 years (range 18–51 years). The ICCs for intra-observer repeatability ranged between 0.940 and 0.989, whereas the coefficients of variation ranged between 0.040 and 0.084. For both inter-observer and inter-session repeatability, the t-test showed no statistically significant differences (p > 0.05), and Bland–Altman analysis found the majority of the measurements to be within the 95% limits of agreement.Conclusion: Irrespective of whether repeated measurements are being taken consecutively by the same examiner, by a different observer or at a different time, the iVue-100 OCT is highly reliable in terms of repeatability which is of paramount importance in any clinical or research setting.
Highlights
The word fovea refers to a small region and in terms of the retina is the area in the posterior pole measuring approximately 1.5 mm in diameter, situated approximately 4 mm temporal to the optic disc.[1,2,3] The fovea allows the best visual resolution in the entire retina.[4,5] Unlike the rest of the retina, the macula contains more than one layer of ganglion cells and an additional pigment called xanthophyll
For the iVue-100 optical coherence tomographer (OCT) to be classified as producing valid clinical macular thickness measurements, its repeatability has to be high
The intra-class correlation coefficient (ICC), coefficient of variation (CoV) and Bland–Altman analysis have been used as indicators of instrument repeatability in previous studies involving macular thickness measurements.[12,21,22,26]
Summary
The word fovea refers to a small region and in terms of the retina is the area in the posterior pole measuring approximately 1.5 mm in diameter, situated approximately 4 mm temporal to the optic disc.[1,2,3] The fovea allows the best visual resolution in the entire retina.[4,5] Unlike the rest of the retina, the macula contains more than one layer of ganglion cells and an additional pigment called xanthophyll. The perifovea, which is rich in blood vessels, is where the ganglion cell layer is the thickest.[6] The histological differences of the different areas result in varying thickness in the sub-areas of the macula. Its repeatability for macular thickness measurements has not been assessed and this was the primary purpose of this study
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