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R.C. Bernardes, R.F. Monteiro, C. Lobo, J. Cunha-Vaz; OCT Increased Resolution Retinal Thickness Mapping . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4852.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To improve the retinal thickness maps based on the Optical Coherence Tomography (OCT). The original thickness maps produced by the OCT present, as a major drawback, a lack of lateral resolution because they are made based on 6 radial lines that are expected to go through the fovea. The newly generated maps overcome these problems, allowing any number of either line or radial line scans to be mixed in the same map. Methods:Data is exported from the OCT software that includes the fundus image with the projected line scan put over the image and the measure of the retinal thickness produced by the data export software. The registration of the fundus images compensates for the different positioning of the eye between exams, thus correcting for inter-exams eye movements. This registration is user-assisted. The location, orientation, start and end of line scan are automatically extracted from the fundus image. An interpolation is performed that uses the one hundred measurements for each line scan, after low-pass filtering of the original data. Scan intersection positioning is adjusted based on the percentage of the difference between measures of the different scans at the projected intersections. The allowed shifts in the positioning are restricted to a radius of 10 pixels in a best-fit mode. Results:The new retinal thickness maps generated, present an increased lateral resolution compared to the original maps. Moreover, this new system allows for the integration of any number of line scans with any positioning in the eye fundus. The user is thus allowed to increase the lateral resolution of the retinal thickness map by adding any number of scans as necessary. This will permit the computation of cyst volumes, for example, and the monitoring of the evolution of the cystoid macular edema based on a new parameter. This system also allows for detailed retinal thickness mapping after cataract surgery, lens opacification or any other reason that indicate the OCT for retinal thickness mapping. Conclusions:This new retinal thickness mapping, based on the OCT, compares favourably with the OCT original mapping. It presents increased lateral resolution, consequently allowing for the detailed mapping where the OCT has indications for use, e.g., after cataract surgery or lens opacification.
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