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D. Pau, M.E. J. van Velthoven, P.M. Garcia, R.B. Rosen; Retinal Nerve Fiber Layer Thickness Measurements: Coronal OCT/SLO versus StratusOCT . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4034.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the retinal nerve fiber layer (RNFL) thickness measurements in normal healthy subjects taken with the coronal OCT/SLO to the RNFL measurements from the conventional StratusOCT.
Ten (20 eyes) normal healthy subjects (mean age: 30 yrs) were scanned with both the conventional StratusOCT and the coronal scanning OCT/SLO system, combining OCT with confocal ophthalmoscopy. Tests were done on the same day and without pupil dilation. For the StratusOCT the fast and regular RNFL protocol was used with a 3.4 diameter circular scan. For the OCT/SLO, the newly developed RNFL scan program was used in which 3 circular scans with a diameter of 3.4 mm are captured and averaged before the algorithm outlines and measures the RNFL. The measurements are divided in four quadrants (temporal, superior, nasal and inferior = TSNI) similar to the StratusOCT. To evaluate any difference between the two OCT measurements coefficients of variation (COV) were obtained for all data.
The mean overall RNFL thickness in normal subjects was 103 ± 11 micron in the StratusOCT and 101 ± 7 micron in the OCT/SLO. For the separate quadrants (TSNI), the mean RNFL thickness was 73,125, 81 and 134 micron respectively in the StratusOCT and 81, 117, 79 and 126 micron respectively in the OCT/SLO. The mean centered COV for mean RNFL thickness was 8%, for the quadrants it was 32, 13, 36 and 9% respectively. The superior and inferior measurement showed good correlation, while the temporal and nasal measurements showed more variation.
The new RNFL scanning protocol in the OCT/SLO provides comparable RNFL thickness measurements to the StratusOCT, especially in the most important superior and inferior quadrants. The differences in temporal and nasal measurements between the two devices might be explained by slightly higher variation in the OCT/SLO measurements compared to the StratusOCT. Refinement of the algorithm in the OCT/SLO and comparison of the two techniques in patients with glaucoma is currently being done.
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