The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography

Abstract

PurposeOptical coherence tomography's (OCT) third outer retinal band has been attributed to the zone of interdigitation between RPE cells and cone outer segments. The purpose of this paper is to investigate the structure of this band with adaptive optics (AO)-OCT.MethodsUsing AO-OCT, images were obtained from two subjects. Axial structure was characterized by measuring band 3 thickness and separation between bands 2 and 3 in segmented cones. Lateral structure was characterized by correlation of band 3 with band 2 and comparison of their power spectra. Band thickness and separation were also measured in a clinical OCT image of one subject.ResultsBand 3 thickness ranged from 4.3 to 6.4 μm. Band 2 correlations ranged between 0.35 and 0.41 and power spectra of both bands confirmed peak frequencies that agree with histologic density measurements. In clinical images, band 3 thickness was between 14 and 19 μm. Measurements of AO-OCT of interband distance were lower than our corresponding clinical OCT measurements.ConclusionsBand 3 originates from a structure with axial extent similar to a single surface. Correlation with band 2 suggests an origin within the cone photoreceptor. These two observations indicate that band 3 corresponds predominantly to cone outer segment tips (COST). Conventional OCT may overestimate both the thickness of band 3 and outer segment length.

Three-Dimensional Adaptive Optics–Assisted Visualization of Photoreceptors in Healthy and Pathologically Aged Eyes

“…In healthy individuals, the bright spots at the height of the PR inner segment-outer segment (IS/OS) junction and from the cone OS tips (COST) result in a dense pattern in AO-OCT en face images, which actually represents the PR mosaic. [19][20][21][22][23][24][25] This mosaic is similar to that obtained with AO-SLO and AO fundus camera (AO-FC). 20,22,26 In contrast to the latter modalities, AO-OCT has the advantage of a significantly higher axial resolution (more than an order of magnitude) and the ability to create full threedimensional volumetric image data of the retina.…”

Directional optical coherence tomography reveals melanin concentration-dependent scattering properties of retinal pigment epithelium

“…In albino mice, which lack melanin in RPE cells, a thin highly reflective band corresponding to Bruch's membrane (BrM) appears posterior to IS/OS. The mouse retina layer assignments presented here are based on our understanding of the cellular origins of light scattering in the human retina presented by Jonnal et al 38,39 and correlations with mouse retinal histology. Figure 3 shows directional reflectivity profiles measured for four major retinal layers of three mice strains.…”

Intraframe motion correction for raster-scanned adaptive optics images using strip-based cross-correlation lag biases

“…Recent studies of the anatomical origins and properties of the outer retinal bands have shown that they are broader than would be predicted by the thin reflectors hypothesized to exist at IS/OS and COST [ 36 ], and that one of the factors in their broader appearance may be the axial staggering of surfaces among neighboring cells combined with lateral blur [ 32 , 37 ]. Table 1 shows how estimates of this axial staggering may depend upon the chosen method of flattening.…”