title: Enhancement of Corneal Visibility in Optical Coherence Tomography Images Using Corneal Adaptive Compensation.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  CAC may find wide applicability in clinical practice and could contribute to improved morphometric and biomechanical understanding of the cornea.
authors.affiliation: 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.
authors.forename: Michaël J A
authors.initials: MJ
authors.lastname: Girard
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Marcus
authors.initials: M
authors.lastname: Ang
authors.affiliation: In vivo Biomechanics Laboratory Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore.
authors.forename: Cheuk Wang
authors.initials: CW
authors.lastname: Chung
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Farook
authors.affiliation: 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.
authors.forename: Nick
authors.initials: N
authors.lastname: Strouthidis
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore.
authors.forename: Jod S
authors.initials: JS
authors.lastname: Mehta
authors.affiliation: Université de la Polynésie française, Tahiti, French Polynesia.
authors.forename: Jean Martial
authors.initials: JM
authors.lastname: Mari
keywords: adaptive compensation; cornea; corneal adaptive compensation; corneal scarring; digital image processing; optical coherence tomography