In this surgical video, Dr. Riemann demonstrates the use of OCT imaging during pars plana vitrectomy.
Surgeon: Dr. Chris Reimann, Cincinnati Eye Institute, USA
Optical coherence tomography has become an essential tool for evaluating patients with vitreoretinal disease. Since its introduction by Dr. David Huang in 1991. OCT non-destructively images posterior segment anatomy in vivo, with sub-10 micron axial resolution, by measuring a time of light delay of optical B scan reflections. It has become standard of care for the management of a wide variety of vitreoretinal diseases. These include both wet and dry age-related macular degeneration, retinoarterial and venous occlusive diseases, vitreomacular traction syndrome, epiretinal membrane, macular hole, cystoid macular edema, diabetic macular edema, proliferative diabetic retinopathy, posterior hyaloidal traction syndrome, myopic maculoschisis, rhegmatogenous retinal detachment, and many others. Many of these diseases are amenable to attempted anatomical and visual rehabilitation with vitreoretinal surgery techniques. And OCT is instrumental in the pre and postoperative assessment of these patients. If we use OCT before and after surgery, the natural question arises of whether intraoperative OCT can be useful during vitreoretinal surgery. The purpose of this video is to describe the functionality of the Haag-Streit iOCT system, its integration with the surgical microscope, and some initial first impressions on how this new technology specifically may relate to the management of patients with vitreoretinal disease. The iOCT camera has a very low profile, and mounts directly to a beam splitter on the Haag-Streit Hi-R NEO 900 NIR microscope. A control unit is placed away from the surgical field on the back of the microscope. The touch screen user interface is mounted in a convenient and ergonomically sensible location for the operating surgeon. Near infrared tuned optics allow for the iOCT to be seamlessly integrated into and remain parfocal with the optical focal plane of the microscope. The iOCT is coupled to the surgical microscope’s focus and zoom, which greatly streamline the workflow of OCT image acquisition. The iOCT images the anterior segment without a contact lens. It performs high resolution macular scans through a direct contact lens. And can acquire stunning wide field line scans through the Haag-Streit near IR EIBOS2 non-contact wide angle viewing system. The scan rate of the iOCT is 10,000 A scans per second. The iOCT scan window is 4.2 millimeters deep, and between 5 and 30 millimeters wide, depending on zoom settings and the ancillary retinal imaging lenses being used. Single OCT line images, complete volume scans, and live streaming single A scan line video can be acquired at any time during the case, and are stored on an attached integrated hard drive. In this patient, a full thickness macular hole has caused a rhegmatogenous retinal detachment, evident clinically and on OCT. Under PFO, the retina is attached. After peeling ILM, the macular hole starts to reapproximate. After air-fluid exchange, a small amount of subfoveal posterior fluid remains. After carefully drying the macula with a soft tipped cannula, the subsensory fluid is gone, and the macular hole was closed. Intraoperative realtime OCT assessment of posterior segment anatomy may be beneficial in macula involving retinal detachment repair, macular hole surgery, as well as surgery for patients with vitreomacular traction syndrome and posterior hyaloidal traction syndrome. Anterior segment OCT of the pars plana after the cannulas are removed reveals an open 25-gauge sclerotomy with a small conjunctival bleb. This is in sharp contradistinction to this much more beveled sclerotomy, which is closed and does not have an overlying conjunctival bleb. Intraoperative optical coherence tomography, which is integrated into the operating microscope, is versatile and powerful imaging modality, which holds a great deal of promise for the future.
September 28, 2019