Michaël J A Girard1, Marcus Ang2, Cheuk Wang Chung3, Mohamed Farook2, Nick Strouthidis4, Jod S Mehta5, Jean Martial Mari6. 1. In vivo Biomechanics Laboratory Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore ; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore. 2. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore. 3. In vivo Biomechanics Laboratory Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore. 4. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust & UCL Institute of Ophthalmology, London, UK. 5. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore. 6. Université de la Polynésie française, Tahiti, French Polynesia.
Abstract
PURPOSE: To improve the contrast of optical coherence tomography (OCT) images of the cornea (post processing). METHODS: We have recently developed standard compensation (SC) algorithms to remove light attenuation artifacts. A more recent approach, namely adaptive compensation (AC), further limited noise overamplification within deep tissue regions. AC was shown to work efficiently when all A-scan signals were fully attenuated at high depth. But in many imaging applications (e.g., OCT imaging of the cornea), such an assumption is not satisfied, which can result in strong noise overamplification. A corneal adaptive compensation (CAC) algorithm was therefore developed to overcome such limitation. CAC benefited from local A-scan processing (rather than global as in AC) and its performance was compared with that of SC and AC using Fourier-domain OCT images of four human corneas. RESULTS: CAC provided considerably superior image contrast improvement than SC or AC did, with excellent visibility of the corneal stroma, low noise overamplification, homogeneous signal amplification, and high contrast. Specifically, CAC provided mean interlayer contrasts (a measure of high stromal visibility and low noise) greater than 0.97, while SC and AC provided lower values ranging from 0.38 to 1.00. CONCLUSION: CAC provided considerable improvement compared with SC and AC by eliminating noise overamplification, while maintaining all benefits of compensation, thus making the corneal endothelium and corneal thickness easily identifiable. TRANSLATIONAL RELEVANCE: CAC may find wide applicability in clinical practice and could contribute to improved morphometric and biomechanical understanding of the cornea.
PURPOSE: To improve the contrast of optical coherence tomography (OCT) images of the cornea (post processing). METHODS: We have recently developed standard compensation (SC) algorithms to remove light attenuation artifacts. A more recent approach, namely adaptive compensation (AC), further limited noise overamplification within deep tissue regions. AC was shown to work efficiently when all A-scan signals were fully attenuated at high depth. But in many imaging applications (e.g., OCT imaging of the cornea), such an assumption is not satisfied, which can result in strong noise overamplification. A corneal adaptive compensation (CAC) algorithm was therefore developed to overcome such limitation. CAC benefited from local A-scan processing (rather than global as in AC) and its performance was compared with that of SC and AC using Fourier-domain OCT images of four human corneas. RESULTS: CAC provided considerably superior image contrast improvement than SC or AC did, with excellent visibility of the corneal stroma, low noise overamplification, homogeneous signal amplification, and high contrast. Specifically, CAC provided mean interlayer contrasts (a measure of high stromal visibility and low noise) greater than 0.97, while SC and AC provided lower values ranging from 0.38 to 1.00. CONCLUSION: CAC provided considerable improvement compared with SC and AC by eliminating noise overamplification, while maintaining all benefits of compensation, thus making the corneal endothelium and corneal thickness easily identifiable. TRANSLATIONAL RELEVANCE: CAC may find wide applicability in clinical practice and could contribute to improved morphometric and biomechanical understanding of the cornea.
Authors: Michaël J A Girard; Nicholas G Strouthidis; C Ross Ethier; Jean Martial Mari Journal: Invest Ophthalmol Vis Sci Date: 2011-09-29 Impact factor: 4.799
Authors: Jean Martial Mari; Nicholas G Strouthidis; Sung Chul Park; Michaël J A Girard Journal: Invest Ophthalmol Vis Sci Date: 2013-03-01 Impact factor: 4.799
Authors: Nicolas Foin; Jean Martial Mari; Sukhjinder Nijjer; Sayan Sen; Ricardo Petraco; Matteo Ghione; Carlo Di Mario; Justin E Davies; Michaël J A Girard Journal: Cardiovasc Revasc Med Date: 2013-04-28
Authors: John Johnstone; Massimo Fazio; Kulawan Rojananuangnit; Brandon Smith; Mark Clark; Crawford Downs; Cynthia Owsley; Michael J A Girard; Jean Martial Mari; Christopher A Girkin Journal: Invest Ophthalmol Vis Sci Date: 2014-03-28 Impact factor: 4.799
Authors: Tae-Woo Kim; Larry Kagemann; Michaël J A Girard; Nicholas G Strouthidis; Kyung Rim Sung; Christopher K Leung; Joel S Schuman; Gadi Wollstein Journal: Curr Eye Res Date: 2013-09 Impact factor: 2.424
Authors: Preeti Gupta; Elizabeth Sidhartha; Michael J A Girard; Jean Martial Mari; Tien-Yin Wong; Ching-Yu Cheng Journal: PLoS One Date: 2014-05-05 Impact factor: 3.240
Authors: Marcus Ang; Wesley Chong; Huiqi Huang; Wan Ting Tay; Tien Yin Wong; Ming-Guang He; Tin Aung; Jodhbir S Mehta Journal: PLoS One Date: 2013-06-04 Impact factor: 3.240
Authors: Yijun Cai; Jorge L Alio Del Barrio; Mark R Wilkins; Marcus Ang Journal: Graefes Arch Clin Exp Ophthalmol Date: 2016-10-08 Impact factor: 3.117
Authors: Marcus Ang; Anna C S Tan; Chui Ming Gemmy Cheung; Pearse A Keane; Rosa Dolz-Marco; Chelvin C A Sng; Leopold Schmetterer Journal: Graefes Arch Clin Exp Ophthalmol Date: 2018-01-09 Impact factor: 3.117
Authors: Cheuk Wang Chung; Marcus Ang; Mohamed Farook; Nicholas G Strouthidis; Joddhbir S Mehta; Jean Martial Mari; Michaël J A Girard Journal: Transl Vis Sci Technol Date: 2016-09-08 Impact factor: 3.283
Authors: Jean-Martial Mari; Tin Aung; Ching-Yu Cheng; Nicholas G Strouthidis; Michaël J A Girard Journal: Transl Vis Sci Technol Date: 2017-02-02 Impact factor: 3.283
Authors: Marcus Ang; Kavya Devarajan; Suchandrima Das; Gary H F Yam; Hla Mynt Htoon; Si Chen; Xinyu Liu; Linbo Liu; Michael Girard; Jodhbir S Mehta Journal: Sci Rep Date: 2018-07-31 Impact factor: 4.379