Article

Optical Coherence Tomography of the Anterior Segment

Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
The ocular surface (Impact Factor: 4.21). 08/2008; 6(3):117-27. DOI: 10.1016/S1542-0124(12)70280-X
Source: PubMed

ABSTRACT Perhaps no diagnostic technology has emerged as rapidly in ophthalmology as optical coherence tomography (OCT). A single clinical device for this noninvasive imaging technique was first released in 1996, and now at least ten clinical devices are available. Although the first clinical anterior segment OCT was marketed only 2 years ago, a substantial amount of work has been done using modified retinal imagers or prototype laboratory-based imagers. In this review, we discuss OCT imaging primarily of the cornea. We also highlight previous and current publications on nonclinical and clinical uses of the device to illustrate how anterior segment OCT can be used to understand corneal structure and function in health and disease.

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    • "OCT is based on low-coherence interferometry to measure the amplitude of light backscattered by the sample being imaged [1] [2] [3] [4]. The most significant impact of OCT is in ophthalmology for in situ examination of the pathologic changes of the retina [5] [6] [7] [8] and measurement of the dimensions of the anterior chamber of the eye [9] [10]. OCT has also been established in a variety of other biomedical applications [11] and for material characterization [12] [13]. "
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    ABSTRACT: Full-field optical coherence microscopy (FF-OCM) is a recent optical technology based on low-coherence interference microscopy for semi-transparent sample imaging with ~ 1 μm spatial resolution. FF-OCM has been successfully applied to three-dimensional imaging of various biological tissues at cellular-level resolution. The contrast of FF-OCM images results from the intensity of light backscattered by the sample microstructures. This contrast mechanism, based on refractive index changes, provides information on the internal architectural morphology of the sample. In this paper, we present a multimodal FF-OCM system, capable of measuring simultaneously the intensity, the power spectrum and the phase-retardation of light backscattered by the sample being imaged. Tomographic fluorescence-based images can also be produced by coupling to the FF-OCM set-up a fluorescence microscopy system with structured illumination. Fluorescence targeted probes can be used to identify molecular components of subcellular scattering structures. Compared to conventional FF-OCM, this multimodal system provides enhanced imaging contrasts at the price of a moderate increase in experimental complexity and cost.
    05/2013; DOI:10.1063/1.4809702
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    • "Providing high-resolution, cross-sectional images of internal biological microstructures, OCT was first used by ophthalmologists to image the retina [2] [3] [4] and then more recently the anterior segment [5] [6] [7]. It has also been used to investigate the results of refractive surgeries in situ [8] [9] [10] and screen donor corneas for previous refractive surgeries such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) [11] [12] [13]. "
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    ABSTRACT: Purpose. To evaluate Fourier-domain optical coherence tomography (FD-OCT) as an adjunct to traditional slit lamp examination of donor corneas with suspected Anterior Stromal Opacities. Methods. Seven corneas suspected of having anterior stromal opacities by slit lamp examination were evaluated with FD-OCT. Each cornea was evaluated to confirm the presence of opacity and, if present, the depth of opacity was measured. Results. The opacity depth ranged from 82 μm to 624 μm. The initial slit lamp impressions of five of the seven corneas were confirmed by OCT. In two corneas, the OCT findings were different from the initial slit lamp impressions. Slit lamp examination of the first cornea gave the impression of anterior stromal scarring, but OCT showed that the opacity was limited to the epithelium. Slit lamp examination of the second cornea suggested opacity limited to the epithelium, but OCT identified significant sub-Bowman's scarring. In all cases, the Eye Bank Technicians reported that the location and depth of corneal opacity were more sharply defined by OCT than by slit lamp. Conclusion. The high resolution of OCT makes it easier to determine the location of corneal opacities compared to slit lamp examinations. This enhanced visualization can improve decisions regarding transplant suitability of donor corneas.
    Journal of Ophthalmology 03/2013; 2013:397680. DOI:10.1155/2013/397680 · 1.94 Impact Factor
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    • "OCT is based on low-coherence interferometry to measure the amplitude of light backscattered by the sample being imaged [1] [2] [3] [4]. The most significant impact of OCT is in ophthalmology for in situ examination of the pathologic changes of the retina [5] [6] [7] [8] and measurement of the dimensions of the anterior chamber of the eye [9] [10]. OCT has also been established in a variety of other biomedical applications [11] and for material characterization [12] [13]. "
    Selected Topics in Optical Coherence Tomography, 02/2012; , ISBN: 978-953-51-0034-8
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