Intrasurgical Human Retinal Imaging With Manual Instrument Tracking Using a Microscope-Integrated Spectral-Domain Optical Coherence Tomography Device

Abstract

Purpose: To characterize the first in-human intraoperative imaging using a custom prototype spectral-domain microscope-integrated optical coherence tomography (MIOCT) device during vitreoretinal surgery with instruments in the eye.

Methods: Under institutional review board approval for a prospective intraoperative study, MIOCT images were obtained at surgical pauses with instruments held static in the vitreous cavity and then concurrently with surgical maneuvers. Postoperatively, MIOCT images obtained at surgical pauses were compared with images obtained with a high-resolution handheld spectral-domain OCT (HHOCT) system with objective endpoints, including acquisition of images acceptable for analysis and identification of predefined macular morphologic or pathologic features.

Results: Human MIOCT images were successfully obtained before incision and during pauses in surgical maneuvers. MIOCT imaging confirmed preoperative diagnoses, such as epiretinal membrane, full-thickness macular hole, and vitreomacular traction and demonstrated successful achievement of surgical goals. MIOCT and HHOCT images obtained at surgical pauses in two cohorts of five patients were comparable with greater than or equal to 80% correlation in 80% of patients. Real-time video-imaging concurrent with surgical manipulations enabled, for the first time using this device, visualization of dynamic instrument-retina interaction with targeted OCT tracking.

Conclusion: MIOCT is successful for imaging at surgical pauses and for real-time image guidance with implementation of targeted OCT tracking. Even faster acquisition speeds are currently being developed with incorporation of a swept-source MIOCT engine. Further refinements and investigations will be directed toward continued integration for real-time volumetric imaging of surgical maneuvers.

Translational relevance: Ongoing development of seamless MIOCT systems will likely transform surgical visualization, approaches, and decision-making.

Keywords: OCT; human imaging; intraoperative; microscope-integrated; microscope-mounted; real-time; spectral-domain optical coherence tomography; tracking; vitreoretinal surgery.

Figure 1

Illustration comparing the use of HHOCT and MIOCT. HHOCT (A) requires a full pause in surgery, removal of the microscope away from the surgical field, and placement of a portable OCT scanner with a sterile wrap over the eye to obtain images viewed on a separate computer screen. In contrast, MIOCT (B) is integrated into the surgical microscope, enabling OCT acquisition simultaneous with ongoing surgical manipulations. Instrument-retina interactions can only be imaged with MIOCT.

Figure 2

Retinal projection (top) of intraocular internal limiting membrane forceps overlying the retinal surface with dashed white lines designating the location of the extracted B-scans. Individual B-scan images (middle and lower) demonstrate complete shadowing under the metal instrument, with different shadowing patterns corresponding to different contours of the imaged instrument. The larger images were denoised with postprocessing algorithms; the smaller insets comprise the corresponding live, non-postprocessed images that were viewable by the research team intraoperatively in real time.

Figure 3

Retinal projection (left) of a diamond dusted membrane scraper overlying the retinal surface and an individual B-scan (right) demonstrating the instrument overlying the retina with complete shadowing through the diamond-dusted tip (D) and the dense metal shaft (P) but near total visibility through the bare silicone portion of the instrument tip (S). An epiretinal membrane is clearly identified on the B-scan image, which was obtained prior to membrane peeling. The tip of the instrument appears to extend into the retina; however, this is a mirror image artifact caused by the instrument's position, which is above the zero delay line of the SDOCT and also well above the retinal surface. The larger image was denoised with postprocessing algorithms; the smaller inset comprises the corresponding live, non-postprocessed image that was viewable by the research team intraoperatively in real-time.

Figure 4

Single MIOCT B-scan frames from real-time video imaging (see Supplemental Video 1) targeted using a dynamic OCT tracking system to the longitudinal axis of the diamond-dusted membrane scraper brushing against the retinal surface during epiretinal membrane removal. The larger images were denoised with post-processing algorithms; the smaller insets comprise the corresponding live, non-postprocessed images that were viewable by the research team intraoperatively in real-time.