Second harmonic generation microscopy of electromechanical reshaping on corneal collagen.

Refractive errors remain a global health concern, as a large proportion of the world's population is myopic. Current ablative approaches are costly, not without risks, and not all patients are candidates for these procedures. Electromechanical reshaping (EMR) has been explored as a viable cost-effective modality to directly shape tissues, including cartilage. In this study, stromal collagen structure and fibril orientation was examined before and after EMR with second-harmonic generation microscopy (SHG), a nonlinear multiphoton imaging method that has previously been used to study native corneal collagen with high spatial resolution. EMR, using a milled metal contact lens and potentiostat, was performed on the corneas of five extracted rabbit globes. SHG was performed using a confocal microscopy system and all images underwent collagen fibril orientation analysis. The collagen SHG signal in controls is uniform and is similarly seen in samples treated with pulsed potential, while continuous EMR specimens have reduced, nonhomogeneous signal. Collagen fibril orientation in native tissue demonstrates a broad distribution with suggestion of another peak evolving, while with EMR treated eyes a bimodal characteristic becomes readily evident. Pulsed EMR may be a means to correct refractive errors, as when comparing its SHG signal to negative control, preservation of collagen structures with little to no damage is observed. From collagen fiber orientation analysis, it can be inferred that simple DC application alters the structure of collagen. Future studies will involve histological assessment of these layers and multi-modal imaging analysis of dosimetry.

Costal Cartilage Considerations: Novel Use of Handheld Ultrasound Device in Rhinoplasty.

Handheld ultrasound devices can be used in revision rhinoplasty to evaluate the calcification of costal rib cartilage that is to be harvested for grafting. This article provides instructions on how to perform this technique. Laryngoscope, 134:651-653, 2024.

Impact of Tissue Handling and Size Modification on Septal Chondrocyte Viability.

INTRODUCTION: The physical modification of cartilage grafts during rhinoplasty risks chondrocyte death at the margins where the tissue is cut. This study compares chondrocyte viability between diced, scaled, and pate samples in human models, and further computes percent chondrocyte viability as a function of sequential dicing size in a computational model. METHODS: Septal cartilage from 11 individuals was prepared as follows: diced (1 mm cubic), scaled (shaved to <1 mm thickness ~ translucent), pate (0.02 g of scraped cartilage surface), positive control (2 × 2 mm diced), and negative control (2 × 2 mm diced soaked in 70% EtOH). Viability analysis was performed using Live/Dead assay™ and confocal microscopy. Numerical simulation of cartilage dicing in 0.05 mm increments was performed using MATLAB assuming 250 chondrocytes/mm3 with each average chondrocyte size of 65 µm2. RESULTS: Chondrocyte viability was similar between 1 mm diced cartilage, scaled cartilage, and positive control samples (p > 0.05). Conversely, pate samples had significantly less viability compared to positive controls, diced samples, and scaled samples (all p < 0.01 after Bonferroni correction). Pate samples had similar chondrocyte viability compared to negative controls (p = 0.36). On computational modeling, cartilage viability decreased to 50% as the diced sample was cut from 1 mm edge length to 0.7-0.8 mm. Similarly, cartilage viability decreased to 26% at 0.55-0.65 mm, 11% at 0.4-0.5 mm, and <5% at <0.4 mm edge length. CONCLUSION: Modifying septal cartilage grafts into 1 mm diced or scaled samples maintains ideal chondrocyte viability whereas pate preparations result in significant chondrocyte death. According to computational analysis, chondrocyte viability sharply decreases as the cartilage is diced below 0.7-0.8 mm. LEVEL OF EVIDENCE: N/A Laryngoscope, 2024.

Prognostic Utility of Tumor Stage versus American Thyroid Association Risk Class in Thyroid Cancer.

OBJECTIVE: To evaluate the prognostic strengths of American Joint Committee on Cancer (AJCC) staging and American Thyroid Association (ATA) risk classification in well-differentiated thyroid cancer (DTC), and their implications in guiding medical decision-making and epidemiological study designs. METHODS: The 2004-2017 National Cancer Database was queried for DTC patients. Cox proportional hazards (CPH) and Kaplan-Meier analyses modeled patient mortality and overall survival, respectively. Each CPH model was evaluated by its concordance index, measure of explained randomness (MER), Akaike information criterion (AIC), and area under receiver operating characteristic curve (AUC). RESULTS: Overall, 134,226 patients were analyzed, with an average age of 48.1 ± 15.1 years (76.9% female). Univariate CPH models using AJCC staging demonstrated higher concordance indices, MERs, and AUCs than those using ATA risk classification (all p < 0.001). Multivariable CPH models using AJCC staging demonstrated higher concordance indices (p = 0.049), MERs (p = 0.046), and AUCs (p = 0.002) than those using ATA risk classification. The AICs of multivariable AJCC staging and ATA risk models were 7.564 × 104 and 7.603 × 104 , respectively. AJCC stage I tumors were associated with greater overall survival than those classified as ATA low risk, whereas AJCC stages II-III and stage IV tumors demonstrated worse survival than ATA intermediate- and high-risk tumors, respectively (all p < 0.001). CONCLUSION: AJCC staging may be a more predictive system for patient survival than ATA risk. The prognostic utility of these two systems converges when additional demographic and clinical factors are considered. AJCC staging was found to classify patients across a wider range of survival patterns than the ATA risk stratification system. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:205-211, 2023.

Electromechanical Cornea Reshaping for Refractive Vision Therapy.

The corneal stroma consists of orthogonally stacked collagen-fibril lamellae that determine the shape of the cornea and provide most of the refractive power of the eye. We have applied electromechanical reshaping (EMR), an electrochemical platform for remodeling cartilage and other semirigid tissues, to change the curvature of the cornea as a potential procedure for nonsurgical vision correction. EMR relies on short electrochemical pulses to electrolyze water, with subsequent diffusion of protons into the extracellular matrix of collagenous tissues; protonation of immobilized anions within this matrix disrupts the ionic-bonding network, leaving the tissue transiently responsive to mechanical remodeling. Re-equilibration to physiological pH restores the ionic matrix, resulting in persistent shape change of the tissue. Using ex vivo rabbit eyes, we demonstrate here the controlled change of corneal curvature over a wide range of refractive powers with no loss of optical transparency. Optical coherence tomography (OCT), combined with second-harmonic generation (SHG) and confocal microscopy, establish that EMR enables extremely fine control of corneal contouring while maintaining the underlying macromolecular collagen structure and stromal cellular viability, positioning electrochemical vision therapy as a potentially simple and ultralow-cost modality for correcting routine refractive errors.

Potential-Driven Electrochemical Clearing of Ex Vivo Alkaline Corneal Injuries.

Purpose: Corneal chemical injuries (CCI) obscure vision by opacifying the cornea; however, current treatments may not fully restore clarity. Here, we investigated potential-driven electrochemical treatment (P-ECT) to restore clarity after alkaline-based CCI in ex vivo rabbit corneas and examined collagen fiber orientation changes using second harmonic generation (SHG). Methods: NaOH was applied to the corneas of intact New Zealand white rabbit globes. P-ECT was performed on the opacified cornea while optical coherence tomography (OCT) imaging (∼35 frames per second) was simultaneously performed. SHG imaging evaluated collagen fiber structure before NaOH application and after P-ECT. Irrigation with water served as a control. Results: P-ECT restored local optical clarity after NaOH exposure. OCT imaging shows both progression of NaOH injury and the restoration of clarity in real time. Analysis of SHG z-stack images show that collagen fibril orientation is similar between control, NaOH-damaged, and post-P-ECT corneas. NaOH-injured corneas flushed with water (15 minutes) show no restoration of clarity. Conclusions: P-ECT may be a means to correct alkaline CCI. Collagen fibril orientation does not change after NaOH exposure or P-ECT, suggesting that no irreversible matrix level fiber changes occur. Further studies are required to determine the mechanism for corneal clearing and to ascertain the optimal electrical dosimetry parameters and electrode designs. Translational Relevance: Our findings suggest that P-ECT is a potentially effective, low-cost treatment for alkaline CCI.

Outcomes of Concurrent Functional Endoscopic Sinus Surgery and Rhinoplasty: A Meta-analysis.

INTRODUCTION: Chronic rhinosinusitis (CRS) and functional nasal airway obstruction are common but distinct medical problems which affect quality of life. In certain instances, patients often benefit from concomitant functional septorhinoplasty, or elect for cosmetic rhinoplasty, in addition to functional endoscopic sinus surgery (FESS) and prefer combining procedures. Determining outcomes of combined surgery is important when discussing risks and benefits with patients. METHODS: A thorough literature search of articles published in PubMed, Ovid MEDLINE, and Cochrane databases. Patients were categorized as either having FESS or rhinoplasty alone or combined. Binary random-effects models were applied to calculate odds ratios (ORs) for outcomes including complications, recurrence, and satisfaction. RESULTS: Of the 55 screened articles, 6 were included in the analysis, and of these, 6 (405 patients), 2 (90 patients), 4 (290 patients), and 3 (190 patients) provided data for postoperative complications, recurrence of CRS symptoms, revision rates, and patient satisfaction, respectively. Major complications were observed in 11 (5.8%) total combined cases, 0 (0%) FESS cases, and 6 (3.5%) rhinoplasty cases with no statistical difference between combined cases and rhinoplasties (OR 1.37, 95% CI 0.45-4.16, p = 0.58). Recurrence of CRS symptoms was noted in 35.6% combined cases and 28.9% FESS cases (OR 1.42, 95% CI 0.55-3.64, p = 0.47). There was no observed difference in revision rates between combined and isolated rhinoplasties (OR 1.00, 95% CI 0.43-2.32, p = 1). Lastly, 91.6% of patients were satisfied with results of combined cases compared to 87.4% of patients in standalone cases (OR 1.57, 95% CI 0.61-4.03, p = 0.35). CONCLUSION: Aggregate evidence demonstrates similar risk in complication rates in combined surgical cases compared to stand-alone rhinoplasty. There appears to be no significant difference in recurrence of symptoms, revision rates or patient satisfaction.

Video Standards for Rhinoplasty Education: A Review and Recommended Guidelines.

Importance: Intraoperative videography is widely used to record rhinoplasty procedures, yet little is known about the optimal surgical vantage points at critical procedural steps. Objective: To assess commonly used camera angles in public and proprietary intraoperative rhinoplasty videos and discuss approaches to obtaining these viewing angles. Design: Public and propriety rhinoplasty videos were reviewed and categorized based on procedure type, specific area(s) of focus, and camera angles utilized at a series of critical operative steps. The most commonly used camera angles were recorded and assessed based on surgical field visualization and the authors' personal recording experiences. Results: Of the 114 videos that met inclusion criteria, 49 were full-length open rhinoplasty procedures, 20 full-length endonasal rhinoplasty procedures, 17 tip techniques, 8 opening techniques, 7 fashioning grafts, 7 osteotomies, and 6 cartilage harvests. With respective to footage acquisition, the upward camera angle was most frequently used for recording, and endoscopic view was least frequently used. Conclusions and Relevance: These findings demonstrate that there is extensive variability in camera angles between surgical films. Moreover, many of these camera angles are insufficient due to obstruction by surgical staff, inability to visualize deep structures, and difficulty capturing the three-dimensional nasal framework. A guide indicating the best viewing angles for different aspects of the procedure would be useful to optimize educational videos.