Atlas of Retinal OCT E-Book

Optical Coherence Tomography

Darin Goldman, Nadia K. Waheed, Jay S. Duker, Nadia K Waheed

• Publisher: Elsevier
• Year: 2017
• eBook ISBN: 9780323461221
• Topic: Medicine
• Subtopic: Opthalmology & Optometry

- Features more than 1, 000 superb illustrations depicting the full spectrum of retinal diseases using OCT scans, supported by clinical photos and ancillary imaging technologies.- Presents images as large as possible on the page with an abundance of arrows, pointers, and labels to guide you in pattern recognition and eliminate any uncertainty.- Includes the latest high-resolution spectral domain OCT technology and new insights into OCT angiography technology to ensure you have the most up-to-date and highest quality examples available.- Provides key feature points for each disorder giving you the need-to-know OCT essentials for quick comprehension and rapid reference.- An excellent diagnostic companion to Handbook of Retinal OCT: Optical Coherence Tomography, by the same expert author team of Drs. Jay S. Duker, Nadia K. Waheed, and Darin R. Goldman.

Part 1

Normal Optical Coherence Tomography

Outline

Section 1 Normal Optic Nerve

Section 2 Normal Retina

Section 3 Normal Choroid

Section 4 Normal Vitreous

Section 5 OCT: Artifacts and Errors

Section 1

Normal Optic Nerve

Outline

1.1 Normal Optic Nerve

1.1

Normal Optic Nerve

Carlos A. Moreira Neto, Carl Rebhun

Spectral domain OCT (SD-OCT) devices have two scan patterns to analyze the optic nerve head (ONH): volume scans and line scans.

Volume Scans

Volume scans acquire a volumetric set of data, centered at the ONH. It delineates the optic disc margin and optic disc surface contour and is segmented to obtain the retinal nerve fiber boundaries. Each device has its own scanning protocol. The Cirrus HD-OCT identifies the center of the optic disc and creates a 3.46-mm circle on this location and calculates the thickness of the retinal nerve fiber layer (RNFL). The Heidelberg Spectralis creates a cylindrical volume with a diameter of 3.4 mm through and around the ONH (Duker, Waheed & Goldman 2014). The Optovue RTVue's protocol for the ONH consists of a grid pattern with circular and radial scans that acquires a 4- × 4-mm volume around the optic nerve. Because different machines use circles of different diameters around the center of the ONH, the measurement of RNFL between machines is not comparable (Duker et al. 2014).

Retinal Nerve Fiber Layer Thickness (RNFL)

OCT devices calculate RNFL thickness as the distance between the internal limiting membrane and the outer aspect of the RNFL (Fig. 1).

FIG. 1 Normal peripapillary RNFL, neuroretinal rim thickness, and disc area measurements using SD-OCT.

Ganglion Cell Complex

The ganglion cell complex (GCC) consists of the thickness of three inner retinal layers: the NFL, the ganglion cell layer, and the inner plexiform layer. The scan is centered at the fovea, and the software presents the results as a color-coded map, comparing to a normative database (Fig. 2).

FIG. 2 Normal color-coded ganglion cell complex (GCC) thickness using SD-OCT.

Optic Nerve Morphology

SD-OCT devices also calculate optic nerve diameter, area, cup, and rim measurements (see Fig. 1). Each measurement varies according to age (Cavallotti et al. 2002) and ethnicity (Girkin 2008). According to Budenz et al. (2007), the mean RNFL thickness in a normal population is 100.1 µm. Thinner RNFL measurements were associated with older age. Caucasians had slightly thinner RNFL thickness than Hispanics or Asians. Persons with smaller optic disc areas also have thinner RNFL thickness.

Line Scans

Aiming to obtain a higher resolution visualization of structure and anatomic anomalies at the ONH, line scans provide a single or a series of high-resolution B-scans similar to the scans obtained in the macula (Fig. 3).

FIG. 3 Line scan of the ONH.

OC...

Table of contents

• Cover image
• Title Page
• Table of Contents
• Copyright
• Preface
• Contributors
• Acknowledgments
• Dedications
• Part 1 Normal Optical Coherence Tomography
• Part 2 Isolated Macular Disorders
• Part 3 Vasoocclusive Disorders
• Part 4 Uveitis and Inflammatory Disorders
• Part 5 Retinal and Choroidal Tumors
• Part 6 Trauma
• Part 7 Inherited Retinal Degenerations
• Part 8 Vitreous Disorders
• Part 9 Miscellaneous Retinal Disorders
• Index