Acoustic Radiation Force Optical Coherence Elastography of the Crystalline Lens: Safety.

Purpose: To assess the safety of acoustic radiation force optical coherence elastography in the crystalline lens in situ.

Methods: Acoustic radiation force (ARF) produced by an immersion single-element ultrasound transducer (nominal frequency = 3.5 MHz) was characterized using a needle hydrophone and used for optical coherence elastography (OCE) of the crystalline lens.

Chirp excitation for natural frequency optical coherence elastography.

Optical coherence elastography (OCE) has recently been used to characterize the natural frequencies of delicate tissues (e.g., the human cornea) with sub-micron tissue oscillation magnitudes.

Dual-channel air-pulse optical coherence elastography for frequency-response analysis.

Microliter air-pulse optical coherence elastography (OCE) has recently been proposed for the characterization of soft-tissue biomechanics using transient, sub-nanometer to micrometer-scale natural frequency oscillations. However, previous studies have not been able to provide real-time air-pulse monitoring during OCE natural frequency measurement, which could lead to inaccurate measurement results due to the unknown excitation spectrum. To address this issue, we introduce a dual-channel air-pulse OCE method, with one channel stimulating the sample and the other being simultaneously measured with a pressure sensor.

Corneal Surface Wave Propagation Associated with Intraocular Pressures: OCT Elastography Assessment in a Simplified Eye Model.

Assessing corneal biomechanics in vivo has long been a challenge in the field of ophthalmology. Despite recent advances in optical coherence tomography (OCT)-based elastography (OCE) methods, controversy remains regarding the effect of intraocular pressure (IOP) on mechanical wave propagation speed in the cornea. This could be attributed to the complexity of corneal biomechanics and the difficulties associated with conducting in vivo corneal shear-wave OCE measurements.

corneal elastography: A topical review of challenges and opportunities.

Clinical measurement of corneal biomechanics can aid in the early diagnosis, progression tracking, and treatment evaluation of ocular diseases. Over the past two decades, interdisciplinary collaborations between investigators in optical engineering, analytical biomechanical modeling, and clinical research has expanded our knowledge of corneal biomechanics. These advances have led to innovations in testing methods (, and recently, in vivo) across multiple spatial and strain scales.

assessment of corneal biomechanics under a localized cross-linking treatment using confocal air-coupled optical coherence elastography.

The localized application of the riboflavin/UV-A collagen cross-linking (UV-CXL) corneal treatment has been proposed to concentrate the stiffening process only in the compromised regions of the cornea by limiting the epithelium removal and irradiation area. However, current clinical screening devices dedicated to measuring corneal biomechanics cannot provide maps nor spatial-dependent changes of elasticity in corneas when treated locally with UV-CXL. In this study, we leverage our previously reported confocal air-coupled ultrasonic optical coherence elastography (ACUS-OCE) probe to study local changes of corneal elasticity in three cases: untreated, half-CXL-treated, and full-CXL-treated rabbit corneas (n = 8).

Micron-scale hysteresis measurement using dynamic optical coherence elastography.

We present a novel optical coherence elastography (OCE) method to characterize mechanical hysteresis of soft tissues based on transient (milliseconds), low-pressure (<20 Pa) non-contact microliter air-pulse stimulation and micrometer-scale sample displacements. The energy dissipation rate (sample hysteresis) was quantified for soft-tissue phantoms (0.8% to 2.

Spatial Assessment of Heterogeneous Tissue Natural Frequency Using Micro-Force Optical Coherence Elastography.

Analysis of corneal tissue natural frequency was recently proposed as a biomarker for corneal biomechanics and has been performed using high-resolution optical coherence tomography (OCT)-based elastography (OCE). However, it remains unknown whether natural frequency analysis can resolve local variations in tissue structure. We measured heterogeneous samples to evaluate the correspondence between natural frequency distributions and regional structural variations.