Intraoperative Optical Coherence Tomography Research Articles

Peripheral Cystoid Degeneration Finding Using Intraoperative Optical Coherence Tomography in Rhegmatogenous Retinal Detachment

PurposeThe interaction between the peripheral vitreous and retina is closely associated with the pathogenesis of rhegmatogenous retinal detachment (RRD). This study was conducted to examine the peripheral vitreous and retina in patients with RRD using intraoperative optical coherence tomography (iOCT).MethodsThis retrospective study included 50 eyes of 50 patients (mean age 59.42 ± 10.80 years) that underwent vitrectomy using iOCT for treating RRD at the Yamagata University Hospital between September 2015 and September 2016. Each patient underwent 25-gauge pars plana vitrectomy that was performed by a single surgeon. During vitreous shaving with ocular indentation, the iOCT findings of the peripheral vitreous and retina were recorded and analyzed postoperatively.ResultsIn all patients, iOCT was able to detect the peripheral retina and vitreous around the vitreous base. Peripheral cystoid degeneration was detected on the peripheral retina of 27 eyes (54%). Furthermore, cystoid degeneration was detected around the retinal tear (5 patients), at the detached retinal area (8 patients), and at the attached retinal area (14 patients).ConclusioniOCT enabled the evaluation of peripheral cystoid degeneration in patients with RRD. Cystoid degeneration might be associated with the pathogenesis of RRD.

Intraoperative Retinal Changes May Predict Surgical Outcomes After Epiretinal Membrane Peeling.

PurposeTo investigate whether intraoperative retinal changes during epiretinal membrane (ERM) peeling affect anatomic or functional outcomes after surgery.MethodsWe measured retinal thickness using an intraoperative optical coherence tomography (iOCT) device in patients undergoing pars plana vitrectomy with membrane peeling for idiopathic ERM. Changes in intraoperative central macular thickness (iCMT) were compared with postoperative improvements in CMT and best-corrected visual acuity (VA).ResultsTwenty-seven eyes from 27 patients (mean age 68 years) underwent iOCT-assisted ERM peeling surgery. Before surgery, mean VA was logMAR 0.50 ± 0.36 (Snellen 20/63), and mean baseline CMT was 489 ± 82 µm. Mean iCMT before peeling was 477 ± 87 µm, which correlated well with preoperative CMT (P < 0.001). Mean change in iCMT was −39.6 ± 37 µm (range −116 to +77 µm). After surgery, VA improved to logMAR 0.40 ± 0.38 (Snellen 20/50) at month 1 and logMAR 0.27 ± 0.23 (Snellen 20/37) at month 3, whereas CMT decreased to 397 ± 44 µm and 396 ± 51 µm at months 1 and 3. Eyes that underwent greater amount of iCMT change (absolute value of iCMT change) were associated with greater CMT reduction at month 1 (P < 0.001) and month 3 (P = 0.010), whereas those with greater intraoperative thinning (actual iCMT change) showed a trend toward better VA outcomes at months 1 (P = 0.054) and 3 (P = 0.036).ConclusionsIntraoperative changes in retinal thickness may predict anatomic and visual outcomes after idiopathic ERM peeling surgery.Translational RelevanceOur study suggests that intraoperative retinal tissue response to ERM peeling surgery measured by iOCT may be a prognostic indicator for restoration of retinal architecture and for visual acuity outcomes.

Quantification of the peripheral vitreous after vitreous shaving using intraoperative optical coherence tomography

ObjectiveTo evaluate the technique of peripheral vitreous shaving during vitrectomy, we measured the residual peripheral vitreous using intraoperative optical coherence tomography (iOCT).Methods and AnalysisThis retrospective study included 44 eyes that...

Real-time tool to layer distance estimation for robotic subretinal injection using intraoperative 4D OCT.

The emergence of robotics could enable ophthalmic microsurgical procedures that were previously not feasible due to the precision limits of manual delivery, for example, targeted subretinal injection. Determining the distance between the needle tip, the internal limiting membrane (ILM), and the retinal pigment epithelium (RPE) both precisely and reproducibly is required for safe and successful robotic retinal interventions. Recent advances in intraoperative optical coherence tomography (iOCT) have opened the path for 4D image-guided surgery by providing near video-rate imaging with micron-level resolution to visualize retinal structures, surgical instruments, and tool-tissue interactions. In this work, we present a novel pipeline to precisely estimate the distance between the injection needle and the surface boundaries of two retinal layers, the ILM and the RPE, from iOCT volumes. To achieve high computational efficiency, we reduce the analysis to the relevant area around the needle tip. We employ a convolutional neural network (CNN) to segment the tool surface, as well as the retinal layer boundaries from selected iOCT B-scans within this tip area. This results in the generation and processing of 3D surface point clouds for the tool, ILM and RPE from the B-scan segmentation maps, which in turn allows the estimation of the minimum distance between the resulting tool and layer point clouds. The proposed method is evaluated on iOCT volumes from ex-vivo porcine eyes and achieves an average error of 9.24 µm and 8.61 µm measuring the distance from the needle tip to the ILM and the RPE, respectively. The results demonstrate that this approach is robust to the high levels of noise present in iOCT B-scans and is suitable for the interventional use case by providing distance feedback at an average update rate of 15.66 Hz.

Heads-up Digitally Assisted Surgical Viewing with Intraoperative Optical Coherence Tomography for Myopic Schisis Repair.

PurposeTo describe the surgical approach with a screen-based heads-up, three-dimensional (3-D) digital viewing with intraoperative optical coherence tomography (I-OCT) for the successful repair of a myopic macular schisis (MMS) case.Case ReportA 62-year-old woman with vision loss in the left eye was scheduled for pars plana vitrectomy (PPV) and MMS repair. Surgery was performed using the NGENUITYⓇ system for surgical viewing, and foveal-sparing internal limiting membrane (fs-ILM) peeling was performed without gas tamponade, after confirming the absence of iatrogenic macular hole with I-OCT. There were no intraoperative or postoperative complications. Visual acuity improved to 20/40 and the subfoveal macular thickness improved from 706 µm (preoperative) to 221 µm after seven months of follow-up.ConclusionHeads-up digitally assisted viewing technology with I-OCT may be useful or preferred for patients requiring vitreoretinal surgery in the setting of MMS.

Intraoperative optical coherence tomography-assisted displacement of prepapillary membrane in eyes with optic disc pit maculopathy.

To determine the efficacy of displacing a prepapillary membrane during vitrectomy assisted by intraoperative optical coherence tomography (OCT) to treat eyes with optic disc pit maculopathy. Pars plana vitrectomy was performed with 27-gauge instruments on 4 eyes of 4 consecutive patients for optic disc pit maculopathy with retinoschisis and foveal detachment. After creating a posterior vitreous detachment, the prepapillary membrane was made visible by brilliant blue G staining. The membrane was peeled from the central retinal vessel and inverted and placed over intraretinal clefts or stuffed into the optic disc pit. These procedures were guided by intraoperative OCT. A gas tamponade and peripapillary laser was not used. The preoperative and postoperative OCT images and surgical outcomes were evaluated. Intraretinal clefts connected to an inner retinoschisis were detected at the edge of the optic disc pit in 3 eyes with intraoperative OCT and 2 eyes with preoperative OCT. The foveal detachment and retinoschisis were resolved completely in all 4 eyes at postoperative 13 to 15 months. The postoperative vision improved from 20/25 to 20/18 at the final examination in all eyes. Intraoperative OCT can detect intraretinal clefts at the edge of the optic disc pit, and the OCT images are helpful in guiding the peeling and placement of the prepapillary membrane to achieve anatomical and visual recovery.

The effects of laser displacement on femtosecond laser-assisted conjunctival autograft preparation for pterygium surgery.

AimsTo evaluate the effects of no-suction femtosecond laser (FSL) stability on conjunctival autograft (CAG) dissection in pterygium surgery.MethodsProspective analysis of 35 eyes from 34 subjects who underwent femtosecond laser-assisted pterygium surgery with the Ziemer Z8 laser (Ophthalmic Systems AG, Switzerland). Intraoperative absolute FSL displacements were measured and correlated with the duration and ease of CAG peel, CAG thickness, measured with intraoperative optical coherence tomography, and deviation from intended graft thickness.ResultsThe median absolute FSL displacement was 22 μm (interquartile range [IQR] 14.7 to 60.8), while median vertical FSL displacement was 14.7 μm (IQR 7.3 to 44) and median horizontal FSL displacement was 22.0 μm (IQR 14.7 to 44). 65.7% had a grade 1 peel, 11.4% had grade 2 peel, 14.3% had grade 3 peel and 8.6% had grade 4 peel. The median duration of CAG peel was 5.4 seconds (IQR 3 to 21.4). The median CAG thickness was 69 μm (IQR 60.3 to 78.5), and the median deviation from targeted graft thickness was 9 μm (IQR 1 to 16). Eyes with more difficult peels and longer duration of CAG peels had significantly greater vertical FSL displacements (p = 0.04 and 0.02 respectively), but not horizontal displacement, age, ethnicity, CAG thickness or deviation from original thickness, compared to those with better quality and shorter duration peels. 1 eye (2.9%) had an incomplete CAG peel with a buttonhole and 2 eyes had graft tears (5.7%).ConclusionMicro-displacements during the suction-free CAG preparation are common but they did not affect the quality of the CAG peel, duration of peel, or CAG thickness. However, vertical globe displacement during FSL-assisted CAG creation was significantly associated with a more difficult and longer CAG peel duration. This highlights the importance of the cornea traction suture fixation to ensure stability of the eye during FSL application.

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.

Study 3: Assessment of events during surgery on posterior polar cataracts using intraoperative optical coherence tomography.

Purpose:To describe the changes along nucleo-epinuclear and the opacity-capsular junction during hydrodelineation and the entire period of phacoemulsification using intraoperative optical coherence tomography (iOCT).Methods:A total of 12 eyes of 12 patients with clinically confirmed posterior polar cataract, who underwent cataract surgery by a single surgeon under the direct guidance of iOCT. The changes along nucleo-epinuclear junction and opacity-capsular junction during/following hydrodelineation and the changes along the opacity-capsular junction following nucleus removal, capsular changes before the opacity removal, and its dynamic changes throughout the surgical procedure were studied.Results:The mean age of patients was 48.25 ± 7.89 years. Eight of them were males and the right eye was operated in seven patients. With regular hydrodelineation, optimal separation of the nucleus-epinuclear layer was evident in 11 patients. Once a golden ring is achieved through the hydro procedure, then repeated attempts can be performed within it to decrease the chances of capsular damage. Fracture of the posterior opacity with tension over the underlying capsule (n = 1), inadvertent hydro dissection while performing hydrodelineation (n = 1), continuous posterior capsular billowing (n = 2), and posterior capsular ruptures (n = 2) were encountered in this observation with even well-judged surgical maneuvering.Conclusion:iOCT provides a better understanding of real-time changes along different layers of the human lens during posterior polar cataract surgery. The observations obtained here are likely to help in minimizing inadvertent complications in the future.

Intraoperative optical coherence tomography (I-OCT)-guided identification of resolved sub-internal limiting membrane hemorrhage in leukemic retinopathy

Intraoperative optical coherence tomography (I-OCT)-guided identification of resolved sub-internal limiting membrane hemorrhage in leukemic retinopathy

Swept source intraoperative OCT angiography

To accurately guide surgical instruments during ophthalmic procedures, some necessary intraoperative depth perception is required, which standard surgical microscopes supply limitedly. Intraoperative optical coherence tomography (iOCT), combining optical coherence tomography (OCT) technology and surgical microscope, enables noninvasive, real-time and high-resolution cross-sectional imaging. Currently, though iOCT enables structural imaging, little research has been done on intraoperative angiography. In this work, we presented a swept-source intraoperative OCT angiography (SS-iOCTA) system based on a standard surgical microscope, which provides both structural and angiographic images. The feasibility of the proposed SS-iOCTA was confirmed through deep anterior lamellar keratoplasty (DALK) of ex vivo porcine eyes and blood perfusion imaging of in vivo rat cortex. High-resolution intraoperative feedback, including sub-surface structure and angiogram of biological tissue, can be visualized simultaneously with the SS-iOCTA system, which expand the surgeon’s capabilities and could be widely used in clinical surgery.

Integrated Intraoperative Optical Coherence Tomography for Pediatric Lamellar Corneal Transplant Surgery.

Integrated intraoperative anterior segment optical coherence tomography is an extremely valuable tool that can be used by corneal surgeons when performing pediatric lamellar corneal transplant surgery. This chapter will demonstrate its use in infants and children with a variety of corneal diseases. These diseases include congenital corneal opacities such as Peters' anomaly (both types I and II), surgical management of limbal dermoids, and its use in selective corneal transplant surgery such as DALK (deep anterior lamellar keratoplasty) or DSEK (Descemet stripping endothelial keratoplasty). These techniques could be used in children with anterior corneal scarring or storage disorders, such as mucopolysaccharidoses, or posterior endothelial disease, such as congenital hereditary endothelial dystrophy or posterior polymorphous dystrophy. This chapter will demonstrate the author's experience using this device during anterior segment corneal surgery.

Use of Integrated Intraoperative Ocular Coherence Tomography in Pediatric Cataract Surgery: Thinking outside the Box.

The advent of integrated intraoperative optical coherence tomography (i2OCT) has opened the door for safer and more complex surgeries in the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in pediatric cataract surgery in circumstances that are not traditionally considered for i2OCT use. The specific circumstances include: evaluation and treatment of a child following cataract extraction with lens implantation who has failed two attempts at YAG capsulotomy; lysis of post-trauma keratolenticular adhesion in an opaque cornea; surgical removal of secondary lens epithelial cell proliferation after pediatric cataract extraction with lens implantation, and identification of posterior capsular openings and defects. In each case the use of i2OCT allowed the procedure to be completed safely and successfully or informed the surgeon, allowing modification of the surgical decision tree.

Pediatric Vitreoretinal Surgery and Integrated Intraoperative Optical Coherence Tomography.

Intraoperative portable handheld and microscope-integrated OCT enhance the pediatric vitreoretinal surgeon's diagnostic abilities during examination under anesthesia and surgery, particularly in children who are challenging to examine preoperatively due to young age or ocular trauma. Improved OCT-guided visualization of vitreoretinal anatomic relationships has the potential to improve surgical safety and efficiency. In retinopathy of prematurity and other pediatric retinal vascular conditions, intraoperative OCT can be critical for distinguishing between retinoschisis and retinal detachment and highlighting abnormalities of the vitreoretinal interface that may contribute to development of tractional retinal detachments. During retinal detachment repair, intraoperative OCT aids identification of subtle retinal breaks, residual subretinal fluid, retained perfluorocarbon, preretinal membranes, and residual hyaloid, among other findings. In macular surgery, intraoperative OCT has demonstrated value in confirming completion or lack thereof of epiretinal and internal limiting membrane peeling and differentiating between lamellar and full-thickness macular holes. OCT-guided subretinal bleb formation and genetic vector delivery are critical to ensuring accurate localization of subretinal gene delivery for inherited retinal degenerations. Research on development of OCT-compatible surgical instruments, real-time three-dimensional volumetric OCT imaging, and integration with intraoperative OCT angiography are anticipated to further increase the utility of intraoperative OCT in pediatric vitreoretinal surgical decision-making.

The Use of Optical Coherence Tomography as an Intraoperative Adjunct of Oculoplastic Surgery.

The advent of integrated intraoperative optical coherence tomography (i2OCT) has opened the door for safer and more complex surgeries in the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in oculoplastic surgery. It can be used in cases of severe symblepharon where the cornea is heavily involved, so that the surgeon is aware of the depth of the pannus when trying to remove it. It can also be used when the corneal planes are difficult to identify. In oculoplastic surgery the technology allows for identification of tissue planes when en face visualization is difficult due to developmental abnormalities and repeated surgeries. Our experience reflects some of the many uses of iOCT in ophthalmic surgery, highlighting its added value in surgical precision.

Effect of intraoperative optical coherence tomography on anatomic and cosmetic results of intrastromal tattooing.

PURPOSE:The aim of the study was to evaluate the effect of intraoperative optical coherence tomography (i-OCT) on anatomic and cosmetic outcomes of intrastromal keratopigmentation (i-KTP) performed by novice lamellar corneal surgeons.METHODS:Thirty patients presenting with unilaterally disfiguring corneal scar and nil visual prognosis were subjected to i-OCT-guided intrastromal tattooing with rotring ink, by ophthalmology residents undergoing training in corneal surgeries at our center, who were later asked for a subjective feedback and mean stromal depth dissected was measured objectively. All patients were followed up for 9 months after surgery, and the subjective satisfaction of the patient, an independent observer, and surgeon was graded as poor, good, and excellent.RESULTS:The mean age of the patients was 29.53 ± 13.82 years (8–56 years). The most common cause of corneal opacity was healed keratitis with (6/30) or without (3/30) adherent leukoma, trauma-induced ocular disfigurement (7/30), and bullous keratopathy (6/30). All residents reported that feed-back images on i-OCT were “helpful” in all eyes and “very helpful” in eyes with corneal thinning, stromal scarring, adherent leukoma, bullous keratopathy, and hypotony. The mean depth of lamellar dissection was 51.16% ±4.62% of preoperative corneal thickness. The cosmetic results as perceived by the patient, an independent observer, and the surgeon were excellent and good in 23 and 7, 26 and 4, and 20 and 10 patients, respectively.CONCLUSION:I-KTP may be employed as a primary method of cosmetic correction of unsightly corneal scars. Centers equipped with i-OCT may employ this tool for teaching i-KTP to their ophthalmology residents for better surgical results with minimal complications.

Current Knowledge about the Anterior Interface in Children Operated for Congenital Cataract.

The relationship between the anterior vitreous interface and the posterior capsule has received increasing attention in the past decade. The advent of integrated intraoperative optical coherence tomography has allowed a real-time opportunity to grasp this dynamic understanding. Here we describe the normal anatomy of this interface in children and then demonstrate the variation in this interface with different forms of pediatric cataract, namely a posterior plaque and posterior capsular opacity due to abnormal adherence to the vitreous face. The authors describe these changes using meticulous annotation. An understanding of these differences will aid the surgeon in managing pediatric cataracts in a more confident and safe manner.

Integrated Intraoperative Optical Coherence Tomography in Pediatric Glaucoma Surgery.

The advent of integrated intraoperative optical coherence tomography (i2OCT) has opened the door for safer and more complex surgeries in the retina and cornea. However, to limit its use to just two subspecialties within ophthalmology is an opportunity lost for many other subspecialties. Here, we describe the use of i2OCT in pediatric glaucoma surgery. It can be used to identify Schlemm's canal, Barkan's membrane, demonstrate the corneal pathology in Haab's striae, and iris hypoplasia in cases of Axenfeld-Rieger anomaly. It can help identify drainage blebs that are filtering and those that are not, and identify successful drainage tube flushing. It has also been used to identify a ligating suture effect on a drainage tube. We describe these scenarios in relation to training and augmenting surgical techniques.

Intraoperative Optical Coherence Tomography: Game-Changing Technology.

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.

Correlation of Intraoperative Optical Coherence Tomography of Crystalline Lens Diameter, Thickness, and Volume with Biometry and Age

To characterize crystalline lens dimensions derived from invivo spectral-domain optical coherence tomography (SD-OCT) and identify associations among these parameters, ocular biometry, and age. In this retrospective study, lens thickness (LT), lens diameter (LD), and lens volume (LV) were measured intraoperatively using SD-OCT in 293 eyes undergoing lens surgery. Correlations among LT, LD, LV, age, axial length (AL), and anterior chamber depth (ACD) were analyzed. Multiple regression analysis was performed to determine whether a combination of biometric data could predict LD and LV. Wide variations were observed in LT (3.6-5.7mm), LD (7.5-11.9mm), and LV (119.9-312.4mm3) of aging eyes. Correlations among the 3 lens dimensions were statistically significant (LV-LT: r= 0.785; P < .001; LV-LD: r= 0.696; P < .001; and LT-LD: r= 0.121; P= .039). With age, the correlation coefficients of LT, LD, and LV were 0.526, 0.326, and 0.573, respectively (P < .001). Although there was significant correlation of AL with LT (r=-0.137; P= .002) and LD (r= 0.268; P < .001), it was not significant with LV (r= 0.084; P= .15). Subgroup analysis revealed that 19.8% of long eyes had LD >1 standard deviation (SD) above and that 5.2% had LD <1 SD below the mean LD. Dimensions of the aging lens vary considerably and are most accurately characterized by direct measurement of LT, LD, and LV, rather than making assumptions based on AL. These findings challenge historically proposed relationships between LD and AL and represent a normative dataset of contemporary geometric features of the aging lens, possibly aiding in surgical decision making and future developments in lens surgery.