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D.N. Soerensen, J. Thomadsen, B. Sander; A New Standardized OCT3 Map With Improved Resolution . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2574.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: to evaluate the measurement of the retinal thickness with an improved method compared to standard OCT3 maps. Background: a standard OCT map based on 6 radial lines has a low resolution in the periphery due to the 30 degree distance between the lines. The low sensitivity can lead to missing of a peripheral edematous area. To improve the resolution we have developed a method based on 12 radial lines with a 15 degree distance between the lines. Methods: The 12–radial lines maps were constructed off line and in respect to the standard ETDRS 9–field system. The retinal thickness of the 9 ETDRS fields was compared to the standard OCT fast macular thickness map out prints. 10 normal subjects and 10 eyes in diabetic patients with various degrees of macular oedema were included. Results: In both groups the mean difference in absolute retinal thickness was below 2 µm (healthy subjects: 0.9 µm (SD 3.3, p=0.9); diabetic patients 1.6 µm (SD 5.7, p=0.7). The range of differences for all fields in healthy eyes varied from –8 to 8 µm and in diabetic eyes from –14 to 26 µm. The outline of edematous retinal regions in the diabetic patients was grossly comparable between the standard OCT maps versus the 12–radial lines maps. However the 12–lines maps clearly showed a more detailed demarcation of the edematous regions and in several cases large edematous areas on the standard maps were separated into smaller, distinct areas when the 12–radial lines method was applied. Conclusions: The mean retinal thickness of the 9 ETDRS fields of the 12–radial lines map was quantitatively equal to the standard OCT3 map. However, in diabetic patients the difference was doubled compared to healthy controls and in 6.7 % of the total fields the difference was larger than 10 um. Qualitatively the 12–line map illustrated the edematous areas in larger details both according to the location and the extension of the oedema. In some cases a large area on the standard map differentiated to two separate edematous areas on the new map. This improvement of resolution is particularly important in clinical studies of macular edema and the monitoring of macular diseases. The improved procedure also allows the evaluation of time related fluid movements as expected in patients progressing from a more peripheral edema towards a central, significant edema.
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