Ophthalmic robotically aligned optical coherence tomography with interchangeable imaging modules

Abstract

Purpose : Optical coherence tomography (OCT) is the standard-of-care ophthalmic imaging modality for the front and back of the eye. We recently introduced robotically aligned OCT (RAOCT) for ophthalmic imaging but were limited to either the anterior chamber or retina. Here we present a flexible RAOCT platform that allows for interchangeable imaging modules for specific targets of interest.

Methods : We based our swept-source OCT engine (Fig. 1A) on a VCSEL with electronically switchable A-scan rate and MZI lengths (Thorlabs; λ₀ = 1045nm; 250, 500 kHz, 1 MHz; 12, 6, 3 mm imaging depths). The reference arm contains two stages, a motorized 100 mm optical delay line (Oz Optics) for module path length compensation and a 12.7 mm voice coil motor (H2W) for dynamic axial motion compensation.
The modular OCT imaging platform consists of a scan head and interchangeable modules (Fig. 1B-E) wherein the total mass of the scan head and a given imaging module was kept within the robot payload limit (Universal Robots, UR3e, 3 kg). Both modules include OCT imaging optics, integrated pupil cameras, and pupil illumination (Fig. 1D-E). The scan head includes a liquid lens for Diopter correction, a 2D MEMs mirror for fast patient motion compensation, two orthogonal galvos imaged on to one another, and an F-mount flange as a fixed module mounting point. We designed the anterior chamber (AC) module with a field-of-view (FOV) of 16 mm while the retinal module expands RAOCT to beyond 40° FOV.

Results : Figure 2 illustrates imaging with this new system of a whole eye phantom (Rowe). Figures 2D-E demonstrates volumetric imaging of the entire phantom anterior chamber at 6 mm imaging depth and 500 kHz A-scan rate. Figures 2F-G demonstrates volumetric imaging of the phantom retina at 3 mm imaging depth and 1 MHz A-scan rate.

Conclusions : We have demonstrated AC and retinal imaging modules for RAOCT. This flexible design enables the ability to develop additional imaging modules for new robotically aligned applications.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Interchangeable RAOCT Design. A) System schematic B&C) Scan head optical and mechanical design D&E) Mechanical designs for AC and retinal imaging modules.

 

RAOCT Imaging A) Interchangeable RAOCT system with AC imaging module B) Retinal imaging module C) Whole eye phantom D) OCT volume rendering of phantom AC (500 kHz, 6mm depth) E) B-scan from D F) OCT volume rendering of phantom retina (1 MHz, 3mm depth) F) B-scan from E