Purpose
To evaluate the use of an intraoperative SD-OCT system that attaches to an ophthalmic operating microscope (OPMI) for on-demand OCT guided anterior segment (AS) surgery.
Methods
We used a commercial prototype (Bioptigen, Inc.) that consists of a compact OCT delivery console connected to a transportable cart that houses an SD-OCT engine, a computer for image acquisition and processing and a monitor for image display. The system provides near 9µm axial resolution over an imaging depth of 15.4 mm in air. The scanning console can attach to several commercial OPMI models and includes a proprietary microscope objective with a focal length of 175 mm, a two axes OCT scanning mechanism and the optics to combine the OCT scanning beam with the illumination and viewing paths of the host OPMI. The delivery console is setup by removing the original microscope objective lens from the host OPMI and by securing the scanning head enclosure to the dovetail connection of the host OPMI. Prior to surgery, the OCT delivery unit was attached to the OPMI and the cart was deployed near the bedside so that intraoperative OCT images of the surgical site could be displayed in real-time to the surgeon using the computer monitor.
Results
Under an IRB approved protocol, 4 patients who underwent AS surgical procedures including cataract and DSAEK surgeries were imaged intraoperatively. Surgeries were uneventful. The system enabled displaying the images to the surgeon without interrupting the surgical maneuvers or blocking the OPMI view. The distance of 167 mm between the microscope objective and the patient eye provided enough room for the surgeon to operate comfortably. The compact surgical OCT interface did not interfere with the sterile field and the standard operations performed by the surgical staff. Pre-operatively, the system enabled to confirm that the AS did not show any abnormality. Throughout DSAEK surgeries, the long imaging depth and the volumetric capability of the SD-OCT system enabled to verify optimal adhesion of the entire graft to the host cornea in 3D. Throughout cataract surgery the system enabled to verify the integrity of the capsule and the final position of the intraocular lens.
Conclusions
The intraoperative SD-OCT system can be easily and safely used to assist the surgeon for AS surgeries. This tool has potential to improve the outcome of DSAEK and help with challenging cases of cataract surgery.