In vivo recumbent photoreceptor imaging using the first handheld adaptive optics optical coherence tomography probe

Abstract

Purpose : Conventional adaptive optics (AO) ophthalmic imaging is largely limited to cooperative adults who are able to sit upright and fixate for extended periods. Our handheld AO optical coherence tomography (HAOOCT) probe enables 3D visualization of photoreceptor cells in upright and recumbent subjects, further extending AO-OCT into clinical settings.

Methods : OpticStudio and SolidWorks were used to design custom optics and mechanics, respectively, for the compact wavefront sensor and lens-based spectral domain HAOOCT system. HAOOCT was designed to achieve 2.26 μm lateral resolution and 4.01 μm axial resolution. The final form factor of HAOOCT is approximately 22 x 18 x 5.2 cm with a total weight of 630 g (Fig. 1). HAOOCT volumes with 1° FOV were acquired with a volume rate of 2.3 Hz. Volumes with overlapping FOVs were registered and averaged. Consented healthy adult volunteers were imaged in both upright and recumbent postures at the Duke Eye Center.

Results : The photoreceptor mosaic was visualized in all volunteers under different experimental setups. The imaging results from two of these subjects are shown in Fig. 2. Subject A was imaged while seated and stabilized with a chin/forehead rest, with HAOOCT mounted on an ophthalmic translation stage. An averaged B-scan (linear scale) and en face maximum intensity projection (MIP) show the photoreceptor mosaic 3-5° from fovea (Fig. 2a-b). Subject B was directed to lay in a fully recumbent position on a reclined chair and imaged with HAOOCT in handheld operation. A single B-scan and en face MIP from an un-registered volume reveal the photoreceptor mosaic (Fig. 2c-d).

Conclusions : We achieved cone photoreceptor visualization in adult volunteers using HAOOCT in both stabilized and handheld configurations. This is the first demonstration of a handheld WFS-based AO ophthalmic system and the first attempt to collect AO-OCT volumes using a handheld system.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Figure 1. Photograph of HAOOCT probe.

 

Figure 2. HAOOCT B-scans and en face views of segmented regions in subject A (a-b) and B (c-d). En face views are MIPs of the cone IS/OS and S-cone region (dashed lines) indicated on a sample B-scan. B-scan location is denoted (solid red line) on its corresponding MIP. (a) Registered B-scan image using 7 registered volumes and its (b) corresponding MIP. (c) Single B-scan image and its (d) corresponding MIP. Scale bar, 100 μm.