Publication Exclusive: Intraoperative OCT benefits anterior segment surgeries

With FDA clearance of three intraoperative OCT systems over the past 2 years, the technology is rapidly moving from potential to practice.

These microscope-integrated systems — the En-Focus intrasurgical OCT system (Bioptigen, a division of Leica Microsystems), the Rescan 700 (Carl Zeiss Meditec) and the iOCT (Haag-Streit) — allow for real-time, high-quality imaging that can influence surgical decision-making and potentially contribute to achieving better outcomes in anterior segment surgery.

“We are learning the advantages and disadvantages of each system. It is very much in the early period,” Justis P. Ehlers, MD, said. Ehlers is the Norman C. and Donna L. Harbert Endowed Chair for Ophthalmic Research at Cole Eye Institute and has used the EnFocus, Rescan 700 and two microscope-integrated systems built for research. The Rescan 700, in particular, “was designed as a complete integrated unit. Ergonomically, it is difficult to tell there is an OCT added to the microscope. The footprint is identical,” he said.

In contrast, the EnFocus was initially built as a microscope add-on, allowing the user to fit it to a current microscope. But since last year when Bioptigen, a maker of OCT, was acquired by Leica, a maker of microscopes, “the technology has the potential to be integrated in an even more seamless way,” Ehlers said.

The iOCT system from Haag-Streit takes a different approach, according to Ehlers, in that it brings in the OCT through a camera port. “Thus, the overall change to the ergonomics is minimal,” he said. “But there are unique challenges with accessing the optical pathway through the side port.”

Usability and image quality

Although seamless integration with high value to patient outcomes is likely the ultimate goal of intraoperative OCT, two additional vital features from a systems standpoint are “usability and image quality,” Ehlers said. “A surgeon desires something that is fast and easy to direct to the area of interest for scanning. We also want to achieve high-quality images and high-quality feedback. The challenges around obtaining high-quality images in the operating room are so different than in clinic. You are dealing with factors such as blood and corneal edema that make the imaging environment suboptimal.”

The two areas of anterior segment surgery that hold the most promise for intraoperative OCT are lamellar keratoplasty and customizing IOL measurements, according to Ehlers. For deep anterior lamellar keratoplasty, “there is excitement about being able to visualize depth of dissection in real time and to identify the location of planes to create a successful big bubble,” he said. “Through enhancing the accuracy of big bubble creation and dissection, intraoperative OCT may also facilitate improved outcomes.”

Similarly, for Descemet’s membrane endothelial keratoplasty and Descemet’s stripping automated endothelial keratoplasty, “we have shown in some of our research that intraoperative OCT can be very helpful in identifying residual fluid between the graft and the host cornea,” Ehlers said. “This can have potential implications for interface haze and visual recovery time; intraoperative OCT may also play a role in dislocation rates of the grafts.”

OSN Cornea/External Disease Board Member Francis W. Price Jr., MD, believes the greatest application for intraoperative OCT to date has been with endothelial keratoplasty, either DSAEK or DMEK.

Click here to read the full cover story published in Ocular Surgery News U.S. Edition, March 25, 2016.