Association between transient interface fluid on intraoperative OCT and textural interface opacity after DSAEK surgery in the PIONEER study

Corneal transplantation: A walk to vision

Corneal diseases are a major cause of blindness in the world. Corneal transplantation has been a cornerstone in the management of several of these advanced pathologies. This article discusses the evolution of corneal transplantation over a century, its indications, complications and briefly the various surgical techniques. Such tremendous technical improvisations from total corneal transplantation to lamellar keratoplasties have generated significant interest in the ophthalmic world and garnered momentum to the fight against blindness. Armed Forces Medical Services are also in vogue more than ever in this forward surge.

Intraoperative OCT for Lamellar Corneal Surgery: A User Guide

Intraoperative OCT is an innovative and promising technology which allows anterior and posterior segment ocular surgeons to obtain a near-histologic cross-sectional and tomographic image of the tissues. Intraoperative OCT has several applications in ocular surgery which are particularly interesting in the context of corneal transplantation. Indeed, iOCT images provide a direct and meticulous visualization of the anatomy, which could guide surgical decisions. In particular, during both big-bubble and manual DALK, the visualization of the relationship between the corneal layers and instruments allows the surgeon to obtain a more desirable depth of the trephination, thus achieving more type 1 bubbles, better regularity of the plane, and a reduced risk of DM perforation. During EK procedures, iOCT supplies information about proper descemetorhexis, graft orientation, and interface quality in order to optimize the postoperative adhesion and reduce the need for re-bubbling. Finally, mushroom PK, a challenging technique for many surgeons, can be aided through the use of iOCT since it guides the correct apposition of the lamellae and their centration. The technology of iOCT is still evolving: a larger field of view could allow for the visualization of all surgical fields, and automated tracking and iOCT autofocusing guarantee the continued centration of the image.

Treatment of Descemet's membrane detachment after primary Descemet's stripping automated endothelial keratoplasty during surgery using intraoperative optical coherence tomography

Purpose

To present a novel microscope-integrated optical coherence tomography (iOCT)-guided surgical technique wherein Descemet's membrane detachment (DMD), occurring during vitrectomy, was treated intraoperatively in a patient who had previously undergone Descemet's stripping automated endothelial keratoplasty (DSAEK).

Observations

The surgical technique was performed on a 75-year-old man with a history of DSAEK to intraoperatively treat DMD, which occurred during vitrectomy in the left eye. A fine needle mounted on a syringe was inserted into the supra-Descemet's space under iOCT guidance. The location of the needle was easily identified by its high reflection. The interface fluid was safely aspirated under excellent visualization of the needle tip and the interface. Successful aspiration of the interface fluid was confirmed via iOCT imaging at the end of the surgery. The graft has remained well attached to the cornea throughout the one-year postoperative follow-up.

Conclusion and importance

iOCT-guided surgical interventions provide a safe and accurate approach for treating intraoperative complications in eyes with a history of DSAEK.

The Next Steps in Ocular Imaging in Uveitis

PURPOSE

To describe the future steps and advances in the field of ocular imaging in uveitis.

METHODS

Narrative review.

RESULTS

There have been numerous advances in the field of imaging in uveitis in the past decade. Advanced techniques of imaging of the vitreous, vitreo-retinal interface, retinochoroid, and the sclera can provide significant information that helps in understanding the disease pathogenesis and manifestations. Imaging also helps in establishing a diagnosis in challenging cases, along with the laboratory and other assays. Notable developments in ocular imaging include wide-field and ultra-wide field imaging (including angiographies), automated quantification of the retinochoroidal vasculature using optical coherence tomography (OCT) and OCT angiography, quantification of vitreous cells, and intraoperative use of imaging in uveitis, among others.

CONCLUSIONS

We have summarized several technological achievements in ocular imaging in the field of uveitis and provided insights into the potential future developments.

Application of Intraoperative Optical Coherence Tomography Technology in Anterior Segment Surgery

The use of optical coherence tomography (OCT) technology in anterior segment diseases allows for precise assessment of the changes following anterior segment surgery. Advances in microscope-integrated OCT systems have allowed the utilization of intraoperative OCT (iOCT) in anterior segment surgeries, i.e., cornea, cataract, and refractive surgery. iOCT has enabled real-time precise visualization of anterior segment tissues as well as interactions between surgical instruments and ocular tissue; thus, the device can facilitate surgical procedures and provide valuable information for decision-making during anterior segment surgeries. In this review, the authors will introduce studies regarding the development of iOCT technology and its application in various anterior segment surgeries. Multiple studies have shown the efficacy of the iOCT for intraoperative assistance and guidance, suggesting the potential of the device for optimizing the surgical outcomes after cornea, cataract, and refractive surgery.

An Overview of Intraoperative OCT-Assisted Lamellar Corneal Transplants: A Game Changer?

Intraoperative optical coherence tomography (iOCT) is a noninvasive imaging technique that gives real-time dynamic feedback on surgical procedures. iOCT was first employed in vitreoretinal surgery, but successively served as a guidance in several anterior segment surgical approaches: keratoplasty, implantable Collamer lens (ICL) implantation, and cataract surgery. Among all of those approaches, the unbeatable features of iOCT are fully exploited in anterior and posterior lamellar keratoplasty, and the purpose of this review is to focus on the advantages and shortfalls of iOCT in these techniques, in order to assess whether this technology could be a real step forward. In deep anterior lamellar keratoplasty (DALK), iOCT is useful to evaluate the needle depth into the corneal stroma, the big bubble dissection plane, and residual stromal bed, thus aiding the standardization of the technique and the reduction of failures. In Descemet stripping automated endothelial keratoplasty (DSAEK), iOCT allowed for clear visibility of fluid at the graft/host interface, allowing for immediate rescue maneuvers and granting the best graft apposition. In Descemet membrane endothelial keratoplasty (DMEK), iOCT can track the lenticule unfolding in real time and assess graft orientation even in severe hazy corneas, thus optimizing surgical times, as well as avoiding the use of potentially hazardous exterior markers (such as the “S” stamp) and preventing unnecessary manipulation of the graft. Overall, the role of iOCT appeared crucial in several complicated cases, overcoming the difficulties of poor visualization in a fast, non-invasive way, thus raising this approach as possible gold standard for challenging conditions. Further improvements in the technology may enable autonomous centering and tracking, overcoming the current constraint of instrument-induced shadowing.

Intraoperative optical coherence tomography-guided nanothin Descemet stripping automated endothelial keratoplasty in a patient with a remarkably thickened cornea

Purpose

To report use of intraoperative optical coherence tomography (OCT) for nanothin Descemet stripping automated endothelial keratoplasty (DSAEK) in a patient with an extremely thickened cornea due to advanced bullous keratopathy.

Observations

A 90-year-old woman with a history of multiple trabeculectomies was referred to us for treatment of advanced bullous keratopathy (1400 μm central corneal thickness). Nanothin DSAEK was planned and performed. In brief, after the removal of the loose corneal epithelium, the anterior chamber was meticulously observed using a surgical microscope and oblique light via an endoillumination probe; however, the visibility of the anterior chamber was limited because of severe corneal edema. Subsequently, a nanothin (47 μm) DSAEK graft stained with trypan blue was inserted into the anterior chamber using an NS endoinserter. Intraoperative OCT was used successfully to visualize the graft unfolding, air tamponade, and graft attachment. At 3 months postoperatively, significant corneal clearing (625 μm central corneal thickness), improvement of visual acuity (decimal 0.04), and pain relief were obtained.

Conclusions and importance

Intraoperative OCT is useful for nanothin DSAEK even when the surgical microscope view is compromised by a remarkably thickened host cornea due to advanced bullous keratopathy. As an alternative to a penetrating keratoplasty, less invasive nanothin DSAEK was successfully performed.

Clinical applications for intraoperative optical coherence tomography: a systematic review

In this systematic review, we provide an overview of the current state of intraoperative optical coherence tomography (iOCT). As iOCT technology is increasingly utilized, its current clinical applications and potential uses warrant attention. Here, we categorize the findings of various studies by their respective fields, including the use of iOCT in vitreoretinal surgery, corneal surgery, glaucoma surgery, cataract surgery, and pediatric ophthalmology. The trend observed in recent decades towards performing minimally invasive ophthalmic surgery has caused practitioners to recognize the limitations of using a conventional surgical microscope for intraoperative visualization. Thus, the superior visualization provided by iOCT can improve the safety of these surgical techniques and promote the development of new minimally invasive ophthalmic surgeries. Landmark prospective studies found that iOCT can significantly affect surgical decision making and can cause a subsequent change in surgical strategy, and the use of iOCT has potential to improve surgical outcome. Despite these advantages, however, iOCT is still a relatively new technique, and beginning users of iOCT can encounter limitations that can preclude their reaching the full potential of iOCT and in this respect several improvements are needed.

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.

Intraoperative optical coherence tomography guided corneal sweeping for removal of remnant Interface fluid during ultra-thin Descemet stripping automated endothelial keratoplasty

BACKGROUND

Remnant interface fluid following Descemet stripping automated endothelial keratoplasty (DSAEK) is associated with postoperative detachments. The aim of this study was to assess outcomes of intraoperative optical coherence tomography (iOCT) guided meticulous peripheral corneal sweeping for removal of interface fluid during ultra-thin (UT) DSAEK.

METHODS

This retrospective study included all eyes underwent iOCT guided UT-DSAEK from October 2016 to February 2018 at the Hanusch Hospital, Vienna, Austria. Peripheral meticulous corneal sweeping was performed to remove excess fluid. Central graft thickness (CGT) was measured prior to surgery, after graft bubbling and after corneal sweeping. Remnant interface fluid rates were compared between eyes that underwent rebubbling and those that did not.

RESULTS

Overall, 28 eyes of 28 patients with a mean age of 73.9 ± 10.0 years were included. An iOCT guided meticulous peripheral sweeping was performed in 89.3% (n = 25) of the cases. Following 84% (n = 21) of the peripheral sweeping performed, remnant fluid was no longer identified. Following peripheral sweeping the interface fluid height was reduced from 17.31 ± 15.96 μm to 3.46 ± 9.52 μm (p < 0.001) and CGT was reduced by 7% (p < 0.001). Rebubbling was performed in 17.9% (n = 5) of the cases. The rebubbling group had a greater proportion of patients that had remnant fluid identified with iOCT at the end of surgery despite meticulous peripheral sweeping (60.0% versus 4.4%, p = 0.01).

CONCLUSION

The iOCT identified subclinical remnant fluid in nearly 90% of UT-DSAEK cases. An iOCT guided peripheral corneal sweeping led to resolution of interface fluid in a majority of cases. Eyes with persistent remnant fluid despite peripheral corneal sweeping are more likely to require subsequent rebubbling.

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

PURPOSE

We evaluate the role of microscope-integrated intraoperative optical coherence tomography (i-OCT) in pediatric keratoplasty.

DESIGN

Combined prospective and retrospective, comparative, interventional study conducted at the Dr Rajendra Prasad Center for Ophthalmic Sciences in New Dehli, India.

METHODS

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.

RESULTS

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%).

CONCLUSIONS

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.

Intraoperative Optical Coherence Tomography: Game-Changing Technology

ABSTRACT

Intraoperative optical coherence tomography (OCT) has the potential to revolutionize lamellar corneal surgery and facilitate many other types of ocular surgery because it readily visualizes ocular structures that can be difficult to discern with a coaxial microscope, particularly through a cloudy cornea. Systems that can provide a high-quality image on demand in the surgeon's oculars, rather than just on an adjacent monitor, are the most useful because they allow the surgeon to rely on the OCT image while operating, without having to look away from the surgical field. Useful applications in lamellar corneal surgery include assessing graft attachment with Descemet stripping endothelial keratoplasty and discerning graft orientation with Descemet membrane endothelial keratoplasty, which otherwise could be challenging in an eye with a cloudy cornea. Intraoperative OCT is particularly helpful when performing deep anterior lamellar keratoplasty in cases in which a big bubble should not be attempted or cannot be achieved because it enables better intraoperative control of the incision depth and allows the surgeon to assess the uniformity of the dissection plane to optimize visual outcomes. Intraoperative OCT is also useful when judging the depth of a scar for a lamellar dissection, when evaluating intraocular lens positioning in the capsular bag, or when locating and removing retained nuclear fragments from an eye with a poor view because of a cloudy cornea. The primary barrier to the adoption of this valuable technology is cost.

Late Spontaneous Reabsorption of Interface Fluid after Descemet's Stripping Automated Endothelial Keratoplasty Surgery

An 80-year-old male was referred to our hospital for chronic bullous keratopathy in the right eye. Ten years before, he was affected by an attack of primary acute angle closure glaucoma in high hyperopia and Fuchs' endothelial dystrophy. A bilateral iridotomy was performed. Thereafter, the patient developed an endothelial decompensation in the left eye, and, in another hospital, he underwent an open-sky combined cataract extraction and penetrating keratoplasty. Our surgical approach for the right eye consisted of phacoemulsification and, after 1 month, a Descemet's stripping automated endothelial keratoplasty (DSAEK). After the procedure, an interface fluid was suspected, and an anterior segment optical coherence tomography (OCT) confirmed it. The graft was well centered but thickened, showing no movement in the anterior chamber, adherent to the periphery of the recipient cornea but with a pool of fluid in the center. Seven days postoperatively, an anterior segment OCT showed initial signs of reabsorption of the fluid. On day 45, the graft was adherent with normal thickness and the interface fluid had completely disappeared. The corneal stroma was clear, but a faint interface opacity appeared and is still present. We obtained a good surgical result and best corrected visual acuity was 7/10 at postoperative month 4. No further surgical procedures are scheduled.

Intraoperative Optical Coherence Tomography Imaging in Corneal Surgery: A Literature Review and Proposal of Novel Applications

Intraoperative optical coherence tomography (iOCT) is widely used in ophthalmic surgeries for cross-sectional imaging of ocular tissues. The greatest advantage of iOCT is its adjunct diagnostic efficacy, which facilitates to decision-making during surgery. Since the development of microscopic-integrated iOCT (MIOCT), it has been widely used mainly for vitreoretinal and anterior segment surgeries. In corneal transplantation, MIOCT allows surgeons to visualise structure underneath the turbid and distorted cornea, which are impossible to visualise with a usual microscope. Real-time visualisation of hard-to-see area reduces the operation time and leads to favorable surgical outcomes. The use of MIOCT is advantageous for a variety of corneal surgical procedures. Here, we have reviewed articles focusing on the utility of iOCT  and MIOCT in penetrating keratoplasty, deep anterior lamellar keratoplasty, Descemet stripping automated endothelial keratoplasty, and Descemet membrane endothelial keratoplasty. The applications of MIOCT to corneal surgery in terms of surgical education for trainees, emergency surgery, and novel surgery are also discussed, with our cases performed using RESCAN^® 700.

Intraoperative optical coherence tomography in anterior segment surgery

Intraoperative optical coherence tomography (iOCT) enables real-time visualization of ocular structures during surgery and enhances our understanding of intraoperative dynamics. iOCT aids in decision-making during various anterior segment surgeries, and its efficacy and feasibility in anterior lamellar keratoplasty and endothelial keratoplasty is well established. The landmark DISCOVER study observed that iOCT altered the surgeon decision in 38% of cases undergoing lamellar keratoplasty and provided guidance regarding the need for secondary surgical intervention. iOCT also finds an application in phacoemulsification wherein it helps to assess corneal incisions, intralenticular pressure, and posterior capsule integrity during nuclear emulsification. iOCT aids in the visualization of angle structures during placement of tubes and shunts in glaucoma surgeries and allows precise creation of partial thickness scleral flaps. In addition, iOCT helps in establishing a diagnosis, as well as provide intraoperative guidance, in pediatric patients who are not cooperative for examination. The role of iOCT in refractive surgeries and ocular surface disorders is increasingly being evaluated. The limitations of present-day iOCT systems are related to instrument compatibility, automated tracking of the surgical field, and on-table volumetric analysis of the real-time images. Technological advances may facilitate complete integration of OCT in the surgical microscopes for all surgical procedures.

Indications for intraoperative anterior segment optical coherence tomography in corneal surgery

PURPOSE

Recently, intraoperative optical coherence tomography (iOCT) has evolved in the field of ophthalmic surgery. So far, the use of iOCT was mainly focused to lamellar keratoplasty, especially deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). The aim of this study was to report our experiences with iOCT to introduce new possibilities of this application.

METHODS

We used iOCT in 18 patients who underwent the following surgeries: DALK, DMEK, penetrating keratoplasty, autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens, pannus removal on corneal surface and newborn investigation in Peters' anomaly. We obtained qualitative video data for all procedures.

RESULTS

With the iOCT, the cannula placement during DALK preparation of the recipient cornea and bubble formation could be visualized to improve the success rate of the big bubble injection. In DMEK, the iOCT enables the visualization of Descemet's membrane removal in the recipient and graft orientation as well as better control of graft attachment. The iOCT enables intraoperative visualization of the graft-host interface during penetrating keratoplasty. During autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens and removal of corneal surface pannus the iOCT is capable of showing the thickness of lamellar preparations to avoid penetrations and to save healthy recipient's tissue.

CONCLUSION

The iOCT is a helpful device for intraoperative anterior segment imaging not only for DALK and DMEK. It is also beneficial in penetrating keratoplasty and every other form of lamellar preparation during corneoscleral surgery.

Surgical management of post-Descemet stripping automated endothelial keratoplasty interface haze associated with interface deposits

We describe an effective technique for the management of graft–host interface haze associated with interface deposits after Descemet-stripping automated endothelial keratoplasty (DSAEK) with bimanual irrigation/aspiration. A Tan marginal dissector was used to separate the graft from the stroma in the nasal two-thirds of the graft–host interface. The aspiration handpiece was inserted in the interface through the nasal side-port corneal incision and a separate irrigation tip was placed in the anterior chamber (AC) through the temporal corneal paracentesis. Meticulous rinsing of the two-thirds of the interface area and the AC was performed. At the end of the procedure, air was injected into the AC to float the donor graft against the host stromal bed and facilitate graft adherence. Postoperative anterior segment optical coherence tomography and slit-lamp examination confirmed elimination of the interface haze–deposits and a well-attached graft. An improvement in visual acuity was noted.

Intra-operative optical coherence tomography in glaucoma surgery-a systematic review

The application of the OCT in clinical ophthalmology has expanded significantly since its introduction more than 20 years ago. There has been recent growing interest in the application of intra-operative optical coherence tomography (iOCT). The iOCT's ability to enhance visualisation and depth appreciation has the potential to be further exploited in glaucoma surgery, especially with the emergence of Minimally Invasive Glaucoma Surgery (MIGS)-to facilitate targeted device placement and fine surgical manoeuvres in the angles, the sub-conjunctival layer and the suprachoroidal space. Hence, this study aims to appraise the current literature on the applications of iOCT in glaucoma surgery. A total of 79 studies were identified following a literature search adhering to PRISMA guidelines. After full text evaluation, 10 studies discussing iOCT use in glaucoma surgery were included. Traditional glaucoma filtering procedures reviewed included trabeculectomy surgery, goniosynechiolysis, bleb needling and glaucoma drainage device implantation. MIGS procedures reviewed included canaloplasty, trabecular aspiration, ab-interno trabectome and the XEN45 gel stent. iOCT use in ophthalmic surgery is becoming increasingly prevalent and has already been applied in various surgeries and procedures in the field of glaucoma. With the greater adoption of MIGS, iOCT may further contribute in facilitating surgical techniques and improving outcomes. While iOCT offers many advantages, there are still limitations to be overcome-iOCT technology continues to evolve to optimise imaging quality and user-experience.

Corneal transplantation in the modern era

Corneal blindness is one of the major causes of reversible blindness, which can be managed with transplantation of a healthy donor cornea. It is the most successful organ transplantation in the human body as cornea is devoid of vasculature, minimizing the risk of graft rejection. The first successful transplant was performed by Zirm, and since then, corneal transplantation has seen significant evolution. It has been possible because of the relentless efforts by researchers and the increase in knowledge about corneal anatomy, improvement in instruments and advancements in technology. Keratoplasty has come a long way since the initial surgeries wherein the whole cornea was replaced to the present day where only the selective diseased layer can be replaced. These newer procedures maintain structural integrity and avoid catastrophic complications associated with open globe surgery. Corneal transplantation procedures are broadly classified as full-thickness penetrating keratoplasty and partial lamellar corneal surgeries which include anterior lamellar keratoplasty [sperficial anterior lamellar keratoplasty (SALK), automated lamellar therapeutic keratoplasty (ALTK) and deep anterior lamellar keratoplasty (DALK)] and posterior lamellar keratoplasty [Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK)] broadly.

Automated 2D-3D quantitative analysis of corneal graft detachment post DSAEK based on AS-OCT images

BACKGROUND AND OBJECTIVE

In current ophthalmological practices, assessment of graft condition post Descemet's stripping automated endothelial keratoplasty (DSAEK) is performed qualitatively using few (four) anterior-segment optical coherence tomography (AS-OCT) radial B-scans. From those scans, clinicians need to mentally synthesize the graft in 3D, and estimate its overall condition. In contrast, quantitative representation of 360° thickness profile would facilitate better visualization of graft condition, and hence medical decision making. Consequently, clinicians seek to quantify potential detachments in 3D from the aforementioned sparse B-scans. Against this backdrop, aiming to assist doctors in making an accurate postoperative assessment, we attempted at 3D visualization and quantification of donor lenticule separation (DLS) using only four AS-OCT radial B-scans.

METHODS

We developed an automated methodology to model and quantify DLS in 3D using only four AS-OCT B-scans. Firstly, we demonstrated that detachment can be viewed as a tubular vessel-like structure and hence can be detected using Hessian matrix analysis. Secondly, a two-stage interpolation was employed for determining the 3D profile of the detachment. Finally, various clinically significant parameters including type of separation (communicative and non-communicative), volume and 360° thickness profile of the detachment, thickness (central and peripheral) of the recipient cornea and donor graft were also obtained. Accuracy of the proposed algorithm was substantiated via thorough statistical analysis, specifically, vis-á-vis intra- and inter-observer repeatability using Dice coefficient (DC).

RESULTS

On twenty seven eyes of 27 patients (male and female), four radial OCT B-scans with 45° angular separation taken per eye, proposed algorithm found that donor graft detached completely in 3 eyes and detached one side (communicative) in remaining 24 eyes which is in agreement with expert's opinion. Quantitatively, proposed algorithm achieves a mean DC of 81.35% with manual reference which is close to the corresponding inter-observer repeatability value of 86.77%. Volume estimation of the detachment indicates that 11 eyes had 0-25%, 9 had 25-50%, 5 had 50-75% and 2 had 75-100% detachment.

CONCLUSIONS

Accuracy of the proposed methodology was corroborated vis-à-vis observer delineation. This model of image analysis may aid in prognostication of graft outcome in patients with graft detachment after DSAEK.

Intraoperative OCT Features and Postoperative Ellipsoid Mapping in Primary Macula-Involving Retinal Detachments from the PIONEER Study

PURPOSE

Intraoperative OCT (iOCT) has enabled visualization of subtle structural details during surgical interventions, including retinal detachment repair. The purpose of this study was to evaluate iOCT findings during retinal detachment repair and to assess their impact on anatomic and functional outcomes, including outer retinal integrity.

DESIGN

The PIONEER Intraoperative and Perioperative OCT Study is a prospective cohort, institutional review board-approved study.

PARTICIPANTS

Participants in the PIONEER undergoing surgical repair for primary macula-involving retinal detachment.

METHODS

This was a post hoc analysis of all eyes in the PIONEER undergoing surgical repair with primary macula-involving retinal detachments. Inclusion criteria included iOCT after perfluorocarbon liquid (PFO) placement, visualization of the foveal center on iOCT, and images of sufficient quality for quantitative assessment of submacular fluid volume. Exclusion criteria included recurrent retinal detachment, proliferative vitreoretinopathy, and a lack of postoperative OCT data after gas bubble resolution. Subretinal fluid volume on iOCT imaging was quantified. Qualitative review of iOCT images was performed for visualization of outer retinal bands, fluid, and retinal corrugations. Postoperative OCT images were analyzed using an ellipsoid zone (EZ) mapping platform to evaluate and quantify outer retinal metrics. Postoperative OCT images also were reviewed qualitatively for persistent subretinal fluid. Associations between various anatomic and functional outcomes were assessed.

MAIN OUTCOME MEASURES

Presence of intraoperative subretinal fluid under PFO tamponade, postoperative persistent subretinal fluid, postoperative visual acuity at 1 year, and EZ integrity at 1 year.

RESULTS

Fifteen eyes of 15 patients were analyzed. All 15 eyes (100%) showed subretinal fluid on iOCT. All eyes demonstrated spontaneous fluid resolution on follow-up OCT imaging. Increased intraoperative subretinal fluid volume under PFO tamponade trended toward significantly worse visual acuity outcome (P = 0.07). Postoperative quantitative EZ integrity at 12 months directly correlated with visual outcome (P = 0.01).

CONCLUSIONS

Intraoperative subretinal fluid persists under PFO tamponade with high frequency in eyes undergoing retinal detachment repair, but this fluid does not seem to be associated with persistent postoperative subretinal fluid. Postoperative EZ integrity is associated with visual acuity outcome, and intraoperative subretinal fluid volume under PFO tamponade also may be linked to visual outcomes.

Intraoperative OCT for Uveitis-Related Vitreoretinal Surgery in the DISCOVER Study

PURPOSE

To evaluate the feasibility and usefulness of intraoperative OCT (iOCT) for uveitis-related vitreoretinal surgeries.

DESIGN

Prospective consecutive case series.

PARTICIPANTS

Seventy-three consecutive patients (74 eyes) with a uveitis-related diagnosis.

METHODS

Eyes undergoing surgery for a uveitis-related diagnosis in the prospective Determination of Feasibility of Intraoperative Spectral Domain Microscope Combined/Integrated OCT Visualization During En Face Retinal and Ophthalmic Surgery (DISCOVER) iOCT study. Intraoperative OCT was performed at various surgical milestones. Clinical details and evaluation of the role of iOCT were assessed. A standardized surgeon survey was completed to evaluate the usefulness of iOCT during surgery.

MAIN OUTCOME MEASURES

Percentage of patients in whom iOCT provided valuable feedback and altered surgical decision making.

RESULTS

Seventy-four consecutive eyes with a uveitis-related diagnosis were enrolled in the DISCOVER study. Successful imaging was obtained in 72 of 73 eyes (98.6%). Intraoperative OCT provided valuable feedback for fluocinolone acetonide implant placement in 11 of 13 eyes (84.6%), for chorioretinal biopsies in 13 of 16 eyes (81.2%), and for retinal detachment (RD) repairs in 20 of 27 eyes (74.1%). In subretinal and chorioretinal biopsies, iOCT altered surgical decision making in 38% of patients. In uveitis-related RD repairs, iOCT resulted in alterations in the surgical procedure in 48% of patients, predominantly related to additional membrane peeling.

CONCLUSION

Intraoperative OCT during uveitis-related vitreoretinal surgery seems to provide valuable additional information that can impact surgical decision making and may enhance outcomes.

The DISCOVER Study 3-Year Results: Feasibility and Usefulness of Microscope-Integrated Intraoperative OCT during Ophthalmic Surgery

PURPOSE

To report the 3-year assessment of feasibility and usefulness of microscope-integrated intraoperative OCT (iOCT) during ophthalmic surgery.

DESIGN

Prospective, consecutive case series.

PARTICIPANTS

Adult participants undergoing incisional ophthalmic surgery with iOCT imaging who consented to be enrolled in the Determination of Feasibility of Intraoperative Spectral-Domain Microscope Combined/Integrated OCT Visualization during En Face Retinal and Ophthalmic Surgery (DISCOVER) study.

METHODS

The DISCOVER study is a single-site, multisurgeon, institutional review board-approved investigational device prospective study. Participants included patients undergoing anterior or posterior segment surgery who underwent iOCT imaging with 1 of 3 prototype microscope-integrated iOCT systems (i.e., Zeiss Rescan 700, Leica EnFocus, or Cole Eye iOCT systems). Clinical characteristics were documented, iOCT was directed by the operating surgeon at predetermined surgical time points, and each surgeon completed a questionnaire after surgery to evaluate the usefulness of iOCT during surgery.

MAIN OUTCOME MEASURES

Feasibility of iOCT based ability to obtain an OCT image during surgery and usefulness of iOCT based on surgeon reporting during surgery.

RESULTS

Eight hundred thirty-seven eyes (244 anterior segment cases and 593 posterior segment cases) were enrolled in the DISCOVER study. Intraoperative OCT demonstrated feasibility with successful image acquisition in 820 eyes (98.0%; 95% confidence interval [CI], 96.8%-98.8%). In 106 anterior segment cases (43.4%; 95% CI, 37.1%-49.9%), the surgeons indicated that the iOCT information impacted their surgical decision making and altered the procedure. In posterior segment procedures, surgeons reported that iOCT enabled altered surgical decision making during the procedure in 173 cases (29.2%; 95% CI, 25.5%-33.0%).

CONCLUSIONS

The DISCOVER iOCT study demonstrated both generalized feasibility and usefulness based on the surgeon-reported impact on surgical decision making. This large-scale study confirmed similar findings from other studies on the potential value and impact of iOCT on ophthalmic surgery.

Intraoperative OCT-assisted Surgery for Proliferative Diabetic Retinopathy in the DISCOVER Study

Purpose

To delineate the feasibility and role of intraoperative optical coherence tomography (iOCT) in surgical decision-making during vitreoretinal surgical interventions for proliferative diabetic retinopathy (PDR).

Design

Prospective, single-site, multi-surgeon consecutive case series.

Participants

Patients enrolled in the DISCOVER study who underwent vitreoretinal surgery for sequelae of PDR.

Methods

Subjects were identified from the first 2 years of the DISCOVER study that underwent vitreoretinal surgery for complications of PDR. Intraoperative imaging with a microscope-integrated iOCT system was performed at surgical milestones as determined by the surgeon. Data collected included clinical characteristics, image features, and survey-based surgeon feedback.

Main Outcome Measures

Main outcomes were 1) the percentage of cases with successful acquisition of iOCT (feasibility) and 2) the percentage of cases in which iOCT altered surgical decision-making (utility).

Results

Eighty-one eyes with PDR underwent vitreoretinal surgery in the DISCOVER study. Successful iOCT imaging was obtained for 80 of 81 eyes (98.8%). Of these, 36 (44.4%) were female and 44 (54.3%) were male. The surgeon preferred real-time feedback in 47 cases (58.6%), static review in 29 cases (36.3%), and was indeterminate in 4 cases (5%). Surgeons reported that in 2 cases (2.5%) the iOCT interfered with the surgery (e.g., microscope malfunction). In 41 of the 81 cases (50.6%), surgeons reported that iOCT provided valuable information (e.g., identification of dissection planes, identification of retinal hole). In addition, the iOCT data provided information that specifically altered the surgeon's decision making (e.g., determination of peel completion, choice of tamponade) in 21 of 81 cases (26%). No adverse events were attributed to the iOCT system.

Conclusions

The results suggest that iOCT is feasible during complex vitreoretinal surgeries in patients with PDR using a microscope-integrated OCT platform. Utilizing intraoperative OCT, appears to frequently offer key information that may impact surgical decision-making and potentially patient outcomes.

The role of intraoperative optical coherence tomography in pediatric hyphema: a case report

PURPOSE

Intraoperative optical coherence tomography (iOCT) is a valuable tool during vitreoretinal surgery, helping the decision-making process. It is particularly useful in pediatric cases to evaluate the macular anatomy intraoperatively, avoiding further potentially dangerous surgery in children. The aim of this report is to describe the role of integrated iOCT in the management of traumatic hyphema in a pediatric patient.

CASE REPORT

A 5-year-old girl was referred to our department with a history of recent domestic trauma in her right eye. Massive bleeding in the anterior chamber without visualization of the posterior segment was evident. Surgery was planned for the next day under general anesthesia. A 25-G irrigation cannula and 25-G vitrectome were inserted at the limbus into the anterior chamber for removal of the anterior chamber clot. Careful inspection of the posterior pole and retinal periphery to exclude pathologic findings was carried out. A real-time OCT integrated system was used to assess the macular anatomy and the corneal state. The postoperative course was uneventful and full visual recovery was achieved.

CONCLUSIONS

The objective confirmation of macular integrity by means of iOCT after anterior chamber clearing had great prognostic value, excluding the need for surgical revision with a second general anesthesia in this young patient.

Intraoperative optical coherence tomography and ab interno trabecular meshwork surgery with the Trabectome

Importance

This study is the first description of the use of the intraoperative optical coherence tomography (iOCT) for trabecular meshwork surgery with the Trabectome in a regular clinical setting.

Background

The aim of this study is to evaluate intraoperatively the immediate success of ab interno trabeculotomy with the Trabectome defined as a removal of the trabecular meshwork.

Design

This is a retrospective clinical study performed in the University Eye Hospital, Medical School Hannover.

Participants

A total of nine consecutive Caucasian patients suffering from primary open angle glaucoma, pigment dispersion glaucoma, or pseudoexfoliation glaucoma took part in the study.

Methods

All patients underwent ab interno trabeculotomy surgery with the Trabectome using a commercially available iOCT to visualize the anterior chamber angle (ACA) before and after the procedure. The visualization was done using a modified Swan-Jacobs lens (all nine patients) or without lens (view from above, five patients).

Main outcome measures

The main outcome of this study is the success of visualization of the ACA on iOCT, especially the postprocedural visualization of the wound gap after removal of the trabecular meshwork.

Results

Using the view from above, the ACA could be visualized before and after the procedure in only two of the five cases. Using the modified Swan-Jacobs lens, the ACA could be visualized before the procedure and the trabecular meshwork opening after the procedure in all nine patients.

Conclusion

The iOCT can be used to objectify the immediate success of the surgical procedure, ie, the removal of the trabecular meshwork, of ab interno trabeculotomy with the Trabectome. The procedure itself cannot be captured sufficiently via iOCT.

[Intraoperative optical coherence tomography in retinal detachment]

BACKGROUND

Using intraoperative optical coherence tomography (iOCT) can be advantageous during macular surgery and lamellar keratoplasty. It is yet unknown if there is a distinct benefit in its application in retinal detachment surgery.

OBJECTIVE

What can be shown using iOCT during retinal detachment surgery? Can therapeutically relevant decisions be made and do they have a prognostic implication on postoperative results?

METHODS

Based on already published (11 patients/eyes) and our own new data (23 patients/eyes),findings by iOCT during retinal detachment surgery are presented.

RESULTS

Outer retinal corrugations are a frequent feature in iOCT in retinal detachment. These corrugations persist during the application of heavy liquids. Even when the retina seems clinically reattached under the use of perfluoroctane, there is significant subfoveal fluid. Using perfluordecaline, there seems to be less subfoveal fluid. In patients with retinal detachment and macula off situation, subclinical full thickness macular holes seem to be more common than assumed. It is unclear if their incidence is influenced by the use of heavy liquids. They appear to have a negative predictive value regarding postoperative visual acuity.

CONCLUSION

Even if there are no obvious benefits in using iOCT in retinal detachment surgery, this new technique offers deeper insights into the microarchitecture of the detached retina. Further investigations in more patients will show if the use of the iOCT will result in a better prognosis for our patients.

[Intraoperative optical coherence tomography in corneal and glaucoma surgical procedures]

BACKGROUND

Optical coherence tomography (OCT) is the clinical gold standard for anterior and posterior segment imaging. Since OCT devices have been integrated into surgical microscopes, this technique is also available intraoperatively in anterior segment surgery. OCT is well established in imaging very thin or transparent structures as they appear in corneal or glaucoma surgery. Therefore, intraoperative OCT can deliver important information for the surgeon which is superior to the normal surgical microscope.

OBJECTIVES

In the present work, an overview about the opportunities of intraoperative OCT in cornea and glaucoma surgery are presented.

MATERIAL AND METHODS

The recent literature (PubMed) and our own experience at the Center for Ophthalmology, University Hospital of Cologne are analysed.

RESULTS

Intraoperative OCT enables real-time imaging during corneal and glaucoma surgery. Several clinical studies exist, indicating its benefit, e. g. in DMEK, DALK, DSAEK, Boston Keratoprosthesis, canaloplasty or trabectome surgery. Several structures, not visible in the surgical microscope, can be visualized using intraoperative OCT.

CONCLUSIONS

As a real-time and high-resolution imaging device, intraoperative online OCT delivers additional information in glaucoma and corneal surgery, compared to the normal operating microscope. Nonetheless one of the main problems is the shadowing produced by surgical instruments. Today the main limitation is the lack of randomized-controlled clinical trials, evaluating the benefit of microscope-integrated intraoperative OCT, compared to the microscope.

Intraoperative OCT assisted descemetopexy with stromal vent incisions and intracameral gas injection for case of non-resolving Descemet's membrane detachment

Descemet's membrane detachment (DMD) though uncommon in the present day scenario of advancing surgical techniques is a significant complication that requires prompt diagnosis and management. A middle-aged man presented to our hospital with poor gain of vision following cataract surgery. There was significant corneal oedema with DMD which was confirmed on anterior segment optical coherence tomography. We describe a modified continuous intraoperative-guided approach for the management of DMD in cases with oedematous hazy corneas. The aim of this technique is to allow early reattachment of Descemet's membrane in chronic cases where fluid pockets prevent reattachment of the posterior layer of cornea. Our technique involves the use of full thickness stromal vent incisions in the paracentral cornea along with intracameral isoexpansile concentration of gas for the successful settlement of the detached Descemet's membrane.

Intraoperative Interface Fluid Dynamics and Clinical Outcomes for Intraoperative Optical Coherence Tomography-Assisted Descemet Stripping Automated Endothelial Keratoplasty From the PIONEER Study

PURPOSE

To correlate intraoperative interface fluid dynamics during Descemet stripping automated endothelial keratoplasty (DSAEK) using intraoperative optical coherence tomography (iOCT) in the Prospective Intraoperative and Perioperative Ophthalmic Imaging with Optical Coherence Tomography (PIONEER) study with postoperative outcomes.

DESIGN

Prospective consecutive, interventional, comparative case series.

PARTICIPANTS

One hundred seventy-eight eyes of 173 patients undergoing DSAEK from the Cole Eye Institute, Cleveland, Ohio.

METHODS

Eyes that underwent DSAEK between October 2011 and March 2014 from the PIONEER intraoperative and perioperative OCT study were included. An automated interface fluid segmentation algorithm evaluated intraoperative dynamics of interface fluid before and after surgical manipulations. iOCT images were also captured at multiple intraoperative time points for 2 different DSAEK techniques, 1 that used an active air infusion system and 1 that did not.

MAIN OUTCOME MEASURES

Interface fluid metrics, graft nonadherence.

RESULTS

iOCT measurements of interface fluid after final surgical manipulations and immediately before leaving the operating room identified that total fluid volume (P = .002), largest fluid volume pocket (P = .002), max fluid area (P = .006), mean fluid thickness (P = .03), and max fluid thickness (P = .01) significantly correlated with graft nonadherence rates within the first postoperative week. After placement and optimization of intraoperative lenticle adherence, iOCT revealed a significant difference between the area, volume, and thickness of maximum fluid pockets between the 2 surgical techniques, but both techniques resulted in significant reduction of interface fluid during the procedure.

CONCLUSIONS

Larger residual interface fluid volume, area, and thickness at the end of surgery detected with iOCT are associated with early graft nonadherence and can be quantified with an automated algorithm. iOCT imaging can successfully capture technique-dependent differences in fluid dynamics during DSAEK.

Evaluation of Time to Donor Lenticule Apposition Using Intraoperative Optical Coherence Tomography in Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

To evaluate the time to donor lenticule apposition in cases of Descemet stripping automated endothelial keratoplasty (DSAEK) using microscope-integrated intraoperative optical coherence tomography (iOCT).

METHODS

Thirty eyes of 27 patients planned to undergo Descemet stripping automated endothelial keratoplasty were enrolled in this prospective study. In group I (n = 10), continuous intracameral positive pressure was maintained for 8 minutes. In group II (n = 10) and group III (n = 10), external corneal massage was initiated simultaneously with positive intracameral air pressure. The external corneal massage was continued till complete resolution of interface fluid; the positive intracameral pressure was maintained for 8 minutes in group II and for 5 minutes in group III. The host-donor relationship was continuously monitored with the iOCT. The main outcome measure was time to complete donor lenticule apposition.

RESULTS

In group I, the interface fluid persisted after 8 minutes of positive intracameral pressure in all eyes (10/10); hence an external corneal massage was required to achieve optimal donor adherence. In groups II and III, all eyes (20/20) had complete resolution of the interface fluid at the end of 3 minutes. In 100% of the eyes (30/30), the grafts were attached after anterior chamber decompression as seen on the iOCT. In all cases, the donor lenticules were adhered in the postoperative period.

CONCLUSIONS

iOCT helps in understanding that the donor lenticule is well apposed within 1 to 3 minutes with the technique of simultaneous positive intracameral pressure and external corneal massage. This knowledge minimizes the waiting time for graft apposition and prevents prolonged intraocular pressure elevation.

Clinical utility of intraoperative optical coherence tomography

PURPOSE OF REVIEW

To explore the clinical utility of intraoperative optical coherence tomography (iOCT) for the management of vitreoretinal conditions.

RECENT FINDINGS

The role of iOCT in guiding surgical decision-making and surgical manipulations during vitreoretinal procedures has been evaluated by multiple studies. This imaging modality is emerging as a valuable asset during procedures for vitreoretinal interface disorders, retinal detachments, submacular surgeries and therapeutics, and in pediatric conditions such as retinopathy of prematurity. iOCT allows the surgeon to assess completion of surgical goals and to directly monitor the architectural impact of instrument-tissue interactions that may correlate with eventual prognosis. The technology has gone through numerous iterations with the eventual goal being the development of a user-friendly, efficient, and integrated system that provides surgeons with 'real-time' feedback during ophthalmic surgeries to allow for a comprehensive image-assisted vitreoretinal surgery platform.

SUMMARY

The role of iOCT in ophthalmic surgery has been evolving with the help of ongoing research to define its utility in the operating room and to develop integrative technologies. Advancements in OCT-friendly surgical instrumentation and in integrative capabilities of this technology may help achieve more widespread adoption of this technology in the vitreoretinal surgical theater. Although the evidence appears clear that this technology impacts surgical decision-making, additional research is needed. However, further research is needed to determine the influence of this technology on overall patient outcomes.

Intraoperative optical coherence tomography in descemet stripping automated endothelial keratoplasty: pilot experiences

Purpose

To assess the added value of intraoperative optical coherence tomography (iOCT) in evaluating graft adhesion and graft interface in patients undergoing descemet’s stripping automated endothelial keratoplasty (DSAEK).

Methods

This is a prospective single-center case series comprising 8 eyes of 8 patients consecutively scheduled for DSAEK surgery. iOCT imaging was performed after insertion of the graft, after pressurizing the eye, and at the end of surgery (three images per surgery). At each stage of surgery, corneal thickness and the widest gap between the recipient and the graft (i.e., maximal interface width) were measured using an image processing tool. Follow-up measurements were taken at 1 day, 3 and 6 months, post-operatively.

Results

Imaging was performed in 21 of 24 scheduled imaging intervals, and required little to no additional surgical time. At the end of surgery, iOCT showed persisting interfaces in six cases. One case showed a full graft detachment necessitating surgical intervention.

Conclusion

Real-time iOCT is a safe, efficient, and useful tool in assessing graft adherence in DSAEK surgery. With adequate analysis software, iOCT has the potential to be a paradigm-shifting development in posterior lamellar surgery and could aid the clinician in further lowering the rates of graft dislocation after DSAEK.

Intraoperative optical coherence tomography (RESCAN® 700) for detecting iris incarceration and iridocorneal adhesion during keratoplasty

There is no report focusing on the visualization of the iris incarceration or the iridocorneal adhesion during keratoplasty by use of microscope-integrated intraoperative optical coherence tomography (MIOCT). The purpose of this study is to report the usefulness of MIOCT for detecting iris incarceration and iridocorneal adhesions during penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK). MIOCT system was applied both in a patient who underwent PK for corneal leukoma and in a patient who underwent DALK for keratoconus. During the surgeries, we obtained cross-sectional images around the host-graft interface by operating the foot switch of microscope without discontinuing the surgical procedure. Intraoperative MIOCT findings and postoperative outcomes were examined. An iris incarceration at the host-graft interface was visualized during surgery after corneal suture in PK, which allowed surgeons to return the iris to its original position instantly. In DALK, misdirected air into the posterior chamber could also be seen at the end of the DALK. This iridocorneal adhesion was resolved by fluid injection through paracentesis. Secondary glaucoma and graft rejection have not occurred postoperatively in both cases. The MIOCT system provides advantages such as prevention of secondary glaucoma and rejection following PK and DALK.

Visualization of precut DSAEK and pre-stripped DMEK donor corneas by intraoperative optical coherence tomography using the RESCAN 700

BACKGROUND

To report the feasibility of intraoperative spectral domain optical coherence tomography (OCT) using the RESCAN 700 for the visualization and evaluation of precut Descemet's stripping automated endothelial keratoplasty (DSAEK) and prestripped Descemet's membrane endothelial keratoplasty (DMEK) donor tissue.

METHODS

Precut DSAEK (n = 11), prestripped DMEK (n = 4) preserved in a viewing chamber were examined by intraoperative OCT. Wholly intact donor corneas for penetrating keratoplasty (PK) (n = 8) were also examined as controls. The obtained images were analyzed qualitatively for characteristics of each type of donor.

RESULTS

For each type of donor, characteristic images were consistently obtained by intraoperative OCT in both the front and back views through the viewing chamber. In wholly intact donors for PK, appearance of normal corneal curvature and stromal texture with high reflectivity of epithelium and endothelium cell layers were clearly visualized. In precut DSAEK donors, precut lines were characteristically visualized in addition to the intact donor cornea images. In prestripped DMEK donors, identical OCT images to the intact donor cornea were noted when observed from the anterior surface. However, peripheral partial detachments of Descemet's membrane were characteristically observed in all prestripped DMEK donors when viewed from the back of the viewing chamber.

CONCLUSION

Rapid visualization and rough evaluation of donor tissues for PK, precut DSAEK and prestripped DMEK donor corneas by intraoperative OCT was consistently possible through the viewing chamber. Therefore, this device may be used as an alternative of AS-OCT when the eyebank does not have their own AS-OCT. Although the peripheral detachment in DMEK donors are quite common and clinically non-problematic in DMEK donor quality and subsequent DMEK surgeries, it may be useful to distinguish between wholly intact PK donors and prestripped DMEK donors, enabling to prevent mix-ups of donors, especially when several different types of keratoplasties are scheduled in a same day in one operating theater.

Real-time assessment of intraoperative vaulting in implantable collamer lens and correlation with postoperative vaulting

PURPOSE

To assess the intraoperative vaulting in patients undergoing implantable collamer lens (ICL) implantation with microscope-integrated intraoperative optical coherence tomography (iOCT) and correlate it with the postoperative vaulting.

METHODS

Forty eyes of 22 consecutive patients undergoing ICL implantation were prospectively evaluated. Vaulting was measured intraoperatively using microscope-integrated iOCT. The ICL-lenticular relationship was dynamically assessed throughout the surgery. Postoperative vaulting was measured using anterior segment optical coherence tomography on the first postoperative day and after 1 month and compared with the intraoperative vaulting. Uncorrected and best-corrected Snellen visual acuity, intraocular pressure (IOP), and anterior and posterior segments were assessed in all cases.

RESULTS

The mean central vaulting noted intraoperatively was 558.4 ± 122.8 µm. Postoperative mean vaulting was 576.0 ± 131.2 µm on day 1 and 551.1 ± 122.5 µm on day 30. There was a significant correlation between the intraoperative and the postoperative day 1 vaulting (paired samples correlation: 0.969, p&lt;0.001) and day 30 vaulting (paired samples correlation: 0.945, p&lt;0.001). An ICL-lenticular touch was not noted at any time during the surgery. The postoperative course was uneventful and no patient developed raised IOP or lenticular changes by the last follow-up.

CONCLUSIONS

Intraoperative vaulting correlates well with postoperative vaulting and can aid in on-table detection of extremes of vaulting and decision-making. It enhances the safety of the surgical procedure by providing a real-time display of the intraoperative manipulations.

Use of a new intra-ocular spectral domain optical coherence tomography in vitreoretinal surgery

PURPOSE

To describe the use of a novel intra-ocular side-scanning probe enabling the acquisition of spectral-domain optical coherence tomography (SD-OCT) images during surgery in a series of patients with complex forms of retinal detachment.

METHODS

A 23-gauge, side-scanning SD-OCT probe (C7 System; LightLab Imaging, Inc/St Jude Medical, St. Paul, MN, USA) in a 20-gauge catheter, was used to acquire the intra-operative OCT images in seven patients with vitreoretinal diseases. Twenty-five gauge pars plana vitrectomy (PPV) was performed in every patient in a standard fashion. After enlarging the temporal sclerotomy to a 20-gauge port, all the patients were scanned with intra-ocular side-scanning SD-OCT, during different steps of the surgery based on surgeon needs. Scans were recorded real time and directly evaluated on a screen during surgery. Optical coherence tomography (OCT) scans were judged beneficial when they would recognize structures otherwise not seen on biomicroscopy.

RESULTS

The intra-ocular SD-OCT has been helpful in acquiring extra information during vitreoretinal surgery such as the detection of the presence of otherwise invisible membranes (epiretinal membrane, subretinal membrane), the location of small tears and the identification of the retinal plane under suboptimal conditions for visualization.

CONCLUSION

The use of an intra-ocular SD-OCT can expand upon visual cues during surgery, helping in the decision-making process and allowing additional deliberate surgical manoeuvres aimed at improving surgical outcomes.

Intraoperative Optical Coherence Tomography for Enhanced Depth Visualization in Deep Anterior Lamellar Keratoplasty From the PIONEER Study

PURPOSE

Deep anterior lamellar keratoplasty (DALK) is a challenging procedure that often results in conversion to penetrating keratoplasty. Preservation of Descemet membrane (DM) relies on indirect visualization of surgical planes. We describe a technique for enhanced visualization of key steps in DALK with intraoperative optical coherence tomography.

METHODS

Using a microscope-mounted spectral domain optical coherence tomography system, high-resolution images of various steps were obtained.

RESULTS

Specifically, images were obtained of the trephination depth and proximity of the cannula tract to DM. Other key steps such as air cannula placement, assessment of the DM position and integrity after attempted big-bubble delivery, and assessment of graft-host apposition were readily visualized. The presence of intrastromal emphysema after air injection decreased visualization of deeper structures.

CONCLUSIONS

Intraoperative optical coherence tomography allows visualization of depth-dependent anatomy and changes from specific surgical interventions during DALK not appreciated with the en face operating microscope view and has the potential to facilitate big-bubble delivery. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT02423161.

Determination of feasibility and utility of microscope-integrated optical coherence tomography during ophthalmic surgery: the DISCOVER Study RESCAN Results

IMPORTANCE

Optical coherence tomography (OCT) has transformed the clinical management of a myriad of ophthalmic conditions. Applying OCT to ophthalmic surgery may have implications for surgical decision making and patient outcomes.

OBJECTIVE

To assess the feasibility and effect on surgical decision making of a microscope-integrated intraoperative OCT (iOCT) system.

DESIGN, SETTING, AND PARTICIPANTS

Report highlighting the 1-year results (March 2014-February 2015) of the RESCAN 700 portion of the DISCOVER (Determination of Feasibility of Intraoperative Spectral Domain Microscope Combined/Integrated OCT Visualization During En Face Retinal and Ophthalmic Surgery) study, a single-site, multisurgeon, prospective consecutive case series regarding this investigational device. Participants included patients undergoing ophthalmic surgery. Data on clinical characteristics were collected, and iOCT was performed during surgical milestones, as directed by the operating surgeon. A surgeon questionnaire was issued to each surgeon and was completed after each case to evaluate the role of iOCT during surgery and its particular role in select surgical procedures.

MAIN OUTCOMES AND MEASURES

Percentage of cases with successful acquisition of iOCT (ie, feasibility). Percentage of cases in which iOCT altered surgical decision making (ie, utility).

RESULTS

During year 1 of the DISCOVER study, a total of 227 eyes (91 anterior segment cases and 136 posterior segment cases) underwent imaging with the RESCAN 700 system. Successful imaging (eg, the ability to acquire an OCT image of the tissue of interest) was obtained for 224 of 227 eyes (99% [95% CI, 98%-100%]). During lamellar keratoplasty, the iOCT data provided information that altered the surgeon's decision making in 38% of the cases (eg, complete graft apposition when the surgeon believed there was interface fluid). In membrane peeling procedures, iOCT information was discordant with the surgeon's impression of membrane peel completeness in 19% of cases (eg, lack of residual membrane or presence of occult membrane), thus affecting additional surgical maneuvers.

CONCLUSIONS AND RELEVANCE

The DISCOVER study demonstrates the feasibility of real-time iOCT with a microscope-integrated iOCT system for ophthalmic surgery. The information gained from iOCT appears to allow surgeons to assess subtle details in a unique perspective from standard en face visualization, which can affect surgical decision making some of the time, although the effect of these changes in decision making on outcomes remains unknown. A prospective randomized masked trial is needed to confirm these results.

Intraoperative optical coherence tomography: past, present, and future

To provide an overview of the current state of intraoperative optical coherence tomography (OCT). Literature review of studies pertaining to intraoperative OCT examining both the technology aspects of the imaging platform and the current evidence for patient care. Over the last several years, there have been significant advances in integrative technology for intraoperative OCT. This has resulted in the development of multiple microscope-integrated systems and a rapidly expanding field of image-guided surgical care. Multiple studies have demonstrated the potential role for intraoperative OCT in facilitating surgeon understanding of the surgical environment, tissue configuration, and overall changes to anatomy. In fact, the PIONEER and DISCOVER studies, both demonstrated a potential significant percentage of cases that intraoperative OCT alters surgical decision-making in both anterior and posterior segment surgery. Current areas of exploration and development include OCT-compatible instrumentation, automated tracking, intraoperative OCT software platforms, and surgeon feedback/visualization platforms. Intraoperative OCT is an emerging technology that holds promise for enhancing the surgical care of both anterior segment and posterior segment conditions. Hurdles remain for adoption and widespread utilization, including cost, optimized feedback platforms, and more definitive value for individualized surgical care with image guidance.

Wavelike Interface Opacities After Descemet-Stripping Automated Endothelial Keratoplasty: 7-Year Follow-up

PURPOSE

To report a case of wavelike interface opacities in a patient who underwent Descemet-stripping automated endothelial keratoplasty (DSAEK) and was managed conservatively over the course of 7 years.

METHODS

A 65-year-old woman underwent DSAEK for pseudophakic bullous keratopathy. Textural wavelike opacities were noted in the graft-host interface 6 days postoperatively without evidence of anterior segment inflammation. The patient's vision was also initially limited by the presence of cystoid macular edema (CME). Six months postoperatively, CME had resolved but the patient's vision failed to improve better than 20/80 because of the persistent dense interface opacities. The patient refused to undergo graft exchange despite a suboptimal visual result and she therefore was observed over time.

RESULTS

The interface opacities started to regress and her visual acuity improved to 20/30 by 9 months postoperatively. The opacities became gradually less prominent over the next few years, and at 7 years postoperatively, her best-corrected vision was 20/25.

CONCLUSION

In this case, observation of this post-DSAEK complication rather than surgical intervention resulted in a favorable long-term visual outcome.

Preliminary Design and Evaluation of a B-Scan OCT-Guided Needle

Real-time intraoperative B-scan optical coherence tomography (OCT) visualization of intraocular tissues is a desired ophthalmic feature during retinal procedures. A novel intraocular 25-gauge B-mode forward-imaging OCT probe was combined with a 36-gauge needle into a prototype instrument. Imaging of the needle tip itself and the effects of saline injection into a gelatin phantom were performed. A combined B-scan forward-imaging OCT-needle prototype was capable of real-time-imaging of saline injection into a gelatin phantom. Additional future miniaturization may permit this instrument to be an adjunctive realtime imaging and procedure tool for vitreoretinal surgery.

Descemet membrane endothelial keratoplasty: intraoperative and postoperative imaging spectral-domain optical coherence tomography

We describe a case report of using the same handheld spectral-domain anterior segment optical coherence tomography (ASOCT) for rapid intraoperative and postoperative imaging in a case of Descemet membrane endothelial keratoplasty (DMEK). A 67-year-old woman, with Fuchs dystrophy and corneal decompensation, underwent DMEK with intraoperative ASOCT imaging using the handheld Envisu spectral domain ASOCT system (Bioptigen, Inc., Morrisville, NC, USA). We found that this easy-to-use portable system with handheld probe allowed for rapid imaging of the anterior segment during donor manipulation to visualize the orientation of the DMEK donor, as well as to confirm the initial adhesion of the DMEK donor. Moreover, the same system may be used for postoperative monitoring of graft adhesion, corneal thickness, and stromal remodeling in the clinic with very high-definition images.