A Digital Staining Algorithm for Optical Coherence Tomography Images of the Optic Nerve Head.
OBJECTIVE
To digitally stain spectral-domain optical coherence tomography (OCT) images of the optic nerve head (ONH), and highlight either connective or neural tissues.


METHODS
OCT volumes of the ONH were acquired from one eye of 10 healthy subjects. We processed all volumes with adaptive compensation to remove shadows and enhance deep tissue visibility. For each ONH, we identified the four most dissimilar pixel-intensity histograms, each of which was assumed to represent a tissue group. These four histograms formed a vector basis on which we 'projected' each OCT volume in order to generate four digitally stained volumes P1 to P4. Digital staining was also verified using a digital phantom, and compared with k-means clustering for three and four clusters.


RESULTS
Digital staining was able to isolate three regions of interest from the proposed phantom. For the ONH, the digitally stained images P1 highlighted mostly connective tissues, as demonstrated through an excellent contrast increase across the anterior lamina cribrosa boundary (3.6 ± 0.6 times). P2 highlighted the nerve fiber layer and the prelamina, P3 the remaining layers of the retina, and P4 the image background. Further, digital staining was able to separate ONH tissue layers that were not well separated by k-means clustering.


CONCLUSIONS
We have described an algorithm that can digitally stain connective and neural tissues in OCT images of the ONH.


CONCLUSIONS
Because connective and neural tissues are considerably altered in glaucoma, digital staining of the ONH tissues may be of interest in the clinical management of this pathology.
GePaSud, Université de la Polynésie française, Tahiti, French Polynesia.
Jean-Martial
JM
Mari
Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; Department of Ophthalmology, YLL School of Medicine, National University of Singapore, Singapore.
Tin
T
Aung
Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; Department of Ophthalmology, YLL School of Medicine, National University of Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School, Singapore.
Ching-Yu
CY
Cheng
Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK ; Discipline of Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, NSW, Australia.
Nicholas G
NG
Strouthidis
Singapore Eye Research Institute, Singapore National Eye Centre, Singapore ; Ophthalmic Engineering & Innovation Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore.
Michaël J A
MJ
Girard
adaptive compensation; digital staining; glaucoma; optic nerve head; optical coherence tomography