Maciej Wojtkowski

Maciej Wojtkowski
Institute of Physical Chemistry | ICF · International Center for Translational Eye Research

Doctor of Philosophy

About

332
Publications
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11,505
Citations

Publications

Publications (332)
Conference Paper
Purpose : The perceived brightness of different visible light sources can be compared with photometric units based on the standardized luminosity curves (300-780nm range). As reported previously (PNAS 111(50), pp. E5445-E5454 (2014)), near-infrared (NIR) radiation can cause isomerization of visual pigments by one- or two-photon absorption. The perc...
Article
We demonstrate in vivo imaging of the ischemic area in the mouse brain after photostroke using a custom prototype Gaussian‑beam optical coherence tomography (OCT) setup in which the near infrared imaging beam and the green photoinducing light pass through the same objective lens. The goal of our research was analysis of vascularity of the ischemic...
Article
Full-text available
We report the development of a widely-tunable femtosecond fiber laser system and its application for two-photon vision studies. The source is based on an Er-doped fiber laser with spectral shift up to 2150 nm, followed by a second harmonic generation module to generate a frequency-doubled beam tunable from 872 to 1075 nm. The source delivers sub-23...
Article
For many years electroretinography (ERG) has been used for obtaining information about the retinal physiological function. More recently, a new technique called optoretinography (ORG) has been developed. In one form of this technique, the physiological response of retinal photoreceptors to visible light, resulting in a nanometric photoreceptor opti...
Article
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) is an emerging tool for high-speed eye imaging. However, cross-talk formation in images limits the imaging depth. To this end, we have recently shown that reducing spatial coherence with a fast deformable membrane can suppress the noise but over a limited axial range and with substa...
Article
Full-text available
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...
Preprint
One of the greatest needs in modern ophthalmology is access to the eye choroid in vivo. Without it, it is difficult to introduce new therapies and to understand most of the pathological changes in the eye, because of the total blood flow in the eye is caused by the choroidal circulation. It is entirely responsible for the metabolism of photorecepto...
Conference Paper
Purpose : Two-photon vision is associated with the perception of short pulses of near-infrared (NIR) laser radiation as a visible (VIS) light. It is caused by the nonlinear process of two-photon absorption by visual pigments. The longer wavelength of the stimulating radiation suggests that this phenomenon may be beneficial for functional visual exa...
Conference Paper
Pulsed near-infrared (NIR) light sources can be successfully applied for both imaging and functional testing of the human eye, as published recently. These two groups of applications have different requirements. For imaging applications, the most preferable is invisible scanning beam while efficiently visible stimulating beam is preferable for func...
Article
Full-text available
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) has recently emerged as a fast alternative to point-scanning confocal OCT in eye imaging. However, when imaging the cornea with FD-FF-OCT, a spatially coherent laser can focus down on the retina to a spot that exceeds the maximum permissible exposure level. Here we demonstrate that...
Conference Paper
Spatiotemporal optical coherence (STOC) manipulation is a new method for crosstalk-free, aberration-free, high-speed, high-resolution imaging of the human eye in vivo . Here, we apply STOC for deep blood flow imaging of the human retina in vivo .
Conference Paper
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.
Conference Paper
The two- and one-photon visual sensitivities (2phS and 1phS) of cataract patients were tested before and after IOL surgery. Mean change in 2phS was twice smaller than 1phS indicating that 2phS is less affected by cataract.
Conference Paper
We developed and applied spectral laser doppler holography (SLDH) to Fourier-Domain Full-Field Optical Coherence Tomography (FD-FF-OCT) enabling visualization and quantification of the human retinal blood flow at high speeds and high transverse resolution in vivo .
Conference Paper
We present an optimized Fourier-domain full-field optical coherence tomography system for corneal in vivo imaging that uses a line camera for real-time cross-sectional preview and a multimode fiber for preventing retinal damage.
Article
Full-text available
Droplet microfluidics disrupted analytical biology with the introduction of digital polymerase chain reaction and single-cell sequencing. The same technology may also bring important innovation in the analysis of bacteria, including antibiotic susceptibility testing at the single-cell level. Still, despite promising demonstrations, the lack of a hi...
Article
Full-text available
Two-photon vision is a phenomenon associated with the perception of short pulses of near-infrared radiation (900-1200 nm) as a visible light. It is caused by the nonlinear process of two-photon absorption by visual pigments. Here we present results showing the influence of pulse duration and repetition rate of short pulsed lasers on the visual thre...
Conference Paper
Full-text available
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...
Article
Full-text available
Corneal biomechanics plays 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...
Article
Significance Two-photon excitation (TPE) of retinal fluorophores with infrared light allows monitoring metabolic transformation of the retina. TPE imaging can provide information about biochemical events that precede structural damage to the retina and thereby accelerate the development of therapies against blinding diseases. While subcellular TPE...
Article
Full-text available
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...
Article
Full-text available
Purpose To investigate the effect of short‐term scleral lens wear on the corneal stroma at a macroscopic (thickness) and microscopic (within tissue) level, including regional variations. Methods Fourteen young, healthy participants wore a rotationally symmetric, 16.5 mm diameter, scleral lens for 8 h. Scheimpflug images were captured before, and i...
Article
A femtosecond frequency-doubled erbium-doped fiber laser with an adjustable pulse repetition rate is developed and applied in two-photon excited fluorescence microscopy. The all-fiber laser system provides the fundamental pulse at 1560 nm wavelength with 22 fs duration for the second harmonic generation, resulting in 1.35 nJ, 60 fs pulses at 780 nm...
Article
Full-text available
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...
Conference Paper
Full-text available
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...
Preprint
A femtosecond frequency-doubled Erbium-doped fiber laser with adjustable pulse repetition rate is developed and applied in two-photon excited fluorescence microscopy. The all-fiber laser system provides the fundamental pulse at 1560 nm wavelength with 22 fs duration for the second harmonic generation, resulting in 1.35 nJ, 60 fs pulses at 780 nm. T...
Article
Full-text available
Corneal evaluation in ophthalmology necessitates cellular-resolution and fast imaging techniques that allow for accurate diagnoses. Currently, the fastest volumetric imaging technique is Fourier-domain full-field optical coherence tomography (FD-FF-OCT), which uses a fast camera and a rapidly tunable laser source. Here, we demonstrate high-resoluti...
Preprint
Full-text available
Corneal evaluation in ophthalmology necessitates cellular-resolution and fast imaging techniques allowing accurate diagnoses. Currently, the fastest volumetric imaging technique is Fourier-domain full-field optical coherence tomography (FD-FF-OCT) that uses a fast camera and a rapidly tunable laser source. Here, we demonstrate high-resolution, high...
Article
Full-text available
Spatiotemporal optical coherence (STOC) imaging is a new technique for suppressing coherent cross talk noise in Fourier-domain full-field optical coherence tomography (FD-FF-OCT). In STOC imaging, the time-varying inhomogeneous phase masks modulate the incident light to alter the interferometric signal. Resulting interference images are then proces...
Article
We used a new multimodal imaging system that combines optical coherence microscopy and brightfield microscopy. Using this in vivo brain monitoring approach and cranial window implantation, we three-dimensionally visualized the vascular network during thrombosis, with high temporal (18 s) and spatial (axial, 2.5 μ m ; lateral, 2.2 μ m ) reso...
Conference Paper
We apply coherent averaging and digital aberration correction to spatiotemporal optical coherence (STOC) imaging to achieve aberration-free, crosstalk-free volumetric imaging. We demonstrate results of ex vivo samples and human in vivo retinal and corneal imaging.
Preprint
Spatiotemporal optical coherence (STOC) imaging is a new technique for suppressing coherent crosstalk noise in Fourier-domain full-field optical coherence tomography (FD-FF-OCT). In STOC imaging, the timevarying inhomogeneous phase masks modulate the incident light to alter the interferometric signal. Resulting interference images are then processe...
Article
Full-text available
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) is currently the fastest volumetric imaging technique that is able to generate a single 3-D volume of retina in less than 9 ms, corresponding to a voxel rate of 7.8 GHz. FD-FF-OCT is based on a fast camera, a rapidly tunable laser source, and Fourier-domain signal detection. However...
Article
Full-text available
Microperimetry is a subjective ophthalmologic test used to assess retinal function at various specific and focal locations of the visual field. Historically, visible light has been described as ranging from 400 to 720 nm. However, we previously demonstrated that infra-red light can initiate visual transduction in rod photoreceptors by a mechanism o...
Conference Paper
The aim of this paper is to present a novel method, called Adaptive Edge Detection (AED), of extraction of precise pupil edge coordinates from eye image characterized by reflections of external illuminators and laser beams. The method is used for monitoring of pupil size and position during psychophysical tests of two-photon vision performed by ded...
Article
Full-text available
Two-photon vision arises from the perception of pulsed infrared (IR) laser light as color corresponding to approximately half of the laser wavelength. The physical process responsible for two-photon vision in rods has been delineated and verified experimentally only recently. Here, we sought to determine whether IR light can also be perceived by ma...
Article
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...
Article
Full-text available
We demonstrate a swept source OCT-based ocular biometer integrated with an air-puff stimulus to study the reaction of the eye to mechanical stimulation in vivo. The system enables simultaneous measurement of the stimulus strength and high-speed imaging of the eye dynamics along the visual axis. We characterize the stimulus and perform optimization...
Article
Optical Coherence Imaging (OCI) including Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) uses interferometric detection to generate high-resolution volumetric images of the sample at high speeds. Such capabilities are significant for in vivo imaging, including ophthalmology, brain, intravascular imaging, as well as endosc...
Conference Paper
Purpose : Near infrared (NIR) light can cause isomerization of visual pigments by one-photon absorption resulting in the perception of its color as red. Lately it was shown that for short-pulsed infrared lasers, two-photon absorption also causes isomerization of visual pigments - then perceived color corresponds to half of wavelength of the laser....