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CS Joergensen, JL Hougaard, B Sander, H Lund-Andersen; A New Mapping System for Optical Coherence Tomography . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2553.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To evaluate a new mapping system for optical coherence tomography (OCT) with evenly distances between scanning lines instead of the traditional mapping system. Standard OCT with 6 radial scans gives an over representation of the foveal center and a relative under representation of the more peripheral part of the retina with a minimum distance between radial scan of one disc area. Methods:6 circle scans were obtained with diameters 500, 1000, 1500, 2000, 2500 and 3000 µm from the foveola. In addition one horizontal and one vertical scan were obtained to measure foveal thickness. For comparison six radial scans were obtained using the standard software of Humphrey Zeiss. Both circle and radial scans were mapped by specialized software with equal setup for the two scanning procedures. Reproducibility was evaluated on healthy controls. Overall retinal thickness (i.e. mean of 600 values in the macular region) of the circle and radial scans was compared on healthy subjects (n=10) and diabetic patients with (n=10) and without significant edema (n=10). Results:Reproducibility of scans was better than 4 % in both circle and radial scans, assessed as the difference between the first and second scan session at a specific diameter or orientation. There was no significant difference in overall retinal thickness of the macular region between the two methods for neither healthy subjects, diabetic patients with and without edema (p = 0,59, p = 0,97 and p = 0,95 respectively). Localized edemas were better visualized due to smaller distance between scan and thereby better resolution in circle scans than in radial scans. Conclusion: Retinal thicknesses calculated from circle scans are proven to be as reproducible as assessed by radial scans and furthermore show the same overall thickness of the macular region. In addition circle scans are more sensitive in the periphery. The new software features a comparison to healthy individuals and calculates a mean value for each of the 6 scans performed making it more useful in detecting abnormal localized thickness and retinal changes.
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