Identification of the Vibrational Optical Coherence Tomography Corneal Cellular Peak.

Purpose: Our team previously identified the presence of five corneal resonant frequency (RF) peaks in healthy volunteers using vibrational optical coherence tomography (VOCT). Prior studies have suggested that the ≤100 Hz RF peak represents the cellular element of tissue. The aim of this study was to confirm that this peak reflects the human corneal cellular component using VOCT and histological analysis. Methods: Two human research globes were obtained from the same donor, and VOCT measurements were collected from the full-thickness corneas. A microkeratome was then used to create serial-free corneal caps from each cornea, with VOCT performed on the residual stromal bed after each excision. All lamellar sections from both globes were sent for histological analysis to determine cellularity. Cell counts on the specimens were performed by two independent observers. Results: The average of the normalized ≤100 Hz peak values before lamellar sectioning was significantly higher than the average of this peak values after the first, second, and third cuts (P = 0.023), which was 33.9% less than before any cuts. The cell count values in the first slice were significantly higher than the average cell count values of the three deeper slices (P < 0.001), and the cell count dropped 84.4% after the first slice was removed. Conclusions: The findings of this study suggest that the ≤100 Hz corneal peak identified by VOCT corresponds to the cellular component of the cornea. Translational Relevance: This work furthers our understanding of the origin of the corneal ≤100 Hz peak identified using VOCT.

The risk of central nodal metastasis based on prognostic factors of the differentiated thyroid carcinoma: a systematic review and meta-analysis study.

BACKGROUND AND AIM: Despite improving the 10-year disease-free-survival, prophylactic central neck dissection (pCND) in differentiated thyroid carcinoma (DTC) should only be considered in patients with high risk factors for lymph node (LN) metastasis due to the increases in the risk of postoperative complications. Our aim was to identify the risk factors for central lymph node metastasis (CLNM) in DTC. METHOD: We searched PubMed, Scopus, Web of science, Cochrane library for eligible studies from inception to November 1, 2021 and a systematic review and meta-analysis were carried out to identify the risk factors for CLNM in DTC. RESULTS: We included 41 studies with total of 27,741 patients in this study. The pooled results in this meta-analysis showed that these risk factors were significantly associated with CLNM: age < 45 years (odds ratio (OR) 1.64, 95% confidence interval (CI) 1.34-1.99, p < 0.00001), male sex (OR 1.73, 95% CI 1.54-1.93, p < 0.00001), multifocality (OR 1.87, 95% CI 1.59-2.19, p < 0.00001), bilateral disease (OR 1.43, 95% CI 1.15-1.78, p < 0.001), capsular invasion (OR 1.67, 95% CI 1.10-2.54, p < 0.02), lymphovascular invasion (OR 4.89, 95% CI 2.76-8.66, p < 0.00001) and extra-thyroidal extension (OR 2.43, 95% CI 1.97-3.00, p < 0.00001). In addition, young age (< 45 years), male sex, multifocality, and extra-thyroidal extension were significantly associated with large-volume CLNM in clinically N0 DTC patients. However, the presence of Hashimoto's thyroiditis was not a predictors of large-volume CLNM. CONCLUSION: Young age (< 45 years), male sex, bilateral disease, multifocality, capsular invasion, lymphovascular invasion and extra-thyroidal extension are significantly associated with CLNM and pCND would be expected to have a higher yield in patients with these risk factors.

In Vivo Determination of the Human Corneal Elastic Modulus Using Vibrational Optical Coherence Tomography.

Purpose: To determine the in vivo elastic modulus of the human cornea using vibrational optical coherence tomography (VOCT). Methods: Vibrational analysis coupled with optical coherence tomography (OCT) was used to obtain the resonant frequency (RF) and elastic modulus of corneal structural components. VOCT corneal thickness values were measured using OCT images and correlated with corneal thickness determined with Pentacam (Oculus, Wetzlar, Germany). Moduli were obtained at two locations: central cornea (CC) and inferior cornea (IC). Measurements were obtained with and without anesthetic eye drops to assess their effect on the modulus measurements. Results: VOCT thickness values correlated positively (R2 = 0.97) and linearly (y = 1.039x-16.89) with those of Pentacam. Five RF peaks (1-5) were present, although their presence was variable across eyes. The RF for peaks 1 to 5 in the CC and IC ranged from 73.5 ± 4.9 to 239 ± 3 Hz and 72.1 ± 6.3 to 238 ± 4 Hz, respectively. CC and IC moduli for peaks 1 to 5 ranged from 1.023 ± 0.104 to 6.87 ± 0.33 MPa and 0.98 ± 0.15 to 6.52 ± 0.79 MPa, respectively. Topical anesthesia did not significantly alter the modulus (P > 0.05 for all), except for peak 2 in the CC (P < 0.05). Conclusions: This pilot study demonstrates the utility of VOCT as an in vivo, noninvasive technology to measure the elastic modulus in human corneas. The structural origin of these moduli is hypothesized based on previous reports, and further analyses are necessary for confirmation. Translational Relevance: This work presents VOCT as a novel approach to assess the in vivo elastic modulus of the cornea, an indicator of corneal structural integrity and health.