OSLI Retina

January/February 2013

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■ C L I N I C A L S C I E N C E ■ Identifying the Boundaries of Retinal Pigment Epithelial Detachments Using Two Spectral-Domain Optical Coherence Tomography Instruments Fernando M. Penha, MD, PhD; Giovanni Gregori, PhD; Zohar Yehoshua, MD; William J Feuer, MS; Philip J. Rosenfeld, MD, PhD BACKGROUND AND OBJECTIVE: To compare two INTRODUCTION spectral-domain optical coherence tomography (SDOCT) instruments in identifying the boundaries of retinal pigment epithelium detachment (PED). Retinal pigment epithelium detachments (PEDs) have been associated most commonly with age-related macular degeneration (AMD), central serous chorioretinopathy, and polypoidal choroidal vasculopathy.1 Historically, the diagnosis and follow-up of PEDs were based on imaging with fluorescein angiography (FA) and indocyanine green angiography (ICGA). More recently, optical coherence tomography (OCT) has proven useful for identifying and following PEDs.1,2 The introduction of spectral-domain OCT (SDOCT) instruments with high scanning speeds and dense scanning patterns covering a large retinal area has eliminated the need to interpolate between just six scans in time-domain technology and has led to a more reliable assessment of retinal thickness measurements.3-6 However, the accuracy of any retinal thickness measurement depends primarily on the accuracy of the segmentation algorithms that identify the retinal boundaries, which include the internal limiting membrane (ILM) and the retinal pigment epithelium (RPE). The currently available SD-OCT instruments each use a different proprietary algorithm. Several papers have recently analyzed various characteristics of these segmentation algorithms,7,8 particularly their reproducibility in a number of different conditions.9-16 The presence of a PED can present a challenge for a segmentation algorithm due to the deformation of the RPE.8,17 Accurate identification of the RPE layer is required to obtain an accurate retinal thickness measurement in the setting of PEDs.13,18 The impor- PATIENTS AND METHODS: 27 eyes were scanned with Cirrus and Spectralis SD-OCT instruments during a single visit. Two Cirrus scan patterns were used: the 512 × 128 and 200 × 200 covering a 6 × 6 mm (20° × 20°) area. The Spectralis scan pattern consisted of seven B-scans, averaged 51 times, covering a 30° × 5° area. The main outcome measures were the retinal thickness at the foveal center and the number of segmentation failures on the central B-scan. RESULTS: The Spectralis algorithm failed to follow the proper retinal contour in 25 eyes (92.6%), while the segmentation on the Cirrus instrument was successful in every central B-scan. Spectralis yielded greater retinal thickness measurements in all cases, and the average difference between Cirrus and Spectralis was 139 µm (P < .001). The intraclass correlation coefficient between the two Cirrus scan patterns was 0.998, and Cirrus versus Spectralis was 0.21. CONCLUSIONS: The Cirrus SD-OCT instrument identifies the appropriate segmentation boundaries in the presence PED. The Spectralis SD-OCT algorithm was unreliable in segmenting PEDs, leading to inaccurate retinal thickness measurements unless manual adjustments were performed. [Ophthalmic Surg Lasers Imaging Retina 2013;44:10-16.] From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida. Originally submitted December 9, 2012. Accepted for publication December 15, 2012. The research was supported by a grant from Carl Zeiss Meditec, Dublin, California, an unrestricted grant from Research to Prevent Blindness, NEI core center grant P30 EY014801 to the University of Miami, the Jerome A. Yavitz Charitable Foundation, the Macula Vision Research Foundation, Feig Family Foundation, the Gemcon Family Foundation, the Carl and Lily Pforzheimer Foundation, and the Emma Clyde Hodge Memorial Foundation. Address correspondence to Philip J. Rosenfeld, MD, PhD, Bascom Palmer Eye Institute, 900 NW 17th St., Miami, FL 33136. E-mail: prosenfeld@med.miami. edu. doi: 10.3928/23258160-20121221-06 10 Healio.com/OSLIRetina

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