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Simulation of DME changes on OCT
Author(s) -
CORREIA A,
ARAÚJO A,
BARBEIRO S,
CARAMELO F,
SERRANHO P,
MORGADO M,
BERNARDES R
Publication year - 2014
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2014.2443.x
Subject(s) - outer nuclear layer , homogeneous , cirrus , monte carlo method , ophthalmology , optics , nuclear medicine , retinal , physics , mathematics , medicine , statistics , statistical physics , meteorology
Purpose To identify the changes at the cellular level responsible for the differences seen in OCT scans of DME patients. Methods Cirrus HD‐OCT (Carl Zeiss Meditec, Dublin, CA, USA) scans of DME eyes (12 eyes of 8 patients: 68.9±7.5 yrs) and healthy control (HC) eyes (12 eyes of 11 controls: 63.0±3.6 yrs) were acquired from our database. The ONL was segmented by a human grader (AC) and each segmentation was aligned to its upper boundary, averaged into an A‐scan and then normalized by the intensity at the RPE to discard the effect of media opacities. To understand the significant differences found between the profiles of DME and HC, a Monte Carlo method for simulating light scattering with a model of the ONL was implemented. The inputs for the method are calculated using Mie theory by assuming that the ONL may be modelled as a homogeneous medium filled with nuclei. Changes in each model parameter (e.g. nucleus' size) were tested and compared with the measured profile to identify which cellular change could best reproduce the OCT differences found between HC and DME patients. Moreover, the DME group was divided into those without significant visible changes and those with increased ONL volume. Results The simulation method successfully reproduced the differences observed between the HC and DME groups. For the DME cases with increased volume, it was possible to match the simulated and acquired profiles by using the measured increase in ONL thickness. In the DME case with no significant changes, it was necessary to increase only the nucleus size to be able to reproduce the measured profiles. Conclusion The method proposed is capable of reproducing the reflectivity changes measured on OCT scans of the ONL of DME eyes and to justify these at the subcellular level.