Algorithm and software for field distortion correction in a commercial SD-OCT for corneal curvature assessment.

Accurate assessment of corneal curvatures using frequency domain optical coherence tomography (OCT) with galvanometer scanners remains challenging due to the well-known scan field distortion. This paper presents an algorithm and software for correcting the distortion using only two simple measurements in which a readily available standard sphere is positioned in different depths in front of the OCT scanner. This offers a highly accessible and easily reproducible method for the field distortion correction (FDC).

Algorithms for optoacoustically controlled selective retina therapy (SRT).

Objectives: Selective Retina Therapy (SRT) uses microbubble formation (MBF) to target retinal pigment epithelium (RPE) cells selectively while sparing the neural retina and the choroid. Intra- and inter-individual variations of RPE pigmentation makes frequent radiant exposure adaption necessary. Since selective RPE cell disintegration is ophthalmoscopically non-visible, MBF detection techniques are useful to control adequate radiant exposures.

Advances in Imaging of Subbasal Corneal Nerves With Micro-Optical Coherence Tomography.

Purpose: To investigate the most peripheral corneal nerve plexus using high-resolution micro-optical coherence tomography (µOCT) imaging and to assess µOCT's clinical potential as a screening tool for corneal and systemic diseases.

Methods: An experimental high-resolution (1.5 × 1.

Investigations on Retinal Pigment Epithelial Damage at Laser Irradiation in the Lower Microsecond Time Regime.

Purpose: New lasers with a continuous wave power exceeding 15 W are currently investigated for retinal therapies, promising highly localized effects at and close to the Retinal Pigment Epithelium (RPE). The goal of this work is to evaluate mechanisms and thresholds for RPE cell damage by means of pulse durations up to 50 µs.

Methods: A diode laser with a wavelength of 514 nm, a power of 15 W, and adjustable pulse durations between 2 µs and 50 µs was used.

Micro-optical coherence tomography for high-resolution morphologic imaging of cellular and nerval corneal micro-structures.

We demonstrate the highest resolution (1.5×1.5×1 µm) micrometer optical coherence tomography (µOCT) imaging of the morphologic micro-structure of excised swine and non-human primate corneas.

Corneal Stromal Filler Injection as a Novel Approach to Correct Presbyopia-An Pilot Study.

Purpose: To evaluate the feasibility of corneal stromal filler injection to create bifocality to correct presbyopia by flattening the central posterior corneal surface and thus increase refractive power.

Methods: Femtosecond laser-assisted corneal stromal pockets of varying diameters close to the posterior corneal curvature were cut into rabbit eyes . Subsequently, hyaluronic acid was injected to flatten the central posterior curvature.

Stromal Nerve Imaging and Tracking Using Micro-Optical Coherence Tomography.

Purpose: To image, track and map the nerve fiber distribution in excised rabbit corneas over the entire stromal thickness using micro-optical coherence tomography (µOCT) to develop a screening tool for early peripheral neuropathy.

Methods: Excised rabbit corneas were consecutively imaged by a custom-designed µOCT prototype and a commercial laser scanning fluorescence confocal microscope. The µOCT images with a field of view of approximately 1 × 1 mm were recorded with axial and transverse resolutions of approximately 1 µm and approximately 4 µm, respectively.

Refractive Changes After Corneal Stromal Filler Injection for the Correction of Hyperopia.

Purpose: To evaluate a new non-ablative and adjustable procedure for laser ablative refractive corneal surgery in hyperopia using the injection of a biocompatible liquid filler material into a stromal pocket.

Methods: A total of 120 stromal pockets were created using a clinical femtosecond laser system in 96 rabbit corneoscleral discs and 24 whole globes. Pockets were cut at a depth of 120 or 250 µm below the epithelial surface.

Capillary Refill-The Key to Assessing Dermal Capillary Capacity and Pathology in Optical Coherence Tomography Angiography.

Background/objectives: Standard optical coherence tomography angiography (OCTA) has been limited to imaging blood vessels actively undergoing perfusion, providing a temporary picture of surface microvasculature. Capillary perfusion in the skin is dynamic and changes in response to the surrounding tissue's respiratory, nutritional, and thermoregulatory needs. Hence, OCTA often represents a given perfusion state without depicting the actual extent of the vascular network.

Selective Equatorial Sclera Crosslinking in the Orbit Using a Metal-Coated Polymer Waveguide.

Purpose: Photochemical crosslinking of the sclera is an emerging technique that may prevent excessive eye elongation in pathologic myopia by stiffening the scleral tissue. To overcome the challenge of uniform light delivery in an anatomically restricted space, we previously introduced the use of flexible polymer waveguides. We presently demonstrate advanced waveguides that are optimized to deliver light selectively to equatorial sclera in the intact orbit.

Correction of hyperopia by intrastromal cutting and liquid filler injection.

Correction of hyperopia requires an increase of the refractive power by steepening of the corneal surface. Present refractive surgical techniques based on corneal ablation (LASIK) or intrastromal lenticule extraction (SMILE) are problematic due to epithelial regrowth. Recently, it was shown that correction of low hyperopia can be achieved by implanting intracorneal inlays or allogeneic lenticules.

Optimization-based vessel segmentation pipeline for robust quantification of capillary networks in skin with optical coherence tomography angiography.

Optical coherence tomography angiography (OCTA) provides in-vivo images of microvascular perfusion in high resolution. For its application to basic and clinical research, an automatic and robust quantification of the capillary architecture is mandatory. Only this makes it possible to reliably analyze large amounts of image data, to establish biomarkers, and to monitor disease developments.

Selective retina therapy: toward an optically controlled automatic dosing.

Selective retina therapy (SRT) targets the retinal pigment epithelium (RPE) with pulsed laser irradiation by inducing microbubble formation (MBF) at the intracellular melanin granula, which leads to selective cell disruption. The following wound healing process rejuvenates the chorio-retinal junction. Pulse energy thresholds for selective RPE effects vary intra- and interindividually.

Simple approach for aberration-corrected OCT imaging of the human retina.

Aberration-corrected imaging of human photoreceptor cells, whether hardware or software based, presently requires a complex and expensive setup. Here we use a simple and inexpensive off-axis full-field time-domain optical coherence tomography (OCT) approach to acquire volumetric data of an in vivo human retina. Full volumetric data are recorded in 1.

Enhanced quantification of metabolic activity for individual adipocytes by label-free FLIM.

Fluorescence lifetime imaging microscopy (FLIM) of intrinsic fluorophores such as nicotinamide adenine dinucleotide (NADH) allows for label-free quantification of metabolic activity of individual cells over time and in response to various stimuli, which is not feasible using traditional methods due to their destructive nature and lack of spatial information. This study uses FLIM to measure pharmacologically induced metabolic changes that occur during the browning of white fat. Adipocyte browning increases energy expenditure, making it a desirable prospect for treating obesity and related disorders.

Assessment of skin lesions produced by focused, tunable, mid-infrared chalcogenide laser radiation.

Background: Traditionally, fractional laser treatments are performed with focused laser sources operating at a fixed wavelength. Using a tunable laser in the mid-infrared wavelength range, wavelength-dependent absorption properties on the ablation process and thermal damage formation were assessed with the goal to obtain customizable tissue ablations to provide guidance in finding optimized laser exposure parameters for clinical applications.

Methods: Laser tissue experiments were carried out on full thickness ex vivo human abdominal skin using a mid-infrared tunable chromium-doped zinc selenide/sulfide chalcogenide laser.

Interface Bonding With Corneal Crosslinking (CXL) After LASIK Ex Vivo.

Purpose: Interface bonding with corneal crosslinking (CXL) after LASIK using two different photosensitizers was studied ex vivo.

Methods: A LASIK flap was created in enucleated rabbit eyes using a femtosecond laser. After the dissection, CXL was performed to seal the interface.

Power-controlled temperature guided retinal laser therapy.

Laser photocoagulation has been a treatment method for retinal diseases for decades. Recently, studies have demonstrated therapeutic benefits for subvisible effects. A treatment mode based on an automatic feedback algorithm to reliably generate subvisible and visible irradiations within a constant irradiation time is introduced.

Biomedical optics centers: forty years of multidisciplinary clinical translation for improving human health.

Despite widespread government and public interest, there are significant barriers to translating basic science discoveries into clinical practice. Biophotonics and biomedical optics technologies can be used to overcome many of these hurdles, due, in part, to offering new portable, bedside, and accessible devices. The current JBO special issue highlights promising activities and examples of translational biophotonics from leading laboratories around the world.

In-vivo retinal imaging with off-axis full-field time-domain optical coherence tomography.

With a simple setup, mainly composed of a low coherence light source and a camera, full-field optical coherence tomography (FF-OCT) allows volumetric tissue imaging. However, fringe washout constrains its use in retinal imaging. Here, we present a novel motion-insensitive approach to FF-OCT, which introduces path-length differences between the reference and the sample light in neighboring pixels using an off-axis reference beam.

Lesion strength control by automatic temperature guided retinal photocoagulation.

Laser photocoagulation is an established treatment for a variety of retinal diseases. However, when using the same irradiation parameter, the size and strength of the lesions are unpredictable due to unknown inter- and intraindividual optical properties of the fundus layers. The aim of this work is to investigate a feedback system to generate desired lesions of preselectable strengths by automatically controlling the irradiation time.

Polyacrylamide gel substrates that simulate the mechanical stiffness of normal and malignant neuronal tissues increase protoporphyin IX synthesis in glioma cells.

Protoporphyrin IX (PPIX) produced following the administration of exogenous 5d-aminolevulinic acid is clinically approved for photodynamic therapy and fluorescence-guided resection in various jurisdictions around the world. For both applications, quantification of PPIX forms the basis for accurate therapeutic dose calculation and identification of malignant tissues for resection. While it is well established that the PPIX synthesis and accumulation rates are subject to the cell’s biochemical microenvironment, the effect of the physical microenvironment, such as matrix stiffness, has received little attention to date.

Light-Controlled Delivery of Monoclonal Antibodies for Targeted Photoinactivation of Ki-67.

The selective inhibition of intracellular and nuclear molecules such as Ki-67 holds great promise for the treatment of cancer and other diseases. However, the choice of the target protein and the intracellular delivery of the functional agent remain crucial challenges. Main hurdles are (a) an effective delivery into cells, (b) endosomal escape of the delivered agents, and (c) an effective, externally triggered destruction of cells.

Non-invasive transdermal two-dimensional mapping of cutaneous oxygenation with a rapid-drying liquid bandage.

Oxygen plays an important role in wound healing, as it is essential to biological functions such as cell proliferation, immune responses and collagen synthesis. Poor oxygenation is directly associated with the development of chronic ischemic wounds, which affect more than 6 million people each year in the United States alone at an estimated cost of $25 billion. Knowledge of oxygenation status is also important in the management of burns and skin grafts, as well as in a wide range of skin conditions.