Electromechanical reshaping (EMR) has the potential to change corneal shape to correct refractive errors without altering the mechanical properties of the cornea. Using acoustic radiation force (ARF) to stimulate the cornea of ex vivo New Zealand white rabbit globes and optical coherence elastography (OCE) to detect corneal response, the cornea’s elasticity was quantitatively determined pre- and post-EMR treatment. In addition, an optical coherence tomography (OCT) system was used to determine changes in corneal curvature. Ultimately, EMR treatment induced a shape change in the cornea and the elasticity of the cornea was similar before and after EMR treatment, indicating minimal damage.
We present an early release of our study utilizing a fiber-based Optical Coherence Tomography (OCT) probe to acquire 3D images of the airway in sleep apnea patients. The probe, with a 1.3mm diameter, navigates from the nasal cavity to the vocal cords while rotating within a transparent protective sheath. Long-range OCT imaging (2-30mm) enables comprehensive airway visualization. Our approach facilitates airflow dynamic analysis, aiding in the identification of critical regions prone to collapse during sleep. This non-invasive technique promises to revolutionize sleep apnea diagnostics and personalized treatment planning, offering substantial benefits to patient care.
Proper ciliary dynamics is vital for effective mucociliary transport, the primary defense mechanism for the upper respiratory tract. Abnormal cilia behavior could lead to chronic respiratory disease, making it essential to conduct more detailed studies. In this study we present a multimodality system, specifically using optical coherence tomography (OCT) and phase-resolved spectrally encoded interferometric microscopy (PR-SEIM). We have already shown that PR-SEIM is capable of measuring cilia beat frequency ex vivo. Although we were able to visually identify the ciliary motion in the nasal cavity of rabbits in vivo, due to its sensitivity to motion artifacts, it has been difficult to quantitatively analyze ciliary dynamics. To overcome this obstacle, we incorporated OCT along with a high-speed laser source to compensate for bulk motion. Ultimately, this system will provide a way to study ciliary dynamics in its natural environment, thus allowing more in-depth understanding of ciliary functions.
Past studies used the VCSEL OCTs to image neonatal upper airways. However, due to manufacturing difficulties, the optimal focal length of the probe for VCSEL OCTs has yet to be determined. To determine this, both animal tracheas (duck and rabbit) and in vivo intubated neonates' upper airways were imaged with different probe focal lengths. In this study, the optimal VCSEL OCT probe focal lengths were provided for better image quality.
Currently in the realm of medical diagnostics there is an abundance of data – more than can be analyzed by humans in a finite amount of time. Specifically in otolaryngology, there are numerous biophotonics imaging modalities used in a wide spectrum of disease processes from benign to malignant. Within the past decade, artificial intelligence (AI) has been an increasingly studied field as there is a need for accurate, expeditious, and automated data processing. However, application of AI in this field is still expanding. As AI can provide robust and automated processing, it can be integrated into the physicians’ toolbox.
In this study, Optical Coherence Tomography (OCT) was used to image the large upper airway in a rabbit model. U-net convolutional neural network (CNN) was used to automate the segmentation of large airway edema and tissue changes. Peak edema volume was reached at 30-minutes post-chlorine gas exposure, then down trended until the 6-hour timepoint. Herein, we show the streamlining of OCT imaging analysis status-post chlorine inhalation injury using CNNs.
Chemical injuries to the cornea account for 11 to 22% of all ocular injuries. Acidic injuries are commonly due to sulfuric, hydrochloric, hydrofluoric, and battery acids, while basic injuries are commonly due to sodium hydroxide, chlorine bleach, and ammonia products. We have previously studied potential-driven electrochemical clearing (P-ECC) for alkaline injuries. In this study, we investigated the use of P-ECC on both acidic and alkaline injuries to determine its effect on restoring corneal transparency. Optical coherence tomography (OCT) was performed before and after P-ECC to determine adequate corneal clearing. Severity of chemical injury was measured through second harmonic generation (SHG) imaging. HCl or NaOH was applied to the corneas of New Zealand white rabbit globes. P-ECC was performed on opacified cornea while OCT imaging was simultaneously performed to evaluate depth resolved clarity. SHG imaging evaluated the structure of collagen before HCl or NaOH application and after P-ECC. Irrigation with water served as positive control. Native rabbit corneas were used as a negative control group. P-ECC induced clearing in the rabbit cornea, shown through OCT. Clearing occurred in regions where the working electrode made contact with the cornea. SHG imaging showed restoration of collagen fibril signal in P-ECC treated corneas compared to control. P-ECC is a potentially effective therapy for clearing acidic and alkaline corneal injuries. However, more ex-vivo experiments are required to determine the specific parameter for optimal clearing. In-vivo experiments are necessary to determine its potential for clinical use.
Mucociliary clearance is an important physiological mechanism for clearing the upper airways. Previously, it has been shown that different disease processes and drugs affect ciliary beat frequency (CBF). Namely, epinephrine has been shown to accelerate CBF in various animal models. Additionally, phase contrast microscopy (PCM) and spectrally encoded interferometric microscopy (SEIM) have been used to image dynamic tissue of the upper airway. Herein, we explore the effects of epinephrine on human sinonasal mucosa through PCM and SEIM. Sinonasal mucosa was harvested from patients undergoing endoscopic sinus surgery (ESS). Tissue was imaged using PCM and SEIM, maintaining physiological temperature through the use of warmed HBSS and a heating plate. Videos were taken before addition of any drugs as baseline. Epinephrine was diluted to 1 mg/mL (1:1000) and 1mL of solution was introduced to the sinonasal mucosa. PCM and SEIM was performed after to determine effects of epinephrine on CBF. Data analysis was performed using MATLAB (Mathworks, Natick, Massachusetts). Human sinonasal mucosa, taken from various anatomic locations, showed CBF values on PCM and SEIM consistent with what has been shown in previous literature. Upon addition of epinephrine to sinonasal mucosa, a marked increase in CBF was observed in both PCM and SEIM. In conclusion, the addition of epinephrine to sinonasal mucosa increased ciliary beat frequency. This validates the use of SEIM for determining CBF in sinonasal tissues. Further studies include adding to our sample size to determine a more accurate magnitude of increase of CBF.
Mucociliary clearance is vital for preventing any foreign substances from entering the upper airway that can later develop into acute and/or chronic respiratory diseases. Therefore, it is essential to further advance our understanding of the mucociliary functions. Our lab has been able to make key developments in imaging cilia, specifically measuring cilia beat frequency, with phase-resolved Doppler optical coherence tomography. In this system, we have further developed the system by incorporating phase-resolved spectrally encoded interferometric microscopy (SIEM) system with an FDML laser with MHz sweep rate to image cilia with higher accuracy and to minimize motion artifacts. In addition, we have designed a compact handheld probe system with a GRIN lens for easier in vivo imaging. The development of this system will allow us to further investigate cilia dynamics and ultimately utilize the system for clinical applications.
Mucociliary clearance facilitated by healthy cilia beating is crucial to normal upper airway function. Phase-contrast microscopy (PCM) is the current golden standard for measuring ciliary beat frequency (CBF) and has limitations. With PCM, one cannot appreciate how CBF varies across the complex landscape of the nasal vault and sinus tissues. With Spectrally encoded interferometric microscopy (SEIM), en face imaging of cilia can be achieved, providing insight into the changes in CBF across tissue surfaces. This study aims to validate the use of SEIM to quantify ciliary beat frequency across ex vivo upper airway tissue.
Refractive errors commonly cause vision impairments; current treatments are temporary and/or involve side-effects. We performed electromechanical reshaping (EMR), a potential laser eye surgery alternative, to determine its effect on reshaping corneal curvature in ex vivo rabbit corneas. Optical coherence tomography (OCT) was performed to ensure corneal curvature change. Second harmonic generation (SHG) was used to determine if collagen damage occurred. After EMR, shape change was visualized with OCT while SHG indicated weaker collagen signals in certain regions. EMR is a potential treatment for refractive errors. However, more experiments are required to determine efficacy and potential for clinical application.
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