Dynamic Intrasurgical Monitoring of Anterior Segment Tissue-Tool Interactions with Spectral Domain Microscope Integrated Optical Coherence Tomography

Abstract

 

Purpose

 

Optical coherence tomography (OCT) is a widely used imaging modality in clinical eye care. Intraoperative OCT has recently been described with promising reports of use during “pauses” in surgery. To progress towards truly interactive OCT guided surgery, OCT systems must be able to dynamically monitor tissue-tool interactions in real-time during surgery. The purpose of this study was to dynamically image anterior segment surgical maneuvers during cataract and Descemet stripping endothelial keratoplasty (DSEK) surgeries.

 

Methods

 

Under an IRB approved protocol, patients undergoing cataract or DSEK surgery consented to allow use of intrasurgical OCT. Surgeries were performed per usual standard technique. Microscope integrated OCT (MIOCT) with manual tracking was used for imaging. MIOCT uses a current generation commercial spectral domain OCT engine (865 nm center wavelength, 20 kHz A-scan rate, 7.3 µm transverse x 5 µm axial resolution in air). Manual tracking was used to rapidly move the OCT scans to regions of interest within the surgical field of view. To dynamically monitor tissue-tool interactions, serial B scans were acquired at an effective rate of 20 frames per second during select surgical maneuvers.

 

Results

 

Dynamic MIOCT imaging was attempted on 7 subject surgeries (5 cataract, 2 DSEK). In 5 out of 7 subjects, the intended tissue-tool interaction was successfully captured. These included interactions of the cornea with keratomes, irrigating and stripping cannulas, and air. Figure 1 shows clear corneal incision creation with a keratome (label is frame number - seconds). Figure 2 shows unfolding of an endothelial graft with air from a cannula. Dynamic attempts to capture maneuvers with large 3D spatial extents (phacoemulsification and capsulorrhexis) were less successful, though portions of the maneuvers could be identified in individual B scans within the series.

 

Conclusions

 

Spectral domain MIOCT with manual tracking can be used to dynamically monitor tissue-tool interactions in anterior segment surgeries. This is a necessary step towards dynamic OCT guided surgery. Successful efforts tended to be smaller maneuvers which could be captured using serial 2D B scans. Maneuvers with larger spatial excursions will likely require larger range, volumetric imaging with requisite increases in speed to allow real time presentation to the surgeon.

 

 

 

Keywords: 550 imaging/image analysis: clinical • 479 cornea: clinical science • 741 transplantation