Light-Related Cutaneous Symptoms of Erythropoietic Protoporphyria and Associations With Light Sensitivity Measurements.

Importance: Erythropoietic protoporphyria (EPP) is a rare and underdiagnosed genetic disease characterized by painful sensitivity to light. A better understanding and characterization of its light-induced cutaneous symptoms may aid in the identification of EPP in patients.

Objectives: To describe the cutaneous symptoms of erythropoietic protoporphyria (EPP) and to determine if these symptoms are associated with the degree of light sensitivity.

Nanocaging Rose Bengal to Inhibit Aggregation and Enhance Photo-induced Oxygen Consumption.

Photosensitized crosslinking of proteins in tissues has many medical applications including sealing wounds, strengthening tissues, and beneficially altering tissue properties. Rose Bengal (RB) is used most frequently as the photosensitizer but is not as efficient as would be desired for broad utilization in medicine. Aggregation of RB, at the high concentrations used for medical treatments, decreases the yield of singlet oxygen, which mediates protein crosslinking.

Detection of singlet oxygen luminescence for experimental corneal rose bengal photodynamic antimicrobial therapy.

Rose bengal photodynamic antimicrobial therapy (RB-PDAT) treats corneal infection by activating rose bengal (RB) with green light to produce singlet oxygen (O). Singlet oxygen dosimetry can help optimize treatment parameters. We present a O dosimeter for detection of O generated during experimental RB-PDAT.

Influence of Rose Bengal Dimerization on Photosensitization.

Protein crosslinking photosensitized by rose Bengal (RB ) has multiple medical applications and understanding the photosensitization mechanism can improve treatment effectiveness. To this end, we investigated the photochemical efficiencies of monomeric RB (RB ) and dimeric RB (RB ) and the optimal pH for anaerobic RB photosensitization in cornea. Absorption spectra and dynamic light scattering (DLS) measurements were used to estimate the fractions of RB and RB .

Arginine as an Enhancer in Rose Bengal Photosensitized Corneal Crosslinking.

Purpose: Oxygen-independent cornea crosslinking (CXL) using rose bengal (RB) and green light may have unique clinical applications. These studies were designed to gain insight into the arginine (arg)-enhanced anaerobic crosslinking process, to maximize crosslinking efficiency, and to test a clinically feasible method for oxygen-free CXL.

Methods: Rabbit corneas were treated ex vivo using 1 mM RB and 532 nm light.

Corneal Collagen Ordering After In Vivo Rose Bengal and Riboflavin Cross-Linking.

Purpose: Photoactivated cornea collagen cross-linking (CXL) increases corneal stiffness by initiating formation of covalent bonds between stromal proteins. Because CXL depends on diffusion to distribute the photoinitiator, a gradient of CXL efficiency with depth is expected that may affect the degree of stromal collagen organization. We used second harmonic generation (SHG) microscopy to investigate the differences in stromal collagen organization in rabbit eyes after corneal CXL in vivo as a function of depth and time after surgery.

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.

Medical Applications of Rose Bengal- and Riboflavin-Photosensitized Protein Crosslinking.

This review summarizes research on many of the potential applications of photosensitized crosslinking of tissue proteins in surgery and current knowledge of the photochemical mechanisms underlying formation of the covalent protein-protein crosslinks involved. Initially developed to close wounds or reattach tissues, protein photocrosslinking has also been demonstrated to stiffen and strengthen tissues, decrease inflammatory responses and facilitate tissue bioengineering. These treatments appear to result largely from crosslinks within and between collagen molecules in tissue that typically form by an oxygen-dependent mechanism.

Enhancing Rose Bengal-Photosensitized Protein Crosslinking in the Cornea.

Purpose: Rose bengal (RB)-photosensitized protein crosslinking has been proposed for several applications in the eye. This study identifies oxygen-dependent and oxygen-independent mechanistic pathways in cornea for RB-photosensitized crosslinking to enhance its efficiency for ocular treatments.

Methods: Rabbit corneas ex vivo were stained with 1 mM RB and irradiated at 532 nm.

Rose Bengal and Green Light Versus Riboflavin-UVA Cross-Linking: Corneal Wound Repair Response.

Purpose: To study corneal wound healing after two cross-linking techniques using either rose bengal and green light (RGX) or the conventional treatment using riboflavin and UVA radiation (UVX).

Methods: Corneas of New Zealand rabbits were monolaterally treated with UVX (21 eyes) or RGX (25 eyes). Treatments involved corneal de-epithelialization (8-mm diameter), soaking with photosensitizer (0.

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.

Sealing of Corneal Lacerations Using Photoactivated Rose Bengal Dye and Amniotic Membrane.

Purpose: Watertight closure of perforating corneoscleral lacerations is necessary to prevent epithelial ingrowth, infection, and potential loss of the eye. Complex lacerations can be difficult to treat, and repair with sutures alone is often inadequate. In this study, we evaluated a potentially sutureless technology for sealing complex corneal and scleral lacerations that bonds the amniotic membrane (AM) to the wound using only green light and rose bengal dye.

Rose Bengal Binding to Collagen and Tissue Photobonding.

We investigated two critical aspects of rose Bengal (RB) photosensitized protein cross-linking that may underlie recently developed medical applications. Our studies focused on the binding of RB to collagen by physical interaction and the effect of this binding and certain amino acids on RB photochemistry. Molecular dynamics simulations and free-energy calculation techniques, complemented with isothermal titration calorimetry, provided insight into the binding between RB and a collagen-like peptide (CLP) at the atomic level.

Variations in the endogenous fluorescence of rabbit corneas after mechanical property alterations.

Keratoconus is an eye disease in which the cornea progressively deforms due to loss of cornea mechanical rigidity, and thus causes deterioration of visual acuity. Techniques to characterize the mechanical characteristics of the cornea are important to better monitor changes and response to treatments. To investigate the feasibility of using the endogenous fluorescence of cornea for monitoring alterations of its mechanical rigidity, linear tensiometry was used to quantitate stiffness and Young's modulus (YM) after treatments that increase cornea stiffness (collagen photocross-linking) or decrease stiffness (enzymatic digestion).

Corneal Wound Repair After Rose Bengal and Green Light Crosslinking: Clinical and Histologic Study.

Purpose: To evaluate corneal wound healing after treatment with a new collagen crosslinking protocol using rose bengal dye and green light (RGX).

Methods: One cornea of 20 New Zealand rabbits was de-epithelialized (DE) in an 8-mm diameter circle and, in another group (n = 25), the DE corneas were then stained with 0.1% rose bengal for 2 minutes and exposed to green light (532 nm) for 7 minutes (RGX).

Flexible Optical Waveguides for Uniform Periscleral Cross-Linking.

Purpose: Scleral cross-linking (SXL) with a photosensitizer and light is a potential strategy to mechanically reinforce the sclera and prevent progressive axial elongation responsible for severe myopia. Current approaches for light delivery to the sclera are cumbersome, do not provide uniform illumination, and only treat a limited area of sclera. To overcome these challenges, we developed flexible optical waveguides optimized for efficient, homogeneous light delivery.

An intraluminal stent facilitates light-activated vascular anastomosis.

Background: Photochemical tissue bonding (PTB) is a sutureless, light-activated technique that produces a watertight, microvascular repair with minimal inflammation compared to standard microsurgery. However, it is practically limited by the need for a clinically viable luminal support system. The aim of this study was to evaluate a hollow biocompatible stent to provide adequate luminal support to facilitate vascular anastomosis using the PTB technique.

Biomechanical Changes After In Vivo Collagen Cross-Linking With Rose Bengal-Green Light and Riboflavin-UVA.

Purpose: To compare corneal biomechanical properties after in vivo and ex vivo cross-linking (CXL) using rose bengal-green light (RGX) or riboflavin-UVA (UVX).

Methods: Corneas of 30 rabbits were treated in vivo by the two CXL modalities monolaterally (Group 1) or bilaterally (Group 2). Rabbits in Group 1 were euthanized 1 month after treatments and in Group 2 two months after treatment.

Collagen-Based Photoactive Agent for Tissue Bonding.

Using a combination of methacrylated collagen and the photosensitizer rose Bengal, a new light-activated biomimetic material for tissue sutureless bonding was developed. This formulation was cross-linked using green light. In vivo tests in mice demonstrate the suitability of the material for sutureless wound closure.

Antimicrobial Blue Light Therapy for Infectious Keratitis: Ex Vivo and In Vivo Studies.

Purpose: To investigate the effectiveness of antimicrobial blue light (aBL) as an alternative or adjunctive therapeutic for infectious keratitis.

Methods: We developed an ex vivo rabbit model and an in vivo mouse model of infectious keratitis. A bioluminescent strain of Pseudomonas aeruginosa was used as the causative pathogen, allowing noninvasive monitoring of the extent of infection in real time via bioluminescence imaging.

Corneal Resistance to Keratolysis After Collagen Crosslinking With Rose Bengal and Green Light.

Purpose: The purpose of this study was to evaluate the resistance to degradation by collagenase A of corneas that have been crosslinked with Rose Bengal and green light (RGX).

Methods: The ex vivo crosslinking procedure was performed on enucleated rabbit corneas. Corneas were deepithelialized after applying 30% alcohol.

Corneal Crosslinking With Rose Bengal and Green Light: Efficacy and Safety Evaluation.

Purpose: To evaluate crosslinking of cornea in vivo using green light activation of Rose Bengal (RGX) and assess potential damaging effects of the green light on retina and iris.

Methods: Corneas of Dutch belted rabbits were de-epithelialized, then stained with Rose Bengal and exposed to green light, or not further treated. Corneal stiffness was measured by uniaxial tensiometry.