Karol Karnowski

University of Western Australia | UWA · Optical and Biomedical Engineering (OBEL)

The field of visual and physiological optics is undergoing continuous significant advancements, driven by a deeper understanding of the human visual system and the development of cutting-edge optical technologies. This Roadmap, authored by leading experts, delves into critical areas such as corneal biomechanical properties, keratoconus, and advance...

Quantifying airway smooth muscle (ASM) in patients with asthma raises the possibility of improved and personalized disease management. Endobronchial polarization-sensitive optical coherence tomography (PS-OCT) is a promising quantitative imaging approach that is in the early stages of clinical translation. To date, only animal tissues have been use...

In clinical settings, precise biomechanical assessments of the cornea are crucial for early detection of keratoconus. Our study introduces the clinical application of a breakthrough multi-meridian technique that enables simultaneous 3-D deformation measurements, enhancing the diagnostic capabilities of standard air-puff swept-source OCT systems. By...

Background Breast density is a strong and potentially modifiable breast cancer risk factor. Almost everything we know about breast density has been derived from mammography, and therefore, very little is known about breast density in younger women aged <40. This study examines the acceptability and performance of two alternative breast density meas...

The ability to perform multi-meridian, simultaneous measurements of air-induced corneal deformation is expected to highly improve the accuracy of assessing corneal biomechanics. We propose a simplified method targeting 3-D deformation measurements that could be introduced to any swept-source OCT system. We utilize a spatial-depth-encoded multiplexi...

In the last decade, 3D printing systems have greatly evolved both in terms of processable materials and printing resolutions, becoming a top seed technology for many academic and industrial applications. Nevertheless, manufacturing polymeric materials characterized by a trabecular porosity and functionally graded architecture—where both the local p...

All-fiber-optic imaging microendoscopes are emerging as an important tool in bioimaging studies, but physical limitations constrain the achievable beam characteristics of designs using a single focusing element. These constraints are especially relevant for applications that require a long working distance, high resolution, and/or minimal probe dia...

Mammographic breast density is a strong breast cancer risk factor, and its routine clinical measurement could potentially be used to identify women at higher risk of breast cancer and/or monitor primary prevention strategies. Previous reports of optical breast spectroscopy (OBS), a novel approach to measuring breast density, demonstrated that it is...

Background: Noninvasive assessment of metabolic processes that sustain regeneration of human retinal visual pigments (visual cycle) is essential to improve ophthalmic diagnostics and to accelerate development of new treatments to counter retinal diseases. Fluorescent vitamin A derivatives, which are the chemical intermediates of these processes, a...

Many bioimaging studies, including those in engineered tissue constructs, intravital microscopy in animal models, and medical imaging in humans, require cellular-resolution imaging of structures deep within a sample. Yet, many of the current approaches are limited in terms of resolution, but also in invasiveness, repeatable imaging of the same loca...

OCT imaging of dynamic samples can give rise to significant misleading axial motion artifacts, depending on system specifications. Here, we investigate the axial shift phenomena in low-cost swept-source OCT dynamic measurements and simulations.

Corneal biomechanics play a fundamental role in the genesis and progression of corneal pathologies, such as keratoconus; in corneal remodeling after corneal surgery; and in affecting the measurement accuracy of glaucoma biomarkers, such as the intraocular pressure (IOP). Air-puff induced corneal deformation imaging reveals information highlighting...

Corneal biomechanics plays a fundamental role in the genesis and progression of corneal pathologies, such as keratoconus. It also contributes to corneal remodelling after corneal surgery, and it affects the measurement accuracy of glaucoma biomarkers, such as the intraocular pressure (IOP). Air-puff induced corneal deformation imaging reveals infor...

Significance: To advance our understanding of the contrast observed when imaging with polarization-sensitive optical coherence tomography (PS-OCT) and its correlation with oral cancerous pathologies, a detailed comparison with histology provided via ex vivo fixed tissue is required. The effects of tissue fixation, however, on such polarization-bas...

We present in-vivo imaging of the mouse brain using custom made Gaussian beam optical coherence microscopy (OCM) with 800nm wavelength. We applied new instrumentation to longitudinal imaging of the glioblastoma (GBM) tumor microvasculature in the mouse brain. We have introduced new morphometric biomarkers that enable quantitative analysis of the de...

Purpose: To introduce a new approach for keratoconus detection based on corneal microstructure observed in vivo derived from a single Scheimpflug image. Methods: Scheimpflug single-image snapshots from 25 control subjects and 25 keratoconus eyes were analyzed; from each group, five subjects were randomly selected to provide out-of-sample data. E...

Purpose : Ocular biomechanical simulations show that air-puff induced corneal deformation imaging (APCDI) can reveal pathological asymmetric responses, as in eccentric keratoconus. Such asymmetries often go undetected when monitoring deformation on only one meridian (Birkenfeld et al., IOVS, 2019), as is the case with commercial instruments. We pre...

We show that polarization‐sensitive optical coherence tomography angiography (PS‐OCTA) based on full Jones matrix assessment of speckle decorrelation offers improved contrast and depth of vessel imaging over conventional OCTA. We determine how best to combine the individual Jones matrix elements and compare the resulting image quality to that of a...

The organization of fibrillar tissue on the micrometer scale carries direct implications for health and disease but remains difficult to assess in vivo. Polarization-sensitive optical coherence tomography measures birefringence, which relates to the microscopic arrangement of fibrillar tissue components. Here, we demonstrate a critical improvement...

Purpose: We introduce a new approach to assess the properties of corneal microstructure in vivo of healthy control and keratoconus eyes, based on statistical modeling of light intensity distribution from Scheimpflug images. Methods: Twenty participants (10 mild keratoconus and 10 control eyes) were included in this study. Corneal biomechanics wa...

It is challenging to recover local optic axis orientation from samples probed with fiber-based polarization-sensitive optical coherence tomography (PS-OCT). In addition to the effect of preceding tissue layers, the transmission through fiber and system elements, and imperfect system alignment, need to be compensated. Here, we present a method to re...

Application of the air‐puff swept source OCT (SS‐OCT) instrument to determine the influence of viscoelasticity on the relation between overall the air‐puff force and corneal apex displacement of porcine corneas ex vivo is demonstrated. Simultaneous recording of time‐evolution of the tissue displacement and air pulse stimulus allows obtaining valuab...

We employ optical coherence tomography (OCT) and optical coherence microscopy (OCM) to study conjunctival lymphatics in porcine eyes ex vivo. This study is a precursor to the development of in vivo imaging of the collecting lymphatics for potentially guiding and monitoring glaucoma filtration surgery. OCT scans at 1300 nm and higher‐resolution OCM...

Standard optical systems in ophthalmology are strictly dedicated either to retinal or to anterior segment imaging due to the refractive properties of the eye. We demonstrate a swept source optical coherence tomography platform with an electrically tunable lens (ETL) for versatile 3D in vivo imaging of both the eye’s anterior segment and the retina....

In this paper, we describe a technique capable of visualizing mechanical properties at the cellular scale deep in living tissue, by incorporating a gradient-index (GRIN)-lens micro-endoscope into an ultrahigh-resolution optical coherence elastography system. The optical system, after the endoscope, has a lateral resolution of 1.6 µm and an axial re...

Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers’ ability to visualize the cellular a...

Polarisation sensitive optical coherence tomography (PS-OCT) offers additional intrinsic contrast to probe differences between healthy tissue and cancer that are often barely visible due to limited scattering contrast in an OCT image. PS-OCT reconstructs tissue birefringence from phase-sensitive measurements of orthogonal polarisation components of...

Optical coherence tomography (OCT) has been the most revolutionary diagnostic tool in eye care over the past 20 years. This paper reviews the current status and future directions of OCT in ophthalmic application.

In this paper, we use swept source optical coherence tomography combined with air-puff module (air-puff SS-OCT) to investigate the properties of the cornea. During OCT measurement the cornea was stimulated by short, air pulse, and corneal response was recorded. In this preliminary study, the air-puff SS-OCT instrument was applied to measure behavio...

Optical coherence elastography (OCE) is emerging as a potentially useful tool in the identification of a number of diseases. In our group, we are developing OCE techniques based on compressive loading. Typically, these techniques employ a quasi-static mechanical load introduced by uniaxially compressing a sample with a rigid plate. The resulting de...

Availability of the long-depth-range OCT systems enables comprehensive structural imaging of the eye and extraction of biometric parameters characterizing the entire eye. Several approaches have been developed to perform OCT imaging with extended depth ranges. In particular, current SS-OCT technology seems to be suited to visualize both anterior an...

We present a comprehensive imaging methodology for 3D structural and functional measurements of fertilized mouse oocytes. In contrary to methods used for mouse zygote imaging so far OCT provides 3D data without z axis movement of sample or objective lens. Furthermore, complex scanning protocols used in this study give access to different scales of...

A novel, time-resolved interferometric technique is presented allowing the reconstruction of the complex electric field output of a fast frequency swept laser in a single-shot measurement. The power of the technique is demonstrated by examining a short cavity swept source designed for optical coherence tomography applications, with a spectral bandw...

The labial minor salivary glands (LSGs) play a role in medical research and practice due to their superficial location and involvement in both systemic and localized diseases. Swept-source optical coherence tomography (OCT) is a noninvasive modality that enables in vivo, micrometer resolution, wide-field three-dimensional imaging in seconds. A purp...

A novel, time-resolved interferometric technique is presented that allows the reconstruction of the complex electric field output of a swept source laser in a single-shot measurement. The power of the technique is demonstrated by examining a short cavity swept source designed for optical coherence tomography (OCT) applications with a spectral width...