Optische Technologien, digital unterstützt: Operationsmikroskop – quo vadis?

ZusammenfassungEine ausreichende Vergrößerung und die richtige Beleuchtung sind entscheidend für den Erfolg einer mikrochirurgischen Intervention. Operationsmikroskope sind daher aus der modernen Ophthalmochirurgie schon lange nicht mehr wegzudenken und haben sich zum Kernstück eines modernen Operationssaals entwickelt. Wir geben in diesem Beitrag zunächst eine kurze Übersicht über die historische Entwicklung ophthalmologischer Operationsmikroskope – von den ersten Entwicklungen der Mitte des 19. Jahrhunderts bis hin zum derzeitigen Stand der Technik mit leistungsfähigen Koaxialbeleuchtungen und glasfasergeführten Xenon- oder LED-Lichtquellen. Weiterhin gehen wir auf aktuelle Entwicklungen, insbesondere im Bereich der Workflowunterstützung und Integration zusätzlicher Technologien, wie intraoperative OCT oder „Augmented Reality“ bzw. dem Operateur nützliche Dateneinspiegelungen, ein. Im letzten Teil wird ein Ausblick auf künftige Entwicklungen gegeben, wobei hier vor allem die Digitalisierung der Bildkette und intelligente Assistenzautomatisierung im Vordergrund stehen.

Auswirkungen auf den vorderen Augenabschnitt beim Andocken eines Femtosekundenlasers an das Patienteninterface

Purpose. To compare the intraoperative OCT (optical coherence tomographer) of the femtosecond laser LenSx (Alcon Pharma GmbH, Freiburg) with a Scheimpflug-tomographer and an anterior segment OCT and thus to investigate a possible influence on the anterior segment of the eye when docking the patient’s interface. Material and Methods. A prospective cross-sectional study was conducted with 57 subjects who underwent a planned femtosecond laser-assisted cataract surgery or refractive lens exchange. The eye to be operated on was measured prior to the operation in mydriasis with the Visante OCT (Carl Zeiss Meditec AG, Jena) and the Pentacam AXL (Oculus Optikgeräte GmbH, Wetzlar). During the surgery, images of the anterior segment of the eye were taken by the integrated intraoperative OCT of the laser, which were evaluated afterwards and compared to the values of the other devices. The parameters examined were the internal anterior chamber depth (ACD), nasal and temporal chamber angles, central corneal thickness (CCT) and central lens thickness (LT). Results. The comparison of the intraoperative OCT and the two other devices showed clinically relevant differences in all parameters. The intraoperative OCT showed a 9.19 ± 27.55 μm larger CCT, 0.96 mm (median difference) larger LT, 0.05 mm smaller ACD than the Pentacam AXL and a 21.36 ± 25.50 μm larger CCT, 0.10 mm (median difference) smaller ACD than the Visante OCT. Conclusion. The comparison of the intraoperative OCT with the Visante OCT and the Pentacam AXL shows clinically relevant differences. Changes in the anterior segment of the eye may be due to errors in measurement or docking of the patient’s interface. Keywords. femtosecond laser, OCT, anterior segment of the eye, cataract surgery, refractive lens exchange

Capabilities of intraoperative OCT during femtoassisted phacoemulsification of cataract in congenital lens ectopia

Purpose. To prevent intraoperative complications during fixation of the IOL-intracapsular ring-capsule bag complex during femto-assisted phacoemulsification of cataract complicated by congenital lens ectopia (Marfan syndrome) using intraoperative OCT. Material and methods. 3 men (6 eyes), with a diagnosis of cataract complicated by congenital ectopia of the lens (Marfan syndrome). The age of patients ranged from 19 to 25 years. Cataract phacoemulsification (CFE) with femto support and hydrophobic IOL implantation was performed by all patients. Fixation of complex "IOL-intracapsular ring-capsule bag" in sulcus ciliaris was performed with the control of intraoperative OCT. Results. BCVA was 0.6-0.8 at the first day after the operation. According to ultrasound biomicroscopy (UBM), the IOL was in the capsule bag in a horizontal position in all cases. Any damage of the iris and ciliary body was not found. After 6 months, according to UBM, a stable horizontal position of the IOL and the consistency of suture fixation of the «intracapsular ring-capsule bag-IOL» complex was recorded in all patients. Conclusion. The use of intraoperative OCT allows to accurately determine the individual anatomical location of the sulcus ciliaris and provide visual control of the IOL suturing and the «intracapsular ring-capsule bag» complex in congenital lens tectopia, avoiding excessive trauma of the surrounding eye tissues, and also to ensure a stable horizontal position of the IOL in the postoperative period. Key words: intraoperative optical coherence tomography, femtoassisted cataract phacoemulsification, congenital lens ectopia.

Features of the formation of "Big Bubble" during deep anterior lamellar keratoplasty

Purpose. To determine the optimal channel parameters in the deep layers of the corneal stroma when performing deep anterior lamellar keratoplasty (DALK), providing the maximum frequency of air bubble formation, under the control of intraoperative optical coherence tomography. Material and methods. The study was performed at 30 patients (30 eyes) with a diagnosis of stage III keratoconus. The average age of patients is 31±7 years. All patients were divided into groups consisting of 10 patients, depending on the choice of the topographic orientation of the channel for pneumodissection in the deep layers of the corneal stroma when performing DALK: 1st group – the channel is located towards the center of the cornea; 2nd group – the channel is located paracentral to the temporal side; 3rd group – the channel is located paracentral to the nasal side. In all cases, DALK was performed with a femtosecond laser Femto LDV Z8 (Ziemer, Switzerland). The length of the formed femto channels were variable and amounted to 1.0, 1.5, 2.0, 2.5 and 3.0 mm in each group. Results. The use of intraoperative OCT demonstrated that in all 30 cases the depth of the channel for pneumodissection corresponded to preoperative calculations and amounted to 97±5µm to DM. It was found that the bedding of the channel at a distance of 100µm to the descemet membrane (DM) and its paracentral orientation is characterized by a greater frequency of formation of the «Big Bubble» in comparison with its central orientation: 3rd group – 90% and 2nd group – 80% against 1st group – 60% of cases. The study of the effect of the length of the channel for pneumodissection on the ease of formation of the "Big Bubble" demonstrated that more attempts are required to inject sterile air when channels of 2.0, 2.5, 3.0 mm being used than with short channels of 1.0, and 1, 5 mm (average 3 attempts versus 1.5 attempts, respectively). Conclusion. The paracentral orientation of the location of the channel for pneumodissection is accompanied by a higher percentage of formation of the "Big Bubble" than the central location of the channel. Manual extension of femtochannels having length of 1.0, 1.5 mm, directly with a microsurgical spatula 30G followed by inserting a metal cannula into the channel minimizes the number of attempts to inject sterile air, that facilitates the formation of the "Big Bubble". Performing DALK applying the function of intraoperative OCT allows to control the accuracy of all stages of the operation, including the stage of formation of a large air bubble. Performing DALK with the applying of the function of intraoperative OCT allows to control the accuracy of all stages of the operation, including the stage of formation of a large air bubble. Key words: deep anterior lamellar keratoplasty, Big Bubble, channel for pneumodissection

Intraoperative Optical Coherence Tomography-Guided Bleb-sparing Epithelial Exchange: A Modified Approach

With the advent of newer technologies, real-time anterior segment optical coherence tomography (OCT) integrated with the operating microscope has become possible. We are proposing the technique of bleb revision with greater precision under direct visualization of bleb anatomy and extent of tissue depth allowing better localization and easy maneuvering with lesser complications. In this surgical technique, bleb revision was performed using intraoperative real-time OCT incorporated in OPMI LUMERA 700 microscope. Live surgical and OCT view were seen on a common screen together. A moderately elevated, diffuse functional bleb was noted after three months of bleb revision in both cases with controlled intraocular pressure. Intraoperative OCT-guided bleb-sparing epithelial exchange is an adjunctive technique for bleb repair surgery with an increased precision of surgery which can reduce complications, minimize surgical time and maximize surgical outcome.

Intraoperative OCT – Real-World User Evaluation in Routine Surgery

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.