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D. Cabrera DeBuc et al.
been accomplished throughout teamwork of clinicians, researchers and industry that
significantly contributed to facilitating clinical solutions into a medical device.
During the last decade, OCT technology has advanced drastically in terms of
speed, resolution and sensitivity and has become a key diagnostic tool in the areas
of retinal and optic nerve pathologies [5]. Recent advancements in OCT imaging
allow the visualization of retinal structures in a few seconds with an axial resolution
of ~2 microns. The upgrade of both scanning speed and resolution has significantly
increased the potential of OCT to visualize more detailed retinal structures, and
thus has further enhanced its capability of providing qualitative assessment of tissue
features and pathologies or objective quantitative measurements.
The qualitative assessment of the OCT image involves mostly the description
of the structural changes of the retina from the vitreo-retinal interface down to the
choroid. In this chapter, we are not aiming to describe these morphological features
as they would involve almost the entire spectrum of retinal pathologies. However, it is
important to emphasize the common language intended to be used for the description
of retinal structure that has been the source of substantial debate ever since OCT
imaging has been introduced in the clinical practice. Recently, the International
Nomenclature for Optical Coherence Tomography (IN·OCT) Panel has developed
its recommendations for the usage of common language in OCT nomenclature (see
[6].
The quantitative assessment of retinal OCT images refers mostly to the thickness
measurements on OCT images. These thickness measurements can help the clinician
in the decision-making process in various pathologies, for example, in DME. The
Diabetic Retinopathy Clinical Research Network (DRCR.net) has made substantial
work in defining the nomenclature and landmarks to be used for OCT diagnostics,
the most important of these being the central subfield mean thickness of the macula
[7–10]. However, quantitative measurements can also be made for various retinal
features, like the area of retinal atrophy and drusen volume in dry age-related macular degeneration, the thickness of the macular ganglion cell complex (GCC), retinal
nerve fiber layer (RNFL) and the opening of the Bruch’s Membrane in the optic nerve
head (ONH) in glaucoma diagnostics [11–14]. Recently, the thickness measurement
of the choroid has become possible and offers an exciting insight into retinal pathophysiology [15]. Finally, the optical and textural properties of the OCT scans can
be quantitatively described, although this latter has not yet been used in the daily
diagnostic routine [16, 17].
An exciting field in OCT diagnostics is the segmentation of the retinal layers seen
on the B-scans. Our group has been among the first in the field to describe OCT image
segmentation [18] and applied it clinically to both time- and frequency-domain OCT
imaging data. The assessment of retinal microstructure can help to better understand
the cross-talk between the various cell types and cellular layers of the retina in health
and disease and it may provide a window to the central nervous system. In glaucoma,
the macular ganglion cell complex (GCC, comprising the macular RNFL, Ganglion
cell layer (GCL) and inner plexiform layer (IPL)) seems to be a very sensitive marker
for diagnostics and monitoring of disease progression [19].
D. Cabrera DeBuc et al.
been accomplished throughout teamwork of clinicians, researchers and industry that
significantly contributed to facilitating clinical solutions into a medical device.
During the last decade, OCT technology has advanced drastically in terms of
speed, resolution and sensitivity and has become a key diagnostic tool in the areas
of retinal and optic nerve pathologies [5]. Recent advancements in OCT imaging
allow the visualization of retinal structures in a few seconds with an axial resolution
of ~2 microns. The upgrade of both scanning speed and resolution has significantly
increased the potential of OCT to visualize more detailed retinal structures, and
thus has further enhanced its capability of providing qualitative assessment of tissue
features and pathologies or objective quantitative measurements.
The qualitative assessment of the OCT image involves mostly the description
of the structural changes of the retina from the vitreo-retinal interface down to the
choroid. In this chapter, we are not aiming to describe these morphological features
as they would involve almost the entire spectrum of retinal pathologies. However, it is
important to emphasize the common language intended to be used for the description
of retinal structure that has been the source of substantial debate ever since OCT
imaging has been introduced in the clinical practice. Recently, the International
Nomenclature for Optical Coherence Tomography (IN·OCT) Panel has developed
its recommendations for the usage of common language in OCT nomenclature (see
[6].
The quantitative assessment of retinal OCT images refers mostly to the thickness
measurements on OCT images. These thickness measurements can help the clinician
in the decision-making process in various pathologies, for example, in DME. The
Diabetic Retinopathy Clinical Research Network (DRCR.net) has made substantial
work in defining the nomenclature and landmarks to be used for OCT diagnostics,
the most important of these being the central subfield mean thickness of the macula
[7–10]. However, quantitative measurements can also be made for various retinal
features, like the area of retinal atrophy and drusen volume in dry age-related macular degeneration, the thickness of the macular ganglion cell complex (GCC), retinal
nerve fiber layer (RNFL) and the opening of the Bruch’s Membrane in the optic nerve
head (ONH) in glaucoma diagnostics [11–14]. Recently, the thickness measurement
of the choroid has become possible and offers an exciting insight into retinal pathophysiology [15]. Finally, the optical and textural properties of the OCT scans can
be quantitatively described, although this latter has not yet been used in the daily
diagnostic routine [16, 17].
An exciting field in OCT diagnostics is the segmentation of the retinal layers seen
on the B-scans. Our group has been among the first in the field to describe OCT image
segmentation [18] and applied it clinically to both time- and frequency-domain OCT
imaging data. The assessment of retinal microstructure can help to better understand
the cross-talk between the various cell types and cellular layers of the retina in health
and disease and it may provide a window to the central nervous system. In glaucoma,
the macular ganglion cell complex (GCC, comprising the macular RNFL, Ganglion
cell layer (GCL) and inner plexiform layer (IPL)) seems to be a very sensitive marker
for diagnostics and monitoring of disease progression [19].