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M. Pellegrini, A. Invernizzi, M. Cigada, G. Staurenghi; Eye Tracker and SD-OCT Repeatability: A Comparison Among Different Technologies. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2287.
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To evaluate the repeatability of macular thickness measurements of three different Spectral-Domain OCTs (SD-OCT) with different eye tracker system (ETS).
22 healthy (group 1) and 22 pathological (group 2) eyes of 44 consecutive patients were analysed using three SD-OCTs, each one equipped with different eye tracker technologies: a pre-aquisition ETS (RS-3000, Nidek, Japan), a live continuous one (Spectralis HRA+OCT, Heidelberg Engineering, Germany) and a post-processing scan aligning tool (Cirrus, Carl Zeiss Meditec, CA). For Cirrus OCT we also analyzed the "fovea finding" protocol which is able independently from ETS to auto detect the fovea and center the map on this point. In order to evaluate measurements repeatability macular volume scannings were performed two times in two different sessions on the same day for each device. The analysis was executed on the retinal thickness of five macular map central sectors. The differences between the two measures in relation to device, scan analysis protocol and group were compared with ANOVA using the average as a covariate.
Measures acquired using live continuous ETS resulted to be the most repeatable ones in both groups, followed by the post-processing one. Moreover continuous ETS was successful in the alignment process in all the patients of both group 1 and 2; on the contrary pre-acquisition ETS failed in 30% of group 1 and in 54.5% of group 2 with less repeatability. The post-processing ETS failed the alignment in 7.5% and 9.1% respectively. The differences between the 2 measures resulted strongly influenced by all the considered factors (all p values < 0.001) with slight variances among the five sectors. Except for the central sector, a significant interaction resulted between mean thickness values and devices, suggesting that some instruments are negatively influenced by retinal thickness. All the systems showed more repeatable measures in healthy eyes.
Live continuous ETS seems to be the most reliable strategy, ensuring a perfect alignment line by line of the follow up scans to the baseline.
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