Intraoperative optical coherence tomography in anterior segment surgery

Recent Advancements in Glaucoma Surgery-A Review

Surgery has long been an important treatment for limiting optic nerve damage and minimising visual loss in patients with glaucoma. Numerous improvements, modifications, and innovations in glaucoma surgery over recent decades have improved surgical safety, and have led to earlier and more frequent surgical intervention in glaucoma patients at risk of vision loss. This review summarises the latest advancements in trabeculectomy surgery, glaucoma drainage device (GDD) implantation, and minimally invasive glaucoma surgery (MIGS). A comprehensive search of MEDLINE, EMBASE, and CENTRAL databases, alongside subsequent hand searches-limited to the past 10 years for trabeculectomy and GDDs, and the past 5 years for MIGS-yielded 2283 results, 58 of which were included in the final review (8 trabeculectomy, 27 GDD, and 23 MIGS). Advancements in trabeculectomy are described in terms of adjunctive incisions, Tenon's layer management, and novel suturing techniques. Advancements in GDD implantation pertain to modifications of surgical techniques and devices, novel methods to deal with postoperative complications and surgical failure, and the invention of new GDDs. Finally, the popularity of MIGS has recently promoted modifications to current surgical techniques and the development of novel MIGS devices.

Swab Pressing vs Stromal Hydration to Prevent Incision Leakage and Transient Collapse of Anterior Chamber in Phacoemulsification: A Randomized Clinical Trial

Importance

During phacoemulsification, incision leakage and the subsequent anterior chamber collapse often occur after the withdrawal of the handpiece, which cannot be prevented by current sealing techniques. A new technique called swab pressing is proposed here to apply pressure with a cotton swab to seal the incision immediately, but efficacy remains unknown.

Objective

To determine if swab pressing is noninferior to stromal hydration, the current practice, in sealing incisions in phacoemulsification for age-related cataract.

Design, Setting, and Participants

This noninferiority randomized controlled clinical trial was conducted between February 2022 and September 2022 at the Zhongshan Ophthalmic Center, Guangzhou, China. Patients aged 60 to 90 years with age-related cataract were enrolled.

Interventions

Participants were randomly assigned (1:1) to receive swab pressing or stromal hydration. All surgeries were performed by a single experienced surgeon who was unmasked to the assignment.

Main Outcomes and Measures

The proportion of closed clear corneal incisions evaluated using intraoperative optical coherence tomography.

Results

A total of 126 eyes of 126 participants were randomized into the swab pressing group (63 [50%]) and stromal hydration group (63 [50%]). The mean (SD) age of participants was 69.2 (6.14) years and 70.1 (7.67) years in the pressing and stromal hydration groups, respectively. A total of 39 participants (61.9%) in the pressing group and 35 (55.6%) in the modified group were female. The proportion of closed incisions was 96.8% (61 of 63) in the swab pressing group and 93.7% (59 of 63) in the stromal hydration group. Noninferiority was met, as the lower 95% CI of -5.83 percentage points was greater than the prescribed noninferiority margin of -6.60 percentage points (difference, 3.17 percentage points; 95% CI, -5.83 to 12.18 percentage points). The rate of anterior chamber collapse (pressing: 0 of 63 vs stromal hydration: 35 of 63 [55.6%]; P < .001) was lower in the swab pressing group. There were no differences between the 2 groups in the proportion of closed incisions and central anterior chamber depth at postoperative hour 1 and day 1.

Conclusions and Relevance

In this study, swab pressing was noninferior to stromal hydration in sealing clear corneal incisions in phacoemulsification for age-related cataract. While this trial involved only 1 surgeon who was not masked to the interventions, the results suggest that swab pressing is feasible and further investigations would be warranted to determine if it prevents the intraoperative transient collapse of anterior chamber or affects visual acuity outcomes.

Trial Registration

ClinicalTrials.gov Identifier: NCT05242653.

Comparative study of optical coherence tomograph and histological images of eustachian tube nasopharyngeal region and adjacent structures in vivo and ex-vivo miniature pigs

OBJECTIVES

Optical Coherence Tomograph (OCT) imaging technology can be used to examine, in vivo, the human ET. At present, it is impossible to achieve the OCT scanning vivo and ex vivo in the same individual human body, or study the consistency between OCT images and histological images of the eustachian tube nasopharyngeal region and adjacent structures. The aim of this study was to determine the consistency between OCT images and histological sections in vivo and ex vivo in miniature pigs.

METHODS

OCT imaging was performed on five adult miniature pigs in vivo and ex vivo. The images of the eustachian tube OCT (ET-OCT), nasopharynx OCT (NP-OCT) and histological cross sections were further studied.

RESULTS

All five miniature pigs achieved the OCT scan successfully, acquiring ET-OCT and NP-OCT images in vivo and ex vivo on both sides. The acquired ET OCT images closely matched the histological images, revealing details of the cartilage, submucosa, glands, and mucosa. The lower segment of the ET wall mucosa had an abundance of glands and submucosal tissues, with more low-signal areas appearing in the ex vivo images. The NP-OCT images of the nasopharynx matched the details of the mucosa and submucosal tissues. The ex-vivo OCT images showed thicker mucosa and more scattered slightly lower signal areas compared to the vivo OCT images.

CONCLUSIONS

ET-OCT images and NP-OCT images matched the histological structure of eustachian tube nasopharyngeal region structures in miniature pigs both in vivo and ex vivo. OCT images may be sensitive to changes in edema and ischemia status. There is a great potential for morphological assessment of inflammation, edema, injure, mucus gland status.

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.

Research progress on the application of optical coherence tomography in the field of oncology

Optical coherence tomography (OCT) is a non-invasive imaging technique which has become the “gold standard” for diagnosis in the field of ophthalmology. However, in contrast to the eye, nontransparent tissues exhibit a high degree of optical scattering and absorption, resulting in a limited OCT imaging depth. And the progress made in the past decade in OCT technology have made it possible to image nontransparent tissues with high spatial resolution at large (up to 2mm) imaging depth. On the one hand, OCT can be used in a rapid, noninvasive way to detect diseased tissues, organs, blood vessels or glands. On the other hand, it can also identify the optical characteristics of suspicious parts in the early stage of the disease, which is of great significance for the early diagnosis of tumor diseases. Furthermore, OCT imaging has been explored for imaging tumor cells and their dynamics, and for the monitoring of tumor responses to treatments. This review summarizes the recent advances in the OCT area, which application in oncological diagnosis and treatment in different types: (1) superficial tumors:OCT could detect microscopic information on the skin’s surface at high resolution and has been demonstrated to help diagnose common skin cancers; (2) gastrointestinal tumors: OCT can be integrated into small probes and catheters to image the structure of the stomach wall, enabling the diagnosis and differentiation of gastrointestinal tumors and inflammation; (3) deep tumors: with the rapid development of OCT imaging technology, it has shown great potential in the diagnosis of deep tumors such in brain tumors, breast cancer, bladder cancer, and lung cancer.

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.

Applications of Optical Coherence Tomography in the Ocular Diagnosis: From the Tear Film to the Sclera

The latest technological developments have radically impacted the daily practice of ophthalmologists, thanks to the advent of novel diagnostic tools that facilitate an early diagnosis and allow a better management of ocular disorders [...]

Intraoperative OCT for the assessment of posterior capsular integrity in pediatric cataract surgery

PURPOSE

To study the morphology of the posterior lens cortex and posterior capsules (PCs) in pediatric patients with posterior lens opacities using intraoperative optical coherence tomography (iOCT).

SETTING

Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.

DESIGN

Prospective observational study.

METHODS

Pediatric patients with posterior lens opacities were imaged using iOCT during cataract surgery. The morphology of the posterior lens cortex and PC, along with the common patterns to indicate PC integrity, was assessed. Moreover, PC rent during surgery was observed.

RESULTS

A total of 62 eyes from 53 patients were included. The mean age of patients was 3.8 years. 4 morphological variants of posterior lens opacity were observed: type I (34/62 [54.8%]) with an intact PC; type II (20/62 [32.3%]) with an intact PC, which protruded into the anterior vitreous; type III (3/62 [4.8%]) with a deficient PC and an inability to delineate the PC; and type IV (5/62 [8.1%]) with dense opacity and an inability to characterize the posterior cortex and PC. Phacoemulsification could be performed in types I and II. In types III and IV, manual nucleus removal was performed instead of phacoemulsification. 3 cases (100%) of type III PC dehiscence developed during surgery, whereas no cases developed PC dehiscence of other types.

CONCLUSIONS

The morphology of the PC and posterior lens cortex in pediatric posterior lens opacities could be categorized, and PC integrity could be assessed using iOCT, which was useful to guide surgical strategies and increase safety in pre-existing PC dehiscence in pediatric cataract surgery.

Intraoperative optical coherence tomography-guided management of post-laser-assisted in situ keratomileusis epithelial ingrowth

We describe a modified technique of intraoperative optical coherence tomography (iOCT)-guided removal of post-laser-assisted in situ keratomileusis (LASIK) epithelial ingrowth with interface ethyl alcohol and mitomycin C application to prevent a recurrence. Epithelial ingrowth was visualized as hyperreflective deposits in the interface on iOCT, and the location and extent were noted at the beginning of the procedure. A simple dimple-down maneuver was performed to help identify the circumference of the LASIK flap. iOCT helped to delineate the flap edge and ensure dissection in the correct plane with complete removal of epithelial cell nests. Real-time visualization of the interface helped in on-table decision making regarding the extent of lifting the flap to encompass the entire region of hyperreflective epithelial ingrowth, as well as the need for additional interventions to ensure complete flap apposition at the end of surgery. All patients gained an uncorrected visual acuity of 20/20–20/25 with no recurrence.

Dimensions of the limbus-ciliary sulcus region by OCT and correlation study in a large population

PURPOSE

To assess the dimensions of the limbus-ciliary sulcus region measured by swept-source optical coherence tomography (SS-OCT) and conduct a correlation study in a large healthy population.

SETTING

Centro Internacional de Oftalmología Avanzada, Madrid, Spain.

DESIGN

Cross-sectional study.

METHODS

The dimensions of the limbus-ciliary sulcus region were measured in the temporal and nasal quadrants using a SS-OCT. The limbus-sulcus distance (LSD), the posterior iris line-ocular surface to limbus distance (PIOLD), and the angle-to-sulcus distance (ASD) were measured. These distances were then assessed for correlations with factors such as age, sex, refractive error, anterior chamber angle (ACA), ciliary muscle thickness (CMT), conjunctival-Tenon capsule thickness (CTT), and anterior scleral thickness (AST).

RESULTS

The mean age of the participants was 41.0 ± 18.2 years (range 5 to 86) and the mean refractive error -0.75 ± 3.3 diopters (range -10 to 7). The LSD could be measured in 93.2% of the participants (625 eyes out of 670 eyes), with a mean of 1.35 ± 0.12 mm (range 0.96 to 1.75) and 1.33 ± 0.12 mm (range 1.05 to 1.68) in the temporal and nasal quadrants, respectively, and a correlation of R = 0.616 (P < .001) between them. PIOLD measured 2.22 ± 0.31 mm (1.42 to 2.98), and ASD was 0.21 ± 0.05 mm (0.01 to 0.40). No correlation was observed between LSD with age, spherical error, sex, or ACA (P ≥ .247). However, LSD exhibited the highest correlation with AST (R = 0.466), followed by CTT (R = 0.309) and CMT (R = 0.259).

CONCLUSIONS

The SS-OCT allowed for an accurate in vivo measurement of the dimensions of the limbus-ciliary sulcus region.