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Depth-multiplexing spectral domain OCT for full eye length imaging with a single modulation unit

Guanghan Meng, Xue Dong, Andrew Zhang, Fabio Feroldi, Austin Roorda, Laura Waller

TL;DR

A novel DM-SD-OCT approach that utilizes a single light modulation unit for depth encoding and captures images at multiple depths within the eye simultaneously with a single line scan camera, then computationally demix the contributions from different depths.

Abstract

Clinical measurement of a patient's axial eye length is emerging as a crucial approach to track progression and monitor management of myopia. However, the preferred method for such measurements is swept-source OCT, whose cost prohibits broad use, especially in lower-income communities. Spectral domain (SD) OCT is a more affordable option, but it has limited imaging depth range, so is not suitable for full eye length measurement. Depth-multiplexing (DM) techniques for SD-OCT provide a workaround by capturing images at multiple depths within the eye. However, these methods typically require multiple light modulation units or detectors for simultaneous imaging across depths, adding complexity and cost. In response, we propose a novel DM-SD-OCT approach that utilizes a single light modulation unit for depth encoding. We capture images at multiple depths within the eye simultaneously with a single line scan camera, then computationally demix the contributions from different depths. Here, we demonstrate acquisition and demixing of signals from three distinct depths within the eye and validate experimentally in human subjects. Our method thus offers a cost-effective solution for comprehensive eye length measurement in clinical myopia research.

Depth-multiplexing spectral domain OCT for full eye length imaging with a single modulation unit

TL;DR

A novel DM-SD-OCT approach that utilizes a single light modulation unit for depth encoding and captures images at multiple depths within the eye simultaneously with a single line scan camera, then computationally demix the contributions from different depths.

Abstract

Clinical measurement of a patient's axial eye length is emerging as a crucial approach to track progression and monitor management of myopia. However, the preferred method for such measurements is swept-source OCT, whose cost prohibits broad use, especially in lower-income communities. Spectral domain (SD) OCT is a more affordable option, but it has limited imaging depth range, so is not suitable for full eye length measurement. Depth-multiplexing (DM) techniques for SD-OCT provide a workaround by capturing images at multiple depths within the eye. However, these methods typically require multiple light modulation units or detectors for simultaneous imaging across depths, adding complexity and cost. In response, we propose a novel DM-SD-OCT approach that utilizes a single light modulation unit for depth encoding. We capture images at multiple depths within the eye simultaneously with a single line scan camera, then computationally demix the contributions from different depths. Here, we demonstrate acquisition and demixing of signals from three distinct depths within the eye and validate experimentally in human subjects. Our method thus offers a cost-effective solution for comprehensive eye length measurement in clinical myopia research.
Paper Structure (4 equations, 4 figures, 1 table)

This paper contains 4 equations, 4 figures, 1 table.

Figures (4)

  • Figure 1: Principle of depth-multiplexing spectral domain optical coherence tomography (DM-SD-OCT) demonstrated in simulation. (A) Image of a model eye (Rowe Technologies Inc.) obtained with Zeiss IOL Master as the input into the simulation pipeline. Our setup has three reference arms, each focused at a different depth (indicated by the blue, orange and purple arrowheads). (B) We capture a single frequency-encoded B scan; here, we show the B scan cross-correlation term (left) and its Fourier transform along the transverse axis. The colored boxes denote the cropped spectra that correspond to each of the three reference arm depths. (C) Reconstructed images from the three reference depths.
  • Figure 2: Design of the DM-SD-OCT setup.
  • Figure 3: Characterization of the DM-SD-OCT system.
  • Figure 4: Experimental validation in a myopic adult. (A) DM SD-OCT result without frequency demixing, using 3 reference arms depths targeting at the corena, pupil and the retina, respectively. (B) Frequency demixed image with correct axial length information.