4D Intrasurgical Monitoring and Guidance of Anterior Segment Surgeries with Swept-Source Microscope Integrated Optical Coherence Tomography

Abstract

 

Purpose

 

Spectral-domain microscope integrated optical coherence tomography (MIOCT) systems allow 2D visualization of a few locations during surgery. This requires that the B-scan be repeatedly matched to the region or tool of interest. Imaging the entire spatial extent of the surgical field (3D) would allow the surgeon to monitor the entire field in real time without constraints imposed by single B-scan imaging. The purpose of this study was to dynamically image and guide anterior segment surgical maneuvers in 4D (3D + time) using swept-source MIOCT (SS-MIOCT).

 

Methods

 

Under an IRB approved protocol, 5 patients undergoing anterior segment surgeries - 2 cataracts, 2 deep anterior lamellar keratoplasties (DALK), and 1 Descemet’s stripping automated endothelial keratoplasty (DSAEK) triple - consented to allow use of intrasurgical OCT. SS-MIOCT with custom tracking hardware and a swept-frequency source centered at 1040 nm were used for imaging (A-scan rate: 100 kHz, volume rate: 2 Hz, 102 dB sensitivity, 12x12x7.4 mm imaging range). Volumetric processing was performed and displayed in real-time. Surgeries were performed per surgeons’ standard technique complemented by feedback from OCT images.

 

Results

 

All intended 4D tissue-tool interactions were successfully monitored (Figures 1 and 2). Specific surgical maneuvers were actively guided by OCT. These included dynamic wound testing at the conclusion of cataract surgery, guiding needle placement during DALK, and assessment of graft-host interface fluid during DSAEK.

 

Conclusions

 

SS-MIOCT was used to dynamically monitor and guide specific anterior segment surgical maneuvers. However, surgical maneuvers exceeding the axial and lateral imaging range of the system (instrument motions carrying the eye out of field) did affect the ability to image some maneuvers. Further development of SS-MIOCT 4D imaging during anterior segment surgeries will elucidate its role for improving surgical guidance and ultimately clinical outcomes.  

 

Figure 1: A) 3D, B) B-scan, and C) summed-voxel projection (SVP) images are shown in time sequence for graft unfolding during DSAEK (red: cornea, yellow: graft, blue: iris).

 

 

Figure 2: A) 3D and B-scan images for wound testing at the conclusion of cataract surgery (red: Weck-Cel, yellow: incision, *: artifact). B) 3D and B-scan images for needle depth guidance during DALK (blue: needle).