Microscope-integrated Intraoperative Optical Coherence Tomography Research Articles

Comparing Three-Dimensional Digitally Enabled Intraoperative OCT With Conventional Microscope-Integrated OCT in Vitreoretinal Surgery: A Post Hoc Analysis of the DISCOVER Study.

This study compared the surgeon experience between conventional microscope-integrated intraoperative optical coherence tomography (iOCT) and digitally enabled microscope-integrated iOCT in vitreoretinal surgery. This is a post hoc case-control analysis of the DISCOVER study. Conventional microscope-integrated iOCT (Rescan 700, Zeiss) was compared with digitally enabled iOCT (Artevo 800, Zeiss). Compared variables included surgical field-based visualization (ie, ocular heads-up display in the conventional group; three-dimensional screen-based visualization in the digital iOCT group) and non-surgical field-based visualization (ie, review on the external two-dimensional monitor). A total of 200 patients were included. Surgical field-based visualization of iOCT was significantly higher in the digitally enabled group (P < 0.0001). Required endoillumination level was significantly lower in the digital iOCT group (P < 0.0001). Surgeons reported "significant" back discomfort and headache more frequently when using conventional iOCT (P = 0.003 and P = 0.001, respectively). Digitally enabled iOCT resulted in greater surgical visualization efficiency, appeared to require a lower illumination level, and may provide advantages for ergonomic-related discomfort. [Ophthalmic Surg Lasers Imaging Retina 2024;55:270-277.].

IOCT-guided simulated subretinal injections: a comparison between manual and robot-assisted techniques in an ex-vivo porcine model

The purpose of this study is to compare robot-assisted and manual subretinal injections in terms of successful subretinal blistering, reflux incidences and damage of the retinal pigment epithelium (RPE). Subretinal injection was simulated on 84 ex-vivo porcine eyes with half of the interventions being carried out manually and the other half by controlling a custom-built robot in a master–slave fashion. After pars plana vitrectomy (PPV), the retinal target spot was determined under a LUMERA 700 microscope with microscope-integrated intraoperative optical coherence tomography (iOCT) RESCAN 700 (Carl Zeiss Meditec, Germany). For injection, a 1 ml syringe filled with perfluorocarbon liquid (PFCL) was tipped with a 40-gauge metal cannula (Incyto Co., Ltd., South Korea). In one set of trials, the needle was attached to the robot’s end joint and maneuvered robotically to the retinal target site. In another set of trials, approaching the retina was performed manually. Intraretinal cannula-tip depth was monitored continuously via iOCT. At sufficient depth, PFCL was injected into the subretinal space. iOCT images and fundus video recordings were used to evaluate the surgical outcome. Robotic injections showed more often successful subretinal blistering (73.7% vs. 61.8%, p > 0.05) and a significantly lower incidence of reflux (23.7% vs. 58.8%, p < 0.01). Although larger tip depths were achieved in successful manual trials, RPE penetration occurred in 10.5% of robotic but in 26.5% of manual cases (p > 0.05). In conclusion, significantly less reflux incidences were achieved with the use of a robot. Furthermore, RPE penetrations occurred less and successful blistering more frequently when performing robotic surgery.

The Role of the Intraoperative Optical Coherence Tomography for Vitreoretinal Surgery in a Real-Life Setting.

To descriptively report the advantages and the feasibility of microscope-integrated intraoperative optical coherence tomography (i-OCT) in managing different vitreoretinal diseases in a real-life setting. We conducted an observational retrospective study involving 265 eyes that underwent elective retinal surgery and intraoperative OCT between 1 September 2018 and 1 October 2022 at Eyecare Clinic (Brescia, Italy). 52 epiretinal membranes, 30 retinal detachments, 60 high myopic eyes, 30 choroidal transplants, 40 macular holes, and 32 vitreo-proliferative retinopathies underwent vitreoretinal surgery and intraoperative OCT scans. The i-OCT was a useful diagnostic exam for all cases and significantly influenced our surgical management. i-OCT is a helpful surgical tool in ophthalmic surgery as it provides real-time feedback of tissue anatomy to surgeons, thereby guiding decision-making. Moreover, it provides additional information on the microarchitectural changes after instrument-tissue interactions, further guiding procedures when necessary and possibly reducing unessential surgical maneuvers.

Clinical and diagnostic imaging profile of three anterior segment dysgenesis disorders presenting with infantile corneal opacities.

To describe three anterior segment dysgenesis disorders with infantile corneal opacities, namely, congenital hereditary endothelial dystrophy (CHED), primary congenital glaucoma (PCG), and Peters anomaly (PA) in terms of clinical characteristics, histopathology, genetic association, and diagnostic imaging profiles using imaging modalities such as ultrasound biomicroscopy (UBM) and microscope-integrated intraoperative optical coherence tomography (i-OCT). Seventy-four eyes with 22 eyes of CHED, 28 eyes of PA, and 24 eyes of PCG were clinically evaluated and underwent imaging using UBM and i-OCT. Corneal buttons of 16 operated patients underwent histopathological analysis, while genetic analysis was done in 23 patients using whole-exome sequencing. Corneal diameters (CD) and UBM parameters like anterior chamber depth (ACD), iris thickness (IT), and ciliary body (CB) thickness revealed a statistically significant difference between the three categories. In PA, 9 eyes had a third rare phenotype with only a posterior corneal defect with no iris adhesions. Genetic mutations were seen in all tested patients with CHED, in 83.3% of patients with PCG, and in 80% of patients with the third type of PA. i-OCT helped in the characterization of corneal opacity, identification of posterior corneal defects, iridocorneal adhesions, and contour of Descemet's membrane. Overlapping phenotypes of the above disorders cause a diagnostic dilemma and parameters like CDs, UBM ACD, IT, and CB thickness help differentiate between them. i-OCT can help in classifying the diseases in a high resolution, non-contact manner, and can better delineate corneal characteristics. The rare third type of PA phenotype may have a genetic association.

Commentary: Scleral penetration or perforation during strabismus surgery.

Commentary: Scleral penetration or perforation during strabismus surgery.

Microscope-Integrated Intraoperative Optical Coherence Tomography-Guided Big-Bubble Deep Anterior Lamellar Keratoplasty.

The purpose of this study was to evaluate the feasibility of microscope-integrated intraoperative optical coherence tomography (OCT) for real-time quantitative analysis of surgical planes in big-bubble deep anterior lamellar keratoplasty (DALK). In this interventional case series, intraoperative OCT-guided big-bubble DALK was performed in 16 consecutive eyes of 16 patients with keratoconus. Trephination depth was measured using the intraoperative OCT caliper tool. Aiming for a depth within 150 μm from the endothelial surface, the trephination groove was extended to a deeper plane using a 15-degree blade. Repeat OCT scans were taken to measure residual stromal thickness before insertion of the DALK probe from the bottom of the extended trephination. Caliper measurements, success rate of pneumatic dissection, and complications were recorded. After trephination, residual stromal thickness exceeded 150 μm in all eyes and averaged 257.1 ± 42.5 μm. In each case, the initial trephination groove was extended to a depth within 150 μm from the endothelial surface (118.9 ± 27.1 μm). Big-bubble formation was achieved in 12 eyes (75%). Type 1 bubble was obtained in 11 eyes. Perforation requiring conversion to penetrating keratoplasty occurred in 4 eyes during insertion of the cannula into a residual stromal bed of <100 μm (n = 2; 63 and 75 μm) or layer-by-layer dissection (n = 2). Quantitative analysis of intraoperative OCT scans can be used to assist decision-making on whether to proceed with pneumatic dissection or extend the trephination groove, thereby facilitating insertion of the injection cannula at the desired stromal depth.

Submacular integration of hESC-RPE monolayer xenografts in a surgical non-human primate model

BackgroundHuman pluripotent stem cells (hPSCs) provide a promising cell source for retinal cell replacement therapy but often lack standardized cell production and live-cell shipment logistics as well as rigorous analyses of surgical procedures for cell transplantation in the delicate macula area. We have previously established a xeno- and feeder cell-free production system for hPSC differentiated retinal pigment epithelial (RPE) cells, and herein, a novel immunosuppressed non-human primate (NHP) model with a disrupted ocular immune privilege is presented for transplanting human embryonic stem cell (hESC)-derived RPE on a scaffold, and the safety and submacular graft integration are assessed. Furthermore, the feasibility of intercontinental shipment of live hESC-RPE is examined.MethodsCynomolgus monkeys were systemically immunosuppressed and implanted with a hESC-RPE monolayer on a permeable polyester-terephthalate (PET) scaffold. Microscope-integrated intraoperative optical coherence tomography (miOCT)-guided surgery, postoperative follow-up incorporated scanning laser ophthalmoscopy, spectral domain (SD-) OCT, and full-field electroretinography (ERG) were used as outcome measures. In addition, histology was performed after a 28-day follow-up.ResultsIntercontinental cell shipment, which took >30 h from the manufacturing to the transplantation site, did not alter the hESC-RPE quality. The submacular hESC-RPE xenotransplantation was performed in 11 macaques. The miOCT typically revealed foveal disruption. ERG showed amplitude and peak time preservation in cases with favorable surgical outcomes. Histology confirmed photoreceptor preservation above the grafts and in vivo phagocytosis by hESC-RPE, albeit evidence of cytoplasmic redistribution of opsin in photoreceptors and glia hypertrophy. The immunosuppression protocol efficiently suppressed retinal T cell infiltration and microglia activation.ConclusionThese results suggest both structural and functional submacular integrations of hESC-RPE xenografts. It is anticipated that surgical technique refinement will further improve the engraftment of macular cell therapeutics with significant translational relevance to improve future clinical trials.

Hints for Gentle Submacular Injection in Non-Human Primates Based on Intraoperative OCT Guidance

PurposeDelivery of Advanced Therapy Medicinal Products to the submacular space is increasingly evolving into a therapeutic modality. Cell replacement for age-related macular degeneration (AMD) and gene therapy for RPE65 are recent successful examples. Herein, a nonhuman primate (NHP) model was used to investigate surgical means to detach the macula.MethodsSixteen eyes of 13 healthy macaques underwent a 25-gauge vitrectomy and subretinal injection of balanced salt solution monitored by microscope-integrated intraoperative optical coherence tomography (miOCT). The animals were followed with OCT and histology.ResultsThe miOCT monitoring allowed a more precise definition of surgical trauma ranging from an initial full-thickness foveal tear, or induction of a cystoid macular edema (CME), until no foveal defect was discernible, as the technique improved. However, as the subretinal fluid wave detached the fovea, the aforementioned lesions formed, whereas persistent retinal adhesion reproducibly proved to remain in the distal parafoveal semi-annulus. Measures to reduce foveal trauma during submacular fluid injection included reducing intraocular pressure, injection volume, and velocity, as well as the retinal location for bleb initiation, use of a vitreous tamponade, and a dual-bore subretinal cannula.ConclusionsA stable very low intraocular pressure and careful subretinal injection may avoid tangential macular stretching or mechanical CME formation, while vitreous tamponade may facilitate a more lamellar subretinal flow, all thereby reducing foveal trauma during submacular injection in NHP.Translational RelevanceThese results can be relevant to any submacular surgery procedure used today, as they synergistically reduce the risk of compromising foveal integrity.

Role of Microscope-Intraoperative Optical Coherence Tomography in Pediatric Keratoplasty: AComparative Study

We evaluate the role of microscope-integrated intraoperative optical coherence tomography (i-OCT) in pediatric keratoplasty. Combined prospective and retrospective, comparative, interventional study conducted at the Dr Rajendra Prasad Center for Ophthalmic Sciences in New Dehli, India. Seventy-five children ≤16 years of age undergoing planned keratoplasty were divided into 2 groups and compared regarding intraoperative course and postoperative outcome. In group 1 (prospective group, n= 56), preoperative anterior segment visualization was performed clinically, with ultrasound biomicroscopy (UBM) and i-OCT and keratoplasty was commenced under i-OCT microscope. In group 2 (retrospective group, n= 19), a conventional microscope was used during keratoplasty. In group 1, i-OCT, UBM, and clinical examination detected retrocorneal membrane in 10%, 7.5%, and 5% (P= .005), iris adhesions in 62.5%, 57.5%, and 20% (P= .02), iris stump in aniridia 15%, 10%, and 0% (P= .001), shallow central anterior chamber in 22.5%, 22.5%, and 7.5% (P= .003), and shallow peripheral anterior chamber in 65%, 60%, and 17.5% (P= .004) of children, respectively. The use of i-OCT affected intraoperative surgeon decision making in 45% and 33% of cases of anterior and posterior lamellar keratoplasty, respectively. During penetrating keratoplasty, concomitant intraoperative procedures were higher in group 1 than in group 2, namely synechiolysis (19/40 vs 2/15; P= .1), pupilloplasty (4/40 vs 0/15; P= .02), lens extraction (4/40 vs 1/15; P= .5), and anterior vitrectomy (2/40 vs 1/15; P= .4). Postoperative secondary interventions were lower (P= .04) in group 1 (48.21% vs 94.74%). Anterior segment imaging with i-OCT and UBM immediately before surgery improves the surgical planning of children with corneal opacities. In addition, the use of i-OCT refines intraoperative steps, thereby optimizing the postoperative outcome of pediatric keratoplasty.

Observation of Gonio Structures during Microhook Ab Interno Trabeculotomy Using a Novel Digital Microscope with Integrated Intraoperative Optical Coherence Tomography.

Purpose Observation of ocular structures using microscope-integrated intraoperative optical coherence tomography (iOCT) has been adopted. Using the novel digital ophthalmic microscope, ARTEVO 800 with iOCT, we tested the feasibility of trabecular meshwork (TM) imaging during microhook ab interno trabeculotomy, a minimally invasive glaucoma surgery. Methods The nasal and temporal sides of the TM/inner wall of Schlemm's canal were incised more than 3 clock hours in 14 glaucomatous eyes of 10 patients. To observe the trabeculotomy site, iOCT was performed with the real-time five-line scan mode under observation using a Swan-Jacob gonioprism lens. The success of the imaging and visibility of the trabeculotomy cleft and its incisional patterns (i.e., anterior, middle, or posterior pattern) were determined by reviewing the iOCT video files. Results OCT images of the region of interest were acquired successfully in 100% of the 28 nasal or temporal sides in 14 eyes, although the trabeculotomy cleft was not visualized in four (14%) sides due to blockage of the OCT signal by a blood clot. Based on the predominant locations of the TM flaps in 24 of the acquired images, the trabeculotomy clefts were classified as anterior incisional patterns in 13 (54%), middle incisional patterns in nine (38%), and posterior incisional patterns in two (8%). Conclusion Intraoperative imaging of the gonio structures including the trabeculotomy cleft was feasible using the ARTEVO 800 with iOCT in combination with a gonioprism.

Microscope-integrated Intraoperative Optical Coherence Tomography for Anterior Segment Surgical Maneuvers.

PurposeTo evaluate the potential value of microscope-integrated optical coherence tomography (MI-OCT) in anterior segment surgical maneuvers.MethodsTwenty-four ophthalmology residents, who were randomly and evenly divided into two groups, performed four anterior segment surgical maneuvers (corneal tunnel, scleral tunnel, simple corneal suture, and corneal laceration repair) on porcine eyes with (group B) or without (group A) real-time MI-OCT feedback. All residents performed the maneuvers again without MI-OCT.ResultsCompared with group A, group B (with MI-OCT) showed better accuracy in the length/depth of the corneal tunnel and the length of the scleral tunnel. However, both groups showed similar performances in the depth of both the simple corneal suture and the corneal laceration suture. When both groups performed the maneuvers again without MI-OCT, group B still showed better results than group A for the length of both the corneal and scleral tunnels.ConclusionsPrimary results suggest that real-time MI-OCT images are valuable for some anterior segment surgical maneuvers and could be helpful in surgical training.Translational RelevanceMI-OCT systems can be valuable in improving accuracy and decision making during anterior segment surgery and will be useful in surgical training.

&lt;p&gt;Microscope Integrated Intraoperative Optical Coherence Tomography-Guided DMEK in Corneas with Poor Visualization&lt;/p&gt;

PurposeTo assess the utility of microscope-integrated intraoperative optical coherence tomography (Mi-OCT) for performing Descemet membrane endothelial keratoplasty (DMEK) in corneas with poor visualization.MethodsIt is a prospective interventional case series that included 25 consecutive cases of corneal decompensation with poor visualization that underwent Mi-OCT-guided DMEK at a tertiary eye care centre. The main outcome measures were graft attachment on day 3 and requirement for re-bubbling.ResultsThe etiology for corneal decompensation was pseudophakic bullous keratopathy (n=17), Fuchs endothelial corneal dystrophy (n=4), failed graft (n=2), iridocorneal endothelial syndrome (n=1) and failed Descemet stripping automated endothelial keratoplasty (n=1). Complete graft attachment was noted in 72% of cases. Graft detachment was noted in 16% of cases which required re-bubbling. No intervention was done for shallow peripheral detachment (n=2) and peripheral Descemet membrane (DM) fold (n=1). All grafts were attached at six-months follow-up. The mean corrected distance visual acuity and central corneal thickness improved from 1.4 ± 0.5 logMAR and 799.6 ± 110.9 µm at baseline to 0.3 ± 0.3 logMAR and 536.28 ± 11.44 um at six months. Mi-OCT was helpful in visualizing areas of peripheral anterior synechiae, missing DM, retained DM tags after descemetorhexis, DMEK roll configuration and orientation in the injector and anterior chamber, interface fluid and peripheral folds in the DMEK graft.ConclusionMi-OCT helps in identification of the anatomy and dynamics of the host DM, DM roll and anterior chamber in cases with poor visualization and is a useful tool while performing DMEK in such cases.

Anterior vitreous detachment: risk factor for intraoperative complications during phacoemulsification.

To confirm the presence of incomplete vitreolenticular adhesion via microscope-integrated intraoperative optical coherence tomography (iOCT) during cataract surgery and via diagnostic spectral-domain OCT (SD-OCT) postoperatively. S. Fyodorov Eye Microsurgery Complex State Institution, Moscow, Russia. Prospective noninterventional single-center study. Clinical characteristics and surgical videos of 27 patients (28 eyes) who had cataract surgery were documented. Real-time iOCT integrated into the surgical microscope was directed to view the retrolenticular anatomy at the end of the surgery. Postoperatively, SD-OCT was also performed. This study comprised 28 eyes of 27 patients. Berger space was identified in 21 cases (75%) intraoperatively via iOCT and in 23 cases (82%) postoperatively via stationary OCT. Depth dimensions varied from 33.5 ± 87.0 μm to 383.1 ± 226.3 μm. Hyperreflective dots and particles of different shapes and sizes were documented within Berger space in 16 cases (57%) intraoperatively and in 9 cases (32%) postoperatively. Capsular rupture occurred in 1 case due to excessive posterior capsular movement anteriorly. The posterior capsular rupture was converted into a posterior capsulorhexis, leaving the anterior hyaloid membrane intact. iOCT confirmed the penetration of crystalline lens microfragments, cellular material, or medical suspension (triamcinolone) into the space between the posterior lens capsule and the anterior hyaloid membrane. This occurs due to discontinuity of both lenticular zonules and Wieger ligament attachment. A Wieger ligament rupture can also allow excessive Berger space hydration during phacoemulsification leading to anterior displacement of the posterior lens capsule increasing the risk of instrument touch and posterior capsule rupture.

THE INTEGRATIVE SURGICAL THEATER: Combining Intraoperative Optical Coherence Tomography and 3D Digital Visualization for Vitreoretinal Surgery in the DISCOVER Study.

To evaluate the feasibility of integrating intraoperative optical coherence tomography (OCT) with a digital visualization platform for vitreoretinal surgery. The DISCOVER study is a prospective study examining microscope-integrated intraoperative OCT across multiple prototypes and platforms. For this assessment, a microscope-integrated OCT platform was combined with a three-dimensional (3D) surgical visualization system to allow for digital display of the OCT data stream on the large immersive display. Intraoperative OCT scans were obtained at various surgical milestones that were directly overlaid to the surgical view in a 55-inch passive 3D 4K high-definition display. Surgeon feedback was obtained related to system performance and integration into the surgical procedures through a prespecified surgeon questionnaire. Seven eyes of seven subjects were identified. Clinical diagnosis included epiretinal membrane (n = 3), macular hole (2), symptomatic vitreous opacity (1), and proliferative vitreoretinopathy (1). Optical coherence tomography images were successfully obtained and displayed on the 4K screen in all cases. Intraoperative OCT images facilitated identification of subtle retinal alterations. Surgeons reported that the 4K screen seemed to provide improved visualization of the OCT data stream compared with the semitransparent ocular view. Surgeons were able to examine the OCT data on the 4K screen without reverting to the external display system of the microscope. The system provided a uniform surgical visualization experience for both the surgeon and the assistant. In addition, the digital platform allowed all surgical personnel to simultaneously view both the OCT and the surgical field. All eyes underwent uneventful vitrectomy without reverting to the conventional microscope. No intraoperative adverse events occurred. Integration of OCT into the digital visualization system may enable unique opportunities for surgeon feedback of intraoperative diagnostics. The overlay of the OCT data onto the 4K monitor seemed to provide excellent visualization of OCT details. Further research is needed to compare the conventional microscope-based approach to the digital 3D screen approach in regards to intraoperative OCT.

Microscope-integrated intraoperative optical coherence tomography in examination of pediatric patients under anesthesia

The therapeutic principle of examinations of children under general anaesthesia using microscope-integrated optical coherence tomography (MI-OCT) is presented. The aim was to assess novel indications as well as limitations for MI-OCT to enhance ophthalmological examinations of neonates and children under general anesthesia. The study was based on a review of the literature from google.scholar.com and PubMed and our own data from aprospective study (Department for Ophthalmology, University of Cologne) of 14children with anterior and posterior segment anomalies undergoing examinations under anesthesia. Patients were examined using acommercially available MI-OCT device. The study analyzed the general feasibility of MI-OCT for ophthalmological examination of children under general anesthesia for the anterior and posterior eye segments and the benefits of indications and intraoperative findings. The MI-OCT significantly enriched the examinations of children under general anesthesia and delivered additional information not visible with the surgical microscope. Even in situations with alimited anterior chamber view MI-OCT enabled estimation of distances, such as corneal thickness. In addition to influencing therapeutic decisions, in 12/14children MI-OCT also enabled examination of the thickness of the nerve fibre layer of the optic nerve disc and the retina. The data presented here underline the benefit of the intraoperative MI-OCT in ophthalmological examinations of children under general anesthesia. In particular MI-OCT enables examinations of children with corneal opacification, if an ophthalmological examination under general anesthesia becomes necessary.

Intraoperative Optical Coherence Tomography (MI-OCT) for the Treatment of Corneal Dystrophies

The surgical treatment of corneal dystrophies develops rapidly as the use of lamellar corneal grafting techniques continue. While penetrating keratoplasty was the gold standard for treating a variety of dystrophies a few years ago, the affected layers of the cornea can, nowadays, be selectively replaced or ablated using laser technology. Of particular importance for these methods is optical coherence tomography, which has recently been integrated into surgical microscopes (MI-OCT). Literature overview from PubMed and Google.scholar.de supplemented with own imaging data. The MI-OCT enables the intraoperative real-time monitoring of different ophthalmic surgical procedures, such as deep anterior lamellar keratoplasty, Descemet's membrane endothelial keratoplasty, as well as minimally-invasive procedures, such as phototherapeutic keratectomy. In addition, it enables an evaluation of the cornea, but also of structures of the anterior chamber, in situations in which the cornea, for example, is clouded by an edema. Microscope-integrated, intraoperative optical coherence tomography (MI-OCT) represents a useful supplement to the normal surgical microscope. It is superior to the sole surgical microscope, especially in already severely clouded corneas, and represents a sensible supplement, especially for novel lamellar transplantation procedures. Prospective randomized trials are necessary to increase safety and efficacy when using MI-OCT for different indications.

Microscope-Integrated Intraoperative Ultrahigh-Speed Swept-Source Optical Coherence Tomography for Widefield Retinal and Anterior Segment Imaging.

To demonstrate the feasibility of retinal and anterior segment intraoperative widefield imaging using an ultrahigh-speed, swept-source optical coherence tomography (SS-OCT) surgical microscope attachment. A prototype post-objective SS-OCT using a 1,050-nm wavelength, 400 kHz A-scan rate, vertical cavity surface-emitting laser (VCSEL) light source was integrated to a commercial ophthalmic surgical microscope after the objective. Each widefield OCT data set was acquired in 3 seconds (1,000 × 1,000 A-scans, 12 × 12 mm2 for retina and 10 × 10 mm2 for anterior segment). Intraoperative SS-OCT was performed in 20 eyes of 20 patients. In six of seven membrane peels and five of seven rhegmatogenous retinal detachment repair surgeries, widefield retinal imaging enabled evaluation pre- and postoperatively. In all seven cataract cases, anterior imaging evaluated the integrity of the posterior lens capsule. Ultrahigh-speed SS-OCT enables widefield intraoperative viewing in the posterior and anterior eye. Widefield imaging visualizes ocular structures and pathology without requiring OCT realignment. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:94-102.].

Intraoperative changes in corneal structure during excimer laser phototherapeutic keratectomy (PTK) assessed by intraoperative optical coherence tomography.

Excimer laser phototherapeutic keratectomy (PTK) is a safe treatment for superficial corneal opacities, e.g., in corneal dystrophies or degenerations. Nevertheless, no standardized treatment protocols are available and intraoperative monitoring was not possible, so far. Here we evaluate the potential benefits of the intraoperative assessment by microscope-integrated intraoperative optical coherence tomography (MI-OCT) of corneal optical properties during PTK. Retrospective study of eight patients (one male, seven females; age range, 43-80years, mean = 66.1years) using an 840-nm microscope-integrated spectral-domain OCT (iOCT; OptoMedical Technologies, Luebeck, Germany adapted to HS Hi-R Neo 900A, Haag Streit Surgical, Wedel, Germany). Images were acquired before and after corneal abrasion and after PTK. For PTK, a SCHWIND Amaris 750S excimer laser (SCHWIND eye-tech-solutions GmbH und KO. KG) was used. Parameters assessed were the central corneal thickness (CCT), changes in central depth-dependent corneal tissue intensity (TI), and corneal surface roughness (SR) in cross-sectional images of the cornea. Intraoperative monitoring using microscope-integrated OCT was possible in all patients at all time points. TI of the anterior corneal stroma decreased significantly (p = 0.037) after PTK (T1 = 15.1 ± 3.6, T2 = 15.0 ± 3.84, T3 = 13.7 ± 3.38), but not after corneal abrasion alone, indicating increased transparency caused by excimer laser PTK. CCT was significantly lower after corneal abrasion (p = 0.017), but not after PTK (T1 = 630.4 ± 70μm, T2 = 544.1 ± 59.4μm, T3 = 558.3 ± 52.5μm. SR significantly decreased (p = 0.043) after PTK (T1 = 614.4 ± 37.5 pixels, T2 = 634.4 ± 35.6 pixels, T3 = 611.0 ± 40.3 pixels). Intraoperative OCT allows real-time imaging during PTK and the assessment of corneal optical transparency and its surface roughness. It has to be clarified in larger studies if these parameters correlate with later postoperative visual outcomes.

Diagnostic precision of a microscope-integrated intraoperative OCT device in patients with epiretinal membranes.

Preoperative and postoperative optical coherence tomography (OCT) of macular pathologies can be regarded as the gold standard diagnostic technique, providing detailed information on the microstructures of the macula for planning the surgical procedure and comparing improvements after surgery in the follow-up period. Intraoperative use of OCT is a novel application to support surgeons during macular surgery. The aim of this study was to examine the diagnostic precision of a microscope-integrated intraoperative spectral-domain OCT (i-OCT) device and compare imaging results to a stand-alone spectral-domain OCT (SD-OCT) device. This prospective study included 41 eyes of 41 patients scheduled for pars plana vitrectomy with membrane peeling due to an idiopathic epiretinal membrane (ERM). Intraoperative imaging with the i-OCT device was performed at the beginning of the surgery and compared to preoperative SD-OCT images. Preoperative and intraoperative SD-OCT evaluations showed high intraobserver and interobserver reproducibility for the presence of ERM, lamellar macular hole, and vitreomacular traction. For intraretinal cystoid changes, intraobserver and interobserver reproducibility for both OCTs was rather poor, mainly due to microcystic changes. Intraoperative spectral-domain OCT offers high reproducibility regarding the visibility of ERM, lamellar macular holes, and vitreomacular traction. Microcystic changes cause discrepancies in interpretation, often simply diagnosed as retinal thickening.

Microscope-integrated intraoperative optical coherence tomography-guided small-incision lenticule extraction: New surgical technique

We describe the surgical technique of microscope-integrated intraoperative optical coherence tomography (OCT)-guided small-incision lenticule extraction. The technique enables manual tracking of surgical instruments and identification of the desired dissection plane. It also helps discern the relation between the dissector and the intrastromal lenticule. The dissection plane becomes hyperreflective on dissection, ensuring complete separation of the intrastromal lenticule from the overlying andunderlying stroma. Inadvertent posterior plane entry, cap-lenticule adhesion, incomplete separation of the lenticule, creation of a false plane, and lenticule remnants may be recognized intraoperatively so corrective steps can be taken immediately. In cases with a hazy overlying cap, microscope-integrated intraoperative OCT enables localization and extraction of the lenticule. The technique is helpful for inexperienced surgeons, especially in cases with low amplitudes of refractive errors, ie, thin lenticules.