Spaide RF, Curcio CA. Anatomical correlates to the bands seen in the outer retina by optical coherence tomography: literature review and model

Vitreous-Retina-Macula Consultants of New York, New York, USA.
Retina (Philadelphia, Pa.) (Impact Factor: 3.24). 07/2011; 31(8):1609-19. DOI: 10.1097/IAE.0b013e3182247535
Source: PubMed


To evaluate the validity of commonly used anatomical designations for the four hyperreflective outer retinal bands seen in current-generation optical coherence tomography, a scale model of outer retinal morphology was created using published information for direct comparison with optical coherence tomography scans.
Articles and books concerning histology of the outer retina from 1900 until 2009 were evaluated, and data were used to create a scale model drawing. Boundaries between outer retinal tissue compartments described by the model were compared with intensity variations of representative spectral-domain optical coherence tomography scans using longitudinal reflectance profiles to determine the region of origin of the hyperreflective outer retinal bands.
This analysis showed a high likelihood that the spectral-domain optical coherence tomography bands attributed to the external limiting membrane (the first, innermost band) and to the retinal pigment epithelium (the fourth, outermost band) are correctly attributed. Comparative analysis showed that the second band, often attributed to the boundary between inner and outer segments of the photoreceptors, actually aligns with the ellipsoid portion of the inner segments. The third band corresponded to an ensheathment of the cone outer segments by apical processes of the retinal pigment epithelium in a structure known as the contact cylinder.
Anatomical attributions and subsequent pathophysiologic assessments pertaining to the second and third outer retinal hyperreflective bands may not be correct. This analysis has identified testable hypotheses for the actual correlates of the second and third bands. Nonretinal pigment epithelium contributions to the fourth band (e.g., Bruch membrane) remain to be determined.

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Available from: Christine A Curcio, Aug 17, 2015
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    • "This procedure allowed an overlap of at least 2 degrees of the horizontal and vertical images. Prior to each acquisition, the focus depth was adjusted to the region corresponding to the ellipsoid and interdigitation zones (formerly called the inner segment/outer segment (IS/OS) junction and cone outer segment tip (COST) line [29, 30]) in the OCT images. The resulting images were stitched together by superimposing retinal vessel landmarks with an image editing software (Photoshop, Adobe Corporation, Mountain View, CA; GIMP, The GIMP Development Team; Image J, National Institute of Health, Bethesda, MD). "
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    • "This allowed us to confirm the location of the inner segment and outer segment (Fig. 2G and H) each corresponding to two bands of different reflectance. This interpretation is consistent with that recently proposed by Spaide and Curcio for the human peripheral retina, obtained after comparison of histological findings from dozens of publications with SD-OCT data [25]. For the inner segment, the two bands most likely match to myeloid and ellipsoid [26]. "
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