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Visible Light Optical Coherence Tomography (OCT) Quantifies Subcellular Contributions to Outer Retinal Band 4
Tingwei Zhang1, Aaron M Kho1, Glenn Yiu2
1Department of Biomedical Engineering, University of California Davis, Davis, California, USA.
Translational Vision Science & Technology
|May 18, 2021
Summary
Visible light optical coherence tomography (OCT) reveals that melanosomes in the retinal pigment epithelium (RPE) are key to the hyperreflective bands seen in the outer retina. This advanced OCT imaging helps understand retinal anatomy and disease.
Area of Science:
- Ophthalmology
- Biomedical Optics
- Retinal Imaging
Background:
- Clinical near-infrared (NIR) optical coherence tomography (OCT) visualizes hyperreflective bands in the outer retina.
- The precise subcellular origins of these bands, particularly the outermost (4th) band, remain incompletely understood.
- Distinguishing between the retinal pigment epithelium (RPE) and Bruch's membrane (BM) contributions is crucial for interpreting retinal structure.
Purpose of the Study:
- To utilize visible light optical coherence tomography (OCT) for high-resolution investigation of subcellular reflectivity within the outer retinal band 4.
- To identify the specific anatomical layers and cellular components responsible for the hyperreflective signals observed.
- To compare findings with current near-infrared (NIR) OCT imaging capabilities.
Main Methods:
- Employed visible light OCT with 1.0 µm axial resolution in 19 healthy human subjects (28 eyes).
- Quantified topographical variations in RPE thickness, BM thickness, and RPE reflectivity across the macula.
- Developed and applied a method for correcting RPE multiple scattering to refine BM thickness measurements.
Main Results:
- Consistently depicted two foveal and three extrafoveal hyperreflective zones within band 4.
- RPE thickness decreased with eccentricity; no significant topographical BM thickness variations were observed.
- Visible light OCT signal intensity within the RPE was concentrated apically and attenuated more in the fovea, suggesting melanosome involvement.
Conclusions:
- Morphometric analysis of RPE and BM bands aligns with established ocular anatomy.
- Apical weighting of RPE reflectivity indicates melanosomes are the primary source of backscattering and signal attenuation.
- Visible light OCT successfully deciphers reflectivity contributions to outer retinal band 4, enhancing understanding beyond commercial OCT systems.
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