optical coherence tomography (oct) gella laxmi 2009phxf013p
TRANSCRIPT
![Page 1: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/1.jpg)
Optical Coherence Tomography (OCT)
Gella Laxmi2009PHXF013P
![Page 2: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/2.jpg)
Introduction
![Page 3: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/3.jpg)
OCT
Determining and visualizing structure that absorb and scatter light
Noninvasive in vivo analysis of retinal tissue
1 mm 1 cm 10 cm
Penetration depth (log)
1mic
10mic
100micronm
Resolution (log)
Ultrasound
OCTConfocalmicroscopy
Standardclinical
CT and MRI
![Page 4: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/4.jpg)
Principle
Michelson Interferometer
![Page 5: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/5.jpg)
Beam splitter
Diode 820
Reference beam
Patients eye
DVD
OCT software
Detector
![Page 6: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/6.jpg)
Combination of multiple A scans to produce…..
![Page 7: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/7.jpg)
Time Domain OCT
![Page 8: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/8.jpg)
CHORIOCAPILLARISCHORIOCAPILLARIS
NFLNFLGCLGCL
FOVEOLAFOVEOLA
IPLIPL
INLINL
OPLOPL
ONLONL
RPERPE PHOTORECEPTORSPHOTORECEPTORS ELMELM
Spectral Domain OCT
![Page 9: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/9.jpg)
Features of SD-OCT
Better anatomic representation
High resolution (6 microns)
Fewer movement artifacts
Live cross-sectional movies of various details
High Signal to noise ratio
Scanning speed 25, 000 A-scans per second
3D imaging
![Page 10: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/10.jpg)
Vs
Histological retina Vs SD-OCT
![Page 11: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/11.jpg)
Retinal Structures on SD-OCT
Horizontally oriented structures – hyperreflective
Vertically oriented structures (layers containing nuclei) – hypo reflective
![Page 12: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/12.jpg)
Choriocapillaris: Innermost limit of the
vascular layer of the eye
Thin and hyper-reflective
layer
Larger vessels of choroid
– hyporeflective
Inconsistently identified
Bruch’s membrane: Not visible on SD-OCT
VV
VVV
CCRPECCRPE
V
CCRPE
![Page 13: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/13.jpg)
Retinal Pigment Epithelium:
RPE-CC complex divided into 3 parallel strips
2 are thick, hyperreflective separated by thin
hyporeflective line
Verhoef’s membrane
![Page 14: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/14.jpg)
Photoreceptors:
Rods and cones contain inner and
outer parts
Inner part: nuclei (outer nuclear layer)
Outer part: inner and outer segment
Connection b/w inner and outer
segment forms a hyper-reflective strip
(result of diff in RI)
Sharply raised at the foveola
External limiting membrane
![Page 15: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/15.jpg)
Outer plexiform layer: Visual cells connect to the bipolar cells
Horizontal axons of the horizontal cells
Hyper-reflective strip
Inner nuclear layer: Nuclei of bipolar, horizontal, muller and amacrine
cells
Hyporeflective layer
![Page 16: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/16.jpg)
Inner plexiform layer: Synapses b/w ganglion cells and amacrine cells Hyper-reflective owing to their horizontal
structure
Ganglion cell layer Bulky cells are multilayered Hyper-reflective
Nerve fiber layer Nerve axons Very high reflective layer
RNFLGCLIPL
![Page 17: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/17.jpg)
Internal limiting membrane
Difficult to distinguish
Hyaloid and vitreous
Various pathologic structures clearly visible
![Page 18: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/18.jpg)
Reporting SD-OCT
Comment on each layer
Reflectivity
Morphological features
Measurements of thickness
![Page 19: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/19.jpg)
Take-home message
Retinal anatomy and virtual histology can be
studied with the SD-OCT
The SD-OCT shows more detail at the
vitreoretinal interface, and there is better
delineation of all retinal layers
![Page 20: Optical Coherence Tomography (OCT) Gella Laxmi 2009PHXF013P](https://reader030.vdocuments.site/reader030/viewer/2022033023/56649f455503460f94c668b5/html5/thumbnails/20.jpg)
References
Bruno Lumbroso. SD-OCT Reveals Details of Posterior Segment Structures. Cataract & refractive surgery today Europe. June 2008. Pg 27-28
Wolfgang Drexler, et al. State-of-the-art retinal optical coherence tomography. Progress in retina and eye research. 2008.Jan; 27(1): 45-88
Bruno Lumbroso, et al. Understanding Spectral OCT. I.N.C Innovation-News-Communication. 2007.
Michael R. Hee, et al. Optical Coherence Tomography of the Human Retina. Arch Ophthalmol. 1995; 113: 325-332.