The evaluation of the optical coherence tomography (OCT) is based on the identification of differences in the relative reflectivity of different tissue layers and morphological changes in tissue structures. So the examination is able to localize and grossly demarcate inflammation in the vitreous cavity (by its dynamic analysis) or beneath retinal layers as well as detail retinal changes on the chronic phases of retinal disease like fibrosis, atrophy, or retinal edema.

Optical Coherence Tomography

Objective: To demonstrate optical coherence tomography for high-resolution, noninvasive imaging of the human retina. Optical coherence tomography is a new imaging technique analogous to ultrasound B scan that can provide cross-sectional images of the retina with micrometer-scale resolution. Design: Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. Settings Research laboratory. Participants: Convenience sample of normal human subjects. Main Outcome Measures: Correlation of optical coherence retinal tomographs with known normal retinal anatomy. Results: Optical coherence tomographs can discriminate the cross-sectional morphologic features of the fovea and optic disc, the layered structure of the retina, and normal anatomic variations in retinal and retinal nerve fiber layer thicknesses with 10- μm depth resolution. Conclusion: Optical coherence tomography is a potentially useful technique for high depth resolution, cross-sectional examination of the fundus.

Optical Coherence Tomography of the Human Retina

We present what is to our knowledge the first in vivo tomograms of human retina obtained by Fourier domain optical coherence tomography. We would like to show that this technique might be as powerful as other optical coherence tomography techniques in the ophthalmologic imaging field. The method, experimental setup, data processing, and images are discussed.

https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics/volume-7/issue-03/0000/In-vivo-human-retinal-imaging-by-Fourier-domain-optical-coherence/10.1117/1.1482379.pdf

In vivo human retinal imaging by Fourier domain optical coherence tomography.

Optical coherence tomography (OCT) is an emerging biomedical optical imaging technique that performs high-resolution, cross-sectional tomographic imaging of microstructure in biological systems. OCT can achieve image resolutions of 1-15 microm, one to two orders of magnitude finer than standard ultrasound. The image penetration depth of OCT is determined by the optical scattering and is up to 2-3 mm in tissue. OCT functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale. It is a promising imaging technology because it can provide images of tissue in situ and in real time, without the need for excision and processing of specimens.

Optical coherence tomography for ultrahigh resolution in vivo imaging

Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy

Objective: To evaluate optical coherence tomography, a new technique for high-resolution cross-sectional imaging of the retina, for quantitative assessment of retinal thickness in patients with macular edema. Design: Survey examination with optical coherence tomography of patients with macular edema. Setting: Referral eye center. Patients: Forty-nine patients with the clinical diagnosis of diabetes or diabetic retinopathy and 25 patients with macular edema secondary to retinal vein occlusion, uveitis, epiretinal membrane formation, or cataract extraction. Main Outcome Measures: Correlation of optical coherence tomograms with slit-lamp biomicroscopy, fluorescein angiography, and visual acuity. Results: Optical coherence tomograms of cystoid macular edema closely corresponded to known histopathologic characteristics. Quantitative measurement of retinal thickness is possible because of the well-defined boundaries in optical reflectivity at the inner and outer margins of the neurosensory retina. Serial optical coherence tomographic examinations allowed tracking of both the longitudinal progression of macular thickening and the resolution of macular edema after laser photocoagulation. In patients with diabetic retinopathy, measurements of central macular thickness with optical coherence tomography correlated with visual acuity, and optical coherence tomography was more sensitive than slit-lamp biomicroscopy to small changes in retinal thickness. Conclusions: Optical coherence tomography appears useful for objectively monitoring retinal thickness with high resolution in patients with macular edema. It may eventually prove to be a sensitive diagnostic test for the early detection of macular thickening in patients with diabetic retinopathy.

Quantitative Assessment of Macular Edema With Optical Coherence Tomography

Optical coherence tomography (OCT) is a novel technique that allows cross-sectional imaging of the anterior and posterior eye. OCT has a resolution of approximately 10 microns, with extremely high sensitivity (approximately 10(-10) of incident light). OCT is analogous to computed tomography, which uses x-rays, magnetic resonance imaging, which uses spin resonance, or B-scan ultrasound, which uses sound waves, but OCT uses only light to derive its image. OCT is a noncontact, noninvasive system by which retinal substructure may be analyzed in vivo. OCT is useful in the evaluation of retinal pathologies and glaucoma. In retinal disease, entities such as macular holes, macular edema, central serous chorioretinopathy, retinal vascular occlusion and other factors have been examined. Separation between the posterior vitreous and retina, or lack thereof, are seen and quantitated. In glaucoma, retinal nerve fiber layer (NFL) thickness is measured at standardized locations around the optic nerve head. A circular scan produces a cylindrical cross-section of the retina, from which the NFL can be analyzed. In addition, radial scans through the optic nerve head are used to evaluate cupping and juxtapapillary NFL thickness. OCT, a new imaging technology by which the anterior and posterior segment are seen in cross-section, may permit the early diagnosis of glaucoma, and the early detection of glaucomatous progression.

Optical coherence tomography: a new tool for glaucoma diagnosis.

Quantitative Assessment of Macular Edema with Optical Coherence Tomography

Optical Coherence Tomography of Macular Holes

A Kerr-lens mode-locked Ti:Al 2 O 3 oscillator, optimized for minimal coherence length, is demonstrated as a high-power source for high-resolution optical coherence tomographic imaging. Dispersion compensation and heterodyne noise rejection are demonstrated to yield in situ images of biological tissues with 3.7-μm resolution and 93-dB dynamic range.

M. R. Hee

Papers

Quantitative Assessment of Macular Edema With Optical Coherence Tomography

Optical coherence tomography: a new tool for glaucoma diagnosis.

Quantitative Assessment of Macular Edema with Optical Coherence Tomography

Optical Coherence Tomography of Macular Holes

High-resolution optical coherence tomographic imaging using a mode-locked Ti:Al2O3 laser source