Session Title: Imaging I
Session Date/Time: Friday 18/09/2015 | 08:00-09:30
Paper Time: 08:56
First Author: : L.Lytvynchuk AUSTRIA
Co Author(s): : C. FalknerRadler C. Glittenberg S. Binder
PURPOSE:To visualise tips of vitreoretinal instruments during pars plana virectomy (PPV) with the use of intraoperative spectral domain optic coherence tomography (iSD-OCT) in oder to assess their position relatively to the retina and avoid trauma.
Department of Ophthalmology, Rudolf Foundation Clinic, Juchgasse 25, A-1030, Vienna, Austria, tel.: 43-1-71165-4638, -94678, fax: 43-1-71165-4609
First commercially available intraoperative SD-OCT RESCAN 700 (Zeiss, Oberkochen, Germany) was used to visualise the tips of the microsurgical instruments (light-pipe, vitreotome, forceps, cannulas, Tano scraper etc.) during pars plana vitrectomy due to retinal detachment (RD) - 10 cases, and epiretinal membrane (ERM) - 12 cases. For imaging a video recording system CALLISTO eye 3.2 was used with following parameters of OCT: scan length of 6 mm (512x128 cube), scan depth 2 mm, wavelength - 840 nm, scan mode cross-hair, scanning speed - 27.000 A-scans per second. Two imaging modes were recorded: video and images. Tips of the instruments were caught by the cross-hair scans while being positioned close to the retina surface. Collected data were analysed postoperatively using ImageJ software.
All instruments’ tips used during PPV were visualised with the use of iSD-OCT except light-pipe as it was always positioned away from the retina and scan range. Instruments with steel made tips are highly hyper reflective and were clearly visible on iSD-OCT scans. Silicone tips of cannulas and Tano scraper showed middle reflectivity. In 4 RD cases (40%) it was difficult to trace vitreotome and forceps in front of detached floating retina. Retinal reattachment with heavy liquids facilitated the imaging of the instruments. In 2 cases of ERM removal (15%) imaging of end-gripping forceps was not able due to antero-posterior direction of membrane peeling where the forceps went out of the range of scan. Mostly oblique position of all instruments relatively to retinal surface and perpendicular scan plane to the retina resulted in oblique cross-section of the instruments’ tips. Intraoperative SD-OCT was able to visualise the jaws of the scissors and forceps as separate parts. The distance between the retina and instruments’ tip was easily assessed and kept save.
Intraoperative SD-OCT with Rescan 700 is able to detect in general all vitreoretinal instruments while working close to the retinal surface due to hyper-reflective materials they are made of. Retinal reattachment and stability in RD cases are the necessary conditions to focus iSD-OCT on instruments‘ tips. The imaging of the instruments allows us to control the distance between their tips and the retina to avoid iatrogenic trauma.