Evaluation of the Use of Intraoperative OCT in Routine Surgery: A Two-year Comparison. / Evaluation der Nutzung von intraoperativer OCT im operativen Alltag: ein 2-Jahres-Vergleich.

BACKGROUND: In recent years, an increasing number of surgical microscopes fitted with an OCT module (intraoperative OCT, iOCT) have become available, providing high-resolution images of the surgical site in real time. While a 2018 survey at our hospital showed that iOCT delivered an additional intraoperative benefit in only 2.4% of all operations, considering that the manufacturer had since revised the hardware and software, we conducted a second user evaluation of this technology. MATERIAL AND METHODS: Prospective monocentric analysis of the application and user-friendliness of an EnFocus Ultra-Deep OCT (Leica Microsystems) over a period of 25 (2018) and 20 working days (2021). A standardized questionnaire was used to assess the surgeons' use of iOCT and its influence on the surgical course. RESULTS: 118 operations were performed over a 25-day period in 2018 and 92 operations were performed over a 20-day period in 2021. In 2018, iOCT was used in 24.6% and in 2021 in 48.9% of all surgeries, with iOCT proving to be "critical" to the surgical course in 2.4% and 3.3% of cases, respectively, as assessed by the surgeons in both years. These were operations in which the intraocular view was limited, e.g., with decompensated cornea, vitreous hemorrhage, or after previous surgery, e.g., after penetrating keratoplasty. CONCLUSION: Further development of the user interface led to an improvement in usability, and the iOCT was used significantly more often. In both years, the iOCT proved to be critical for the course of the surgery in a comparably small number of operations, especially those involving complex situations.

Intraoperative OCT - Real-World User Evaluation in Routine Surgery. / Das intraoperative OCT ­ eine Real-World-basierte Nutzerevaluation im operativen Alltag.

BACKGROUND: In recent years, great progress has been made in intraoperative imaging using optical coherence tomography (iOCT). There are now several commercially available iOCT systems that allow high-resolution imaging of all structures of the eye without interrupting surgery. This real-time visualisation can provide additional information to conventional surgical microscopy, but is relatively expensive. The aim of our study was to find out how often OCT integrated into the surgical microscope is used by trained surgeons, or to what extent they consider that iOCT is relevant for intraoperative procedures. PATIENTS AND METHODS: A prospective monocentric analysis was conducted of the field of application and user-friendliness of the EnFocus Ultra-Deep OCT (Leica Microsystems), a mobile device combination of surgical microscope and OCT. The use and benefit were investigated of iOCT, which was not mandatory. Standardised documentation and evaluation using a questionnaire was performed by the respective surgeon (n = 5) immediately after surgery. RESULTS: Over a period of 25 working days, 118 procedures were performed in the operating theatre equipped with the microscope-OCT combination. The iOCT was used in 24.6% of the 118 procedures performed. iOCT was regarded as crucial to the intraoperative procedure in 3 of the 29 patients. In one patient, it was possible to check graft orientation during a DMEK operation in a very opaque cornea and, in the second patient, to visualise the correct positioning of an iris diaphragm in the capsular bag. In the third patient, the risk of developing a pseudoforamen was assessed, and this led to the decision not to perform a full gliosis peel. CONCLUSION: Experienced surgeons in a university eye hospital with a full surgical spectrum considered that intraoperative OCT was decisive for the course of surgery in only a few selected surgical situations, e.g. in case of limited corneal transparency. The impact of the use of iOCT on post-operative outcome quality still needs to be evaluated by larger prospective studies. On the basis of this survey, the cost-benefit ratio is still unclear.

A method for quantifying limbal stem cell niches using OCT imaging.

AIMS: To evaluate the efficacy of Fourier domain-optical coherence tomography (FD-OCT) in imaging and quantifying the limbal palisades of Vogt and to correlate these images with histological findings. METHODS: The superior and inferior limbal region of both eyes of 50 healthy volunteers were imaged by FD-OCT. Images were processed and analysed using Matlab software. In vitro immunofluorescent staining of a cadaveric donor limbus was analysed to correlate the presence of stem cells in the visualised structures. RESULTS: FD-OCT could successfully visualise limbal crypts and the palisades of Vogt in the limbus region. Fluorescent labelling confirmed the presence of stem cells in these structures. The mean palisade ridge width (ΔPR) and the mean interpalisade epithelial rete peg width (ΔERP) were both of the order of 72 µm, leading to a palisade density (PD) of about 7.4 palisades/mm. A significant difference in ΔPR, ΔERP and PD was seen between the inferior and superior sides of the right eye and the superior sides of the left and right eye(p<0.05.). A significant influence of iris colour on parameters ΔPR, ΔERP and PD was found, and of age on PD and ΔERP (p<0.05). CONCLUSIONS: In vivo OCT imaging is a safe and effective modality to image the limbus and can be used to visualise the palisades of Vogt. Image processing using Matlab software enabled quantification and density calculation of imaged limbal palisades of Vogt. This technique may enhance targeted limbal biopsies for transplantation.