Unprocessed real-time imaging of vitreoretinal surgical maneuvers using a microscope-integrated spectral-domain optical coherence tomography system

Abstract

Background: We have recently developed a microscope-integrated spectral-domain optical coherence tomography (MIOCT) device towards intrasurgical cross-sectional imaging of surgical maneuvers. In this report, we explore the capability of MIOCT to acquire real-time video imaging of vitreoretinal surgical maneuvers without post-processing modifications.

Methods: Standard 3-port vitrectomy was performed in human during scheduled surgery as well as in cadaveric porcine eyes. MIOCT imaging of human subjects was performed in healthy normal volunteers and intraoperatively at a normal pause immediately following surgical manipulations, under an Institutional Review Board-approved protocol, with informed consent from all subjects. Video MIOCT imaging of live surgical manipulations was performed in cadaveric porcine eyes by carefully aligning B-scans with instrument orientation and movement. Inverted imaging was performed by lengthening of the reference arm to a position beyond the choroid.

Results: Unprocessed MIOCT imaging was successfully obtained in healthy human volunteers and in human patients undergoing surgery, with visualization of post-surgical changes in unprocessed single B-scans. Real-time, unprocessed MIOCT video imaging was successfully obtained in cadaveric porcine eyes during brushing of the retina with the Tano scraper, peeling of superficial retinal tissue with intraocular forceps, and separation of the posterior hyaloid face. Real-time inverted imaging enabled imaging without complex conjugate artifacts.

Conclusions: MIOCT is capable of unprocessed imaging of the macula in human patients undergoing surgery and of unprocessed, real-time, video imaging of surgical maneuvers in model eyes. These capabilities represent an important step towards development of MIOCT for efficient, real-time imaging of manipulations during human surgery.

Fig. 1

Three-dimensional static rendering of Tano diamond-dusted membrane scraper brushing against a cadaveric porcine retina. Summed and averaged orthogonal MIOCT B-scans obtained through a flat contact lens are oriented over the corresponding summed voxel projection

Fig. 2

MIOCT B-scans acquired through the non-contact BIOM from a healthy human volunteer (a) and from a human patient undergoing surgery at a normal pause immediately following surgical maneuvers (b,c). A single, unprocessed B-scan from a healthy human volunteer demonstrates resolution of individual retinal layers (a). Multiple outer retinal bands can be resolved, corresponding to the external limiting membrane (ELM), inner segment–outer segment junction (IS-OS), retinal pigment epithelium–outer segment junction (RPE-OS), and retinal pigment epithelium (RPE). Following surgical hyaloid separation and internal limiting membrane peel for vitreomacular traction, a single unprocessed B-scan (b) demonstrates a free edge of peeled internal limiting membrane (*) along with persistence of unchanged subretinal fluid (arrow) and inner retinal elevation, which are visualized with higher resolution and less speckle artifact on the processed image (c)

Fig. 3

Single MIOCT B-scan frames from real-time unprocessed video imaging oriented perpendicular to a Tano diamond-dusted membrane scraper brushing against the retinal surface of a cadaveric porcine eye. These images were obtained through a flat contact lens. Significant inward deflection of the inner retinal surface can be observed (a–d; Supplemental Video 1), which is decreased with less intense brushing (e–h; Supplemental Video 2)

Fig. 4

Single MIOCT B-scan frames from real-time unprocessed video imaging oriented along the longitudinal axis of the Tano diamond-dusted membrane scraper brushing against the retinal surface of a cadaveric porcine eye. These images were obtained through the non-contact BIOM. A reflection of the shaft of the instrument, which is a complex conjugate artifact (asterisk), is observed (a–d; Supplemental Video 3). This artifact can be removed using an inverted imaging technique (e–h; Supplemental Video 4)

Fig. 5

Single MIOCT B-scan frames from real-time unprocessed video imaging (Supplemental Video 5) demonstrating intraocular forceps (highlighted with red lines) grasping and peeling a flap of cadaveric porcine superficial retinal tissue. These images were obtained through a flat contact lens. The retinal flap was created with a barbed MVR blade prior to imaging (not shown). The forceps can be seen peeling the flap to the right of the images, until the flap breaks free (asterisk)

Fig. 6

Single MIOCT B-scan frames from real-time unprocessed video imaging (Supplemental Video 6) demonstrating retinal changes during surgical separation of the posterior hyaloid face in a cadaveric porcine eye. These images were obtained through a flat contact lens. In this series, the vitreous cutter (not seen) placed over the optic nerve head was used to aspirate and engage the posterior hyaloid, which was then elevated anteriorly, resulting in a circumferentially spreading separation of the vitreous from its attachments to the retina. As the vitreous separates, a corresponding ridge of outwardly progressing retinal elevation (arrows) is observed