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P. Baptista, T. Santos, R.C. Bernardes, J. Cunha–Vaz; Increased OCT Mapping Resolution by Merging Line and Circle Scan–Types . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5728.
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© ARVO (1962-2015); The Authors (2016-present)
To increase retinal thickness mapping resolution of the Optical Coherence Tomograph (OCT – Humphrey–Zeiss, USA).
A retinal thickness Atlas (RT–Atlas) of the human macula was established based on a series of 33 retinal thickness maps from the RTA II (Retinal Thickness Analyzer, Talia, Israel), from 20 healthy volunteers, aged from 40 to 64 year–old (mean±SD: 52.4±5.9). A Principal Component Analysis (PCA) was performed to extract the major retinal thickness characteristics to build the RT–Atlas. Two scan–types were performed using the Stratus OCT: a radial scan set and a circular scan set. The radial scan set (six–radial scans – fast scan mode) are initially registered to the RT–Atlas by an iterative optimization procedure to compute the global position and orientation for the entire set, followed by individually finding the best fit of each line–scan in the neighborhood of the computed global parameters. A new retinal thickness map is then built based on the OCT data that is now registered to the RT–Atlas, thus having an origin centered on the fovea and the horizontal axis pointing to the center of the optic disc. The set of circular scans (fast scan mode) is now registered to this new map following a similar procedure, i.e., global and individual fits to the registered OCT map.
The developed procedure allows for the registration of different sets of OCT scan–types and therefore the merging of information at different locations, thus increasing the retinal thickness mapping resolution of the OCT. This method was applied to several exams, including eyes from healthy volunteers, eyes from Williams Syndrome patients and age–related macular degeneration patient eyes. A clear and useful increase in resolution of the retinal thickness map is achieved, specially in the outer bounds of the foveal area.
This new system allows for the correct establishment of retinal maps based on OCT scans, with increased resolution compared to the original map and simultaneously correcting for location and rotation. The system may be used in eyes with normal or close to normal foveal depression and proved to be useful in different pathologies and/or in their initial stages, where the correct mapping for detection of initial changes play a major role.
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