Intraoperative Optical Coherence Tomography Research Articles

Analysis of retinal alterations utilizing intraoperative OCT following surgical interventions with novel ILM forceps in the DISCOVER study

This study aimed to assess retinal alterations following membrane peeling procedures using novel ILM Forceps with laser ablated surface with the help of intraoperative optical coherence tomography (iOCT). A post-hoc analysis was performed to evaluate iOCT findings in eyes that underwent membrane peeling procedures with the novel ILM Forceps. Pre-peel and post-peel iOCT videos and images were evaluated for each eye to assess for post-peel anatomic alterations. Surgical video/iOCT scan correlation was conducted to evaluate the etiology of anatomic alterations. Thirty-two eyes were included in the analysis. Three eyes (9%) had focal full thickness retinal elevations identified on iOCT following tissue-instrument interaction with the ILM Forceps. Two eyes (6%) had focal inner retinal elevations and one eye (3%) had a full-thickness retinal elevation that were not related to direct tissue-instrument interaction but rather indirect peeling forces. iOCT-identified architectural alterations related to direct-tissue instrument interaction were relatively infrequent (< 10%) with similar frequency to previously reported alterations with other surgical instruments.

Preoperative, Intraoperative and Post-Operative Optical Coherence Tomography for Pediatric Epiretinal Membranes Presenting with Strabismus

Abstract Purpose To highlight the value of optical coherence tomography (OCT) in the surgical decision making process of pediatric epiretinal membranes (ERMs). Methods A retrospective interventional case series that included the review of records of pediatric cases with ERMs presenting with strabismus who underwent pars plana vitrectomy by a single surgeon from March 2018 till June 2022. Demographic, clinical, and surgical details were extracted, as well as follow-up visits and outcomes. Results Five eyes of 5 cases with unilateral squint secondary to ERM were included. Age at presentation ranged from 2-7 years (mean 3.6 +/- 1.9), The male to female ration was 4:1. Two cases (40%) were idiopathic, 2 (40%) were secondary to familial exudative vitreoretinopathy (FEVR) and 1 (20%) was secondary to traumatic rupture globe. Preoperative and postoperative OCT was obtained in all cases, while preoperative fundus fluorescein angiography was obtained in 4 cases (80%). Intraoperative OCT was used in 4 cases (80%) to confirm complete release of the membrane from the fovea, and ILM was peeled in 3 cases (60%). The decision for surgical intervention and plan of surgery was totally dependent on preoperative OCT to confirm the extent of the ERM and the plane of cleavage. Intraoperative OCT helped assess areas of strong adherence of the membrane to avoid iatrogenic retinal injury. Initial restoration of the foveal anatomy with appearance of the fovea was seen after 3.6 +/- 2.8 months from the surgery with a range of 1-8 months. Squint improvement was seen in all cases. Time range to squint improvement was 1-4 months (mean 2.8 +/- 1.6). One case (20%) continued 4 years of follow up and two cases (40%) terminated follow up at 6 months due to squint improvement. Only one case (20%) showed progressive myopia post-surgery and one case did not achieve complete restoration of the fovea. Conclusion Surgical removal of pediatric epiretinal membranes presenting with strabismus leads to squint and visual improvement even if complete restoration of the foveal anatomy has not been reached yet. Combined use of preoperative, intraoperative and postoperative OCT in those cases helps better surgical and anatomical outcomes.

Intraoperative OCT-Guided Volumetric Measurements of Subretinal Therapy Delivery in Humans

Purpose: To evaluate a recently developed technique using intraoperative optical coherence tomography (OCT) to measure subretinal tissue plasminogen activator (tPA) volumes in patients with submacular hemorrhage secondary to exudative age-related macular degeneration (AMD). Methods: Three patients (72 to 83 years old) had 25-gauge pars plana vitrectomy, subretinal tPA, and a partial gas fill. An investigational intraoperative OCT system with a modified widefield noncontact indirect viewing apparatus was used to image subretinal tPA blebs. Using the recently developed technique, the volume and surface area in the segmented region of interest were determined. Results: In each case, the delivered tPA volume measured from the syringe differed from the intraoperative OCT–measured subretinal tPA volume: Patient 1, 130 µL from syringe, 118 µL based on intraoperative OCT, 9% difference; Patient 2, 140 µL, 50 µL, 64%; Patient 3, 110 µL, 122 µL, 11%. The total bleb surface area was 129 mm2 in Patient 1, 55 mm2 in Patient 2, and 106 mm2 in Patient 3. Conclusions: This was the first human study to implement and evaluate intraoperative OCT image–based methods to obtain volumetric bleb measurements in patients receiving subretinal tPA for exudative AMD. This proof-of-concept study showed that intraoperative OCT–obtained bleb volume differed from intraoperative recordings, which could be explained by tPA delivery into the vitreous, efflux through the retinotomy, or human error. Intraoperative OCT can provide visualization and quantification of subretinal tPA bleb volume and surface area, which has implications for improved safety, efficacy, and analysis of the effects of subretinal drug delivery.

Heads-up 3-dimensional-visualization system and integrated intraoperative optical coherence tomography in infantile vitreoretinal surgeries

ObjectiveTo demonstrate initial experience of Heads-up 3-dimensional-visualization system and integrated intra operative optical coherence tomography (iOCT) in a spectrum of complex infantile vitreoretinal surgeries. MethodsTwo different 3-D-visualization systems were used during the surgery on case-to-case basis and iOCT was used as needed. The vitrectomy system used was the same for all the surgeries. The disease spectrum included retinal disorders due to retinopathy of prematurity, familial exudative vitreoretinopathy, and retinitis. DesignDescriptive case series of surgeries operated under 3-D visualization and conventional microscope. ResultsA total of 10 eyes of 7 patients were included; out of which 5 eyes of 4 unique cases were operated under 3-D-visualization system and remaining 5 eyes of other 3 cases under the conventional microscope. The cases present our initial experience of the 3-D visualization and iOCT system over the conventional microscope with appropriate imaging and surgical videos. ConclusionInfantile vitreoretinal surgeries are difficult to teach, require an ergonomic friendly surgical environment and unpredictable surgical adjustments, which are the chief advantages of the discussed technologies. Heads-up 3-D-visualization system and iOCT appeared to be powerful new tools that can be explored further for use in complex infantile vitreoretinal surgeries.

Autonomous Needle Navigation in Subretinal Injections via iOCT.

Subretinal injection is an effective method for direct delivery of therapeutic agents to treat prevalent subretinal diseases. Among the challenges for surgeons are physiological hand tremor, difficulty resolving single-micron scale depth perception, and lack of tactile feedback. The recent introduction of intraoperative Optical Coherence Tomography (iOCT) enables precise depth information during subretinal surgery. However, even when relying on iOCT, achieving the required micron-scale precision remains a significant surgical challenge. This work presents a robot-assisted workflow for high-precision autonomous needle navigation for subretinal injection. The workflow includes online registration between robot and iOCT coordinates; tool-tip localization in iOCT coordinates using a Convolutional Neural Network (CNN); and tool-tip planning and tracking system using real-time Model Predictive Control (MPC). The proposed workflow is validated using a silicone eye phantom and ex vivo porcine eyes. The experimental results demonstrate that the mean error to reach the user-defined target and the mean procedure duration are within an acceptable precision range. The proposed workflow achieves a 100% success rate for subretinal injection, while maintaining scleral forces at the scleral insertion point below 15mN throughout the navigation procedures.

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

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

Interface fluid syndrome caused by the corneal perforation injury after small incision lenticule extraction: a case report

BackgroundTo report a case of interface fluid syndrome (IFS) following traumatic corneal perforation repair after small incision lenticule extraction (SMILE).Case presentationA 23-year-old woman, with a past history of SMILE, was struck in the left eye with a barbecue prod and subsequently underwent corneal perforation repair at local hospital. Primary wound repaired with a single 10 − 0 nylon suture at the area of leakage. After the surgery, her best corrected visual acuity (BCVA) was 20/30. Four days later, she presented at our hospital with blurred vision, and interface fluid syndrome (IFS) was diagnosed. Intraoperative optical coherence tomography (iOCT) was used to guide the resuturing of the corneal perforation in the left eye, followed by anterior chamber gas injection. At the first postoperative month, the BCVA was 20/25. The corneal cap adhered closely to the stroma, the surface became smooth.ConclusionsThis case illustrates that any corneal perforation following lamellar surgery, including SMILE, may lead to IFS. It is crucial to consider the depth of corneal perforation, and intraoperative optical coherence tomography (iOCT) plays a unique role in the repair procedure.

Clinical significance of signal shadowing during intraoperative optical coherence tomography-assisted vitreoretinal surgery

This study aimed to analyze the clinical significance of signal shadowing during intraoperative optical coherence tomography (iOCT)-assisted vitreoretinal surgery caused by vitreoretinal instruments, tissue dyes, and vitreous substitutes, and to objectively quantify its impact on iOCT imaging. This is a retrospective observational study of postoperative image analysis from one hundred seventeen (117) patients who underwent iOCT-assisted vitrectomy. The image data were divided into three groups: vitreoretinal instruments, tissue dyes, and vitreous substitutes. The data was then processed using graphic software to measure the grade of picture quality distortion and compared to paired image controls without clinically perceptive interference, then analyzed statistically. The intraocular portion of all studied vitreoretinal instruments caused a high average gray level interference compared to controls ranging from 32 to 68% reduction, obscuring the area of interest significantly. The tips of the instruments produced low-grade shadowing, allowing the underlying tissue to be distinguished. The analyzed dyes demonstrated a wide interference range: ICG (− 75.12%), and triamcinolone (− 26.13%) showed dose-dependent high shadowing, while VITREODYNE™ (49.3%) and brilliant blue G (14.06%) exhibited no perceived distortions whilst increasing average gray levels. All analyzed vitreous substitutes (air, SF6, C3F8, PFCL, and silicone oil) showed an insignificant shadowing effect on iOCT. Certain dyes and vitreous substitutes produce a negligible shadowing effect compared to controls and other dyes, providing an advantage during real-time iOCT imaging. All analyzed vitreoretinal instruments showed a significant interference that should prompt the development of new imaging techniques or the implementation of materials with low-grade interference to overcome a clinically relevant shadowing effect on iOCT, maximizing the technology’s visual accuracy and surgical diagnostic aid proficiency.

INTRAOPERATIVE OPTICAL COHERENCE TOMOGRAPHY OBSERVATION WITH PERFLUOROCARBON TAMPONADE FOR SUBRETINAL MEMBRANES IN PROLIFERATIVE VITREOUS RETINOPATHY.

To report the efficacy of intraoperative optical coherence tomography in locating proliferative membranes or strands subretinally or preretinally during pars plana vitrectomy for proliferative vitreoretinopathy or old rhegmatogenous retinal detachment. After removing the vitreous and apparent epiretinal membranes, vitreous fluid was exchanged for perfluorocarbon. Lesions of the retinal folds or persistently detached retinas, suspected to be subretinal membrane lesions, were examined using intraoperative optical coherence tomography in three eyes with proliferative vitreoretinopathy. Intraoperative optical coherence tomography showed subretinal or preretinal structures in all three patients. A subretinal structure with underlying fluid was removed through an intentional hole in a patient. In another patient, a subretinal structure without underlying fluid was not removed. In the remaining patient, the preretinal membranes detected with intraoperative optical coherence tomography could be peeled successfully. Intraoperative optical coherence tomography examination with perfluorocarbon tamponade effectively identified the correct location of proliferative membranes or strands, namely, preretinal or subretinal. This imaging technique helps surgeons determine whether an intentional hole should be made to remove the subretinal structure during vitrectomy. Intraoperative optical coherence tomography, combined with perfluorocarbon tamponade, leads to safer and more effective surgery for proliferative vitreoretinopathy.

Cataract due to iatrogenic lens trauma during an intravitreal injection-imaging using (intraoperative) optical coherence tomography

Cataract due to iatrogenic lens trauma during an intravitreal injection-imaging using (intraoperative) optical coherence tomography

Microscope‐integrated intraoperative OCT in ophthalmological examination of pediatric patients under anesthesia: 3 cases

Introduction: The examination of certain patients in con‐ sultation, due to their young age, lack of collaboration or associated pathologies can be very complicated or insuffi‐ cient. In cases of suspected diagnosis, an examination under sedation in the operating room is necessary. Classic tests such as sciascopy, renography, biometry or keratometry are very useful, however, microscope integrated intraoperative optical coherence tomography allows examining structures that are easily evaluable in clinical routine but not in this type of examination with sedation. Case report: We report three cases of pediatric patients, examined under sedation. In these cases, intraoperative Optical Coherence Tomography (OCT) has been essential to reach the diagnosis. Conclusion: Intraoperative OCT is very useful as part of the pediatric examination under sedation. It allows the eval‐ uation of structures and issues that could not be explored under their appearance and therefore, it helps to diagnose more precisely.

Artificial Intelligence, Digital Imaging, and Robotics Technologies for Surgical Vitreoretinal Diseases

ObjectiveTo review recent technological advancement in imaging, surgical visualization, robotics technology and the use of artificial intelligence in surgical vitreoretinal (VR) diseases. BackgroundTechnological advancements in imaging enhance both pre-operative and intra-operative management of surgical VR diseases. Widefield imaging in fundal photography and optical coherence tomography (OCT) can improve assessment of peripheral retinal disorders like retinal detachments, degeneration, and tumors. OCT angiography provides a rapid and non-invasive imaging of the retinal and choroidal vasculature. Surgical visualization has also improved with intraoperative OCT providing a detailed real-time assessment of retinal layers to guide surgical decisions. Heads-up display and head-mounted display utilize three-dimensional technology to provide surgeons with enhanced visual guidance and improved ergonomics during surgery. Intraocular robotics technology allows for greater surgical precision and is shown to be useful in retinal vein cannulation and subretinal drug delivery. In addition, deep learning techniques leverages on diverse data including widefield retinal photography and OCT for better predictive accuracy in classification, segmentation, and prognostication of many surgical VR diseases. ConclusionThis review article summarized the latest updates in these areas and highlights the importance of continuous innovation and improvement in technology within the field. These advancements have the potential to reshape management of surgical VR diseases in the very near future and to ultimately improve patient care.

Intraoperative optical coherence tomography-guided transconjunctival bleb suturing - A minimally invasive technique for managing overfiltering bleb.

With the recent advancement in technologies, real-time integrated intraoperative optical coherence tomography (iOCT) microscopes are available, which facilitates surgical precision and also reduces the risk of complications. Two glaucoma patients with advanced glaucomatous optic neuropathy, who underwent uneventful trabeculectomy with 0.02% mitomycin C, developed persistent hypotony postoperatively till 4-6 weeks. On clinical examination, visual acuity was 1/60 with low intraocular pressure (IOP) of 4 mmHg. Elevated, overfiltering bleb was seen on slit-lamp examination, along with hypotonous maculopathy. Anterior segment optical coherence tomography (AS-OCT) showed multiple large hyporeflective fluid spaces suggestive of overfiltering bleb. Considering the risk of choroidal detachment and further deterioration of vision, iOCT-guided transconjunctival bleb suturing was planned. iOCT helped to identify the exact location of scleral flap, and transconjunctival suturing was done with successful outcomes in terms of improved IOP and visual acuity.

Surgical outcomes of petalloid multilayered inverted internal limiting membrane flaps in extra-large macular holes.

To analyze the surgical outcomes of petalloid multilayered inverted internal limiting flap using perfluorocarbon liquid (PFCL) in extra-large macular holes (MHs) (minimum linear diameter >550 µm and basal diameter [BD] >1000 µm). This was a prospective interventional series of 103 eyes of 99 patients with extra-large MHs which were treated with 25-gauge pars plana vitrectomy, petalloid multilayered inverted internal limiting membrane flaps under PFCL and 15% perfluoropropane (C3F8) gas tamponade. Intraoperative optical coherence tomography (i-OCT) was used to confirm correct positioning of flaps. Follow-up was at 1 week, 1 month, and 3 months postoperatively. Mean age of patients was 58.282 ± 16.3 years. Mean preoperative best corrected visual acuity (BCVA) was logarithm of minimum angle of resolution (logMAR) 1.206 ± 0.384, and the value at the third month was logMAR 0.793 ± 0.337. Mean minimum linear diameter (MLD) was 711.96 ± 270.744 µm. MLD ranged from 557µm (minimum MLD) to 2657 µm (maximum MLD). Mean BD was 1301.165 ± 425.914 µm. Type 1 closure was seen in 92.2% eyes, 5.8% eyes had type 2 closure, and 1.9% eyes had type 3 closure. Eyes with both type 1 closure (P = 0.001) and type 2 closure (P = 0.009) showed a significant improvement in BCVA postoperatively at 3 months. Petalloid multilayered inverted internal limiting membrane flap under PFCL technique with adjunctive use of i-OCT showed improved morphological and functional outcomes in the treatment of extra-large MHs. We present here a large series of extra-large MHs, in which a novel technique of petalloid multilayered inverted ILM flaps was used.

Scleral Suture Intraocular Lens Fixation Under Microscope-Intraoperative Optical Coherence Tomography.

The aim of this study was to evaluate the accessibility and potential value of intraoperative optical coherence tomography (iOCT) during scleral suture intraocular lens (IOL) fixation. This was a prospective cohort study in the Department of Ophthalmology, Eye and ENT Hospital, Fudan University, China. Seven eyes with insufficient capsular support and undergoing two-point scleral suture IOL fixation were included. The potential value of iOCT was evaluated, as well as the safety and efficacy of the surgery. Seven eyes were included. With a tailor-made iOCT, the structure of the anterior segment could be clearly visualized during the surgery. Intraoperatively, iOCT helped locate the proper place for fixation and access the position of the IOL. After an average 4.43-month follow-up, the spherical equivalent changed significantly ( P < 0.001), but the intraocular pressure, best-corrected visual acuity, and endothelial cell density remained unchanged ( P > 0.05). The IOL was well-centered with a horizontal and a vertical tilt of 0.74 ± 0.60° and 1.13 ± 0.65°, and decentration of 0.28 ± 0.12 mm and 0.30 ± 0.13 mm. The estimated IOL-induced astigmatism was -0.11 diopters (D) ± 0.46 D. Real-time high-resolution images of the anterior segment acquired by the iOCT helped the surgeon to achieve satisfactory results in scleral suture IOL fixation.

Identification and Management of a Central Type 2 Big Bubble in Deep Anterior Lamellar Keratoplasty

Purpose: The purpose of this study was to document a case of central type 2 bubble formation during deep anterior lamellar keratoplasty and discuss its intraoperative management. Methods: A rare case of central type 2 bubble formation with no peripheral extension beyond the trephination mark was documented with operative video and concurrent intraoperative optical coherence tomography imaging. Results: The type 2 bubble was decompressed with a needle intraoperatively, and deep anterior lamellar keratoplasty was successfully performed without perforation of Descemet membrane. Conclusions: Identifying formation of a type 2 bubble during deep anterior lamellar keratoplasty is crucial in avoiding perforation of Descemet membrane. This case shows that the behavior of type 2 bubbles can be different than what has been widely reported. It is hoped that this will aid the surgeon in identifying a type 2 bubble and in properly managing it intraoperatively.

Comparison of three fundus inspection methods during phacoemulsification in diabetic white cataract.

To investigate whether Wild Field Imaging System (WFIS SW-8000), 25G endoilluminator, and intraoperative optical coherence tomography (iOCT) can perform real-time screening and diagnosing in patients with suspicious diabetic retinopathy (DR) during phacoemulsification, especially in cases of white cataract. A cross-sectional study was carried out. A total of 204 dense diabetic cataractous eyes of 204 patients with suspected DR treated from April 2020 to March 2021 were included. Phacoemulsification combined with intraocular lens implantation was performed. Following the removal of the lens opacity, the 25G endo-illuminator, fundus photography, and iOCT were performed successively. Optical coherence tomography (OCT) and/or fundus fluorescein angiography (FFA) were used to verify the fundus findings postoperatively. Intraoperative and postoperative results were compared to verify the accuracy of intraoperative diagnosis in each group. Intraoperative and postoperative examinations revealed 58 and 62 eyes with DR, respectively (positive rate, 28.43% and 30.39%, respectively). During the phacoemulsification, WFIS SW-8000 detected 44 eyes with DR (the detection rate, 70.97%); 25G endo-illuminator found 56 eyes with DR (the detection rate, 90.32%); iOCT found 46 eyes with DR (the detection rate, 74.19%); and 58 eyes with DR were found by combining the three methods (the detection rate, 93.55%). There were statistically significant differences in the diagnostic sensitivity for DR among the methods (χ2=16.36, P=0.001). WFIS SW-8000, 25G endo-illuminator, iOCT, and especially their combination can be used to inspect the fundus and detect DR intraoperatively; they are helpful for the timely diagnosis and treatment of DR in patients with dense cataract.

Descemet Membrane Endothelial Keratoplasty in Corneal Endothelial Decompensation After a Forceps-Induced Corneal Birth Injury: Case Series and Technique

Purpose: The aim of this study was to describe the efficacy of Descemet membrane endothelial keratoplasty (DMEK) in patients with corneal endothelial decompensation secondary to a forceps-induced corneal birth injury. Methods: This was a retrospective, noncomparative, interventional case series. Four eyes of 4 patients (1 female and 3 males; mean age, 64.0 ± 4.7 years) with corneal endothelial decompensation due to forceps-induced corneal birth injury were included. DMEK was performed in all cases, using a combined technique, including the use of intraoperative optical coherence tomography, vital staining of Descemet membrane of both host and donor, removal of scarred Descemet membrane with side-port forceps and vitreous cutter to smoothen the posterior corneal surface, epithelial peeling, and illumination for visualization. The examination included preoperative and postoperative ophthalmologic examinations: best-corrected visual acuity (converted to logarithm of the minimum angle of resolution [logMAR]), intraocular pressure, endothelial cell density (ECD), and central corneal thickness. Results: No postoperative complications were noted, and corneal transparency was maintained during follow-up (mean follow-up period, 32.0 ± 27.0 months; range, 3–71 months). The mean best-corrected visual acuity was 0.52 ± 0.35 logMAR preoperatively and 0.15 ± 0.09 logMAR at the last visit. The mean postoperative ECD was 1632 ± 631 cells/mm2 (mean ECD at baseline, 3167 cells/mm2). Central corneal thickness decreased from 640 ± 67 μm preoperatively to 576 ± 58 μm postoperatively. Conclusions: This study suggests that DMEK can be performed uneventfully in eyes with a forceps-induced corneal birth injury. The combination of surgical techniques may be an effective approach for DMEK.

Cataract Surgery Combined with Diabetic Vitrectomy and the Use of Intraoperative Optical Coherence Tomography

The cataract develops 2-5 times higher in patients with Diabetes Mellitus (DM) than in the normal population. With the advances in modern surgical equipment and surgical techniques, cataract surgery combined with vitrectomy has become increasingly common among vitreoretinal surgeons. Cataract surgery combined with vitrectomy has its own difficulties. In addition to these difficulties, there are specific situations that should be considered in vitrectomy combined with cataract surgery in patients with DM. Optical Coherence Tomography(OCT) is an imaging method that provides high-resolution sections of ocular tissues. OCT devices integrated into the operating microscope are systems that allow real-time images to be taken during surgery. In this review, vitrectomy combined with cataract surgery and the use of intraoperative OCT in patients with diabetic retinopathy is discussed.

Application of intraoperative optical coherence tomography in deep lamellar keratoplasty

Objective: To evaluate the clinical application value of intraoperative optical coherence tomography (iOCT) in deep anterior lamellar keratoplasty (DALK) using the big-bubble technique to bare Descemet's membrane. Methods: Retrospective case series. Clinical data of 92 patients (92 eyes) with monocular stromal corneal diseases who underwent big-bubble DALK in the Eye Hospital of Shandong First Medical University from January 2020 to August 2021 were collected. There were 53 males and 39 females. The average age was (53.2±16.0) years old. All patients underwent iOCT scanning to determine the location and depth of the injection needle after initial removal of the corneal lesion, to observe the integrity of the recipient bed, Descemet's membrane, after complete lesion removal, and to observe the adhesion between the corneal graft and the recipient bed and check folds on the recipient bed after suturing of the corneal graft. The intraoperative perforation of Descemet's membrane, postoperative thickness of the cornea and the recipient bed, visual acuity, and corneal astigmatism were recorded. Results: By iOCT, the thickness of the recipient bed was found to be about 1/2 of the corneal thickness and relatively uniform in all directions in 62 eyes (67.4%), so the sterile air was injected from the center of the recipient bed to separate it from the stromal layer. In 30 eyes (32.6%) with an uneven thickness of the recipient bed, the sterile air was injected from the paracentral area of the recipient bed. Under the guidance of iOCT scanning, 89 eyes (96.7%) did not experience any perforation of Descemet's membrane during surgery. The Descemet's membrane folds in the central 5-mm area of the recipient bed was observed and flattened in 20 eyes with the assistance of iOCT scanning. The postoperative corneal thickness was (578.95±108.26) μm, and the recipient bed thickness was (36.06±23.11) μm. The best corrected visual acuity of all patients at 6 months after surgery was 0.57±0.25 logMAR, which was significantly better than that before surgery (1.61±1.27 logMAR; P<0.001). The average corneal astigmatism at 6 months after surgery was (2.72±2.44) diopters. Conclusions: The application of iOCT scanning in DALK surgery assisted by the big-bubble method can provide safe guidance for surgeons to adopt correct surgical procedures, decrease the risk of Descemet's membrane perforation, reduce the recipient bed folds, and facilitate corneal interlayer adhesion, thereby improving the visual prognosis.