Evaluation of the biocompatibility of regenerated cellulose hydrogels with high strength and transparency for ocular applications.

Prompt emergency treatment for ocular injury, particularly in a battlefield setting, is essential to preserve vision, reduce pain, and prevent secondary infection. A bandage contact lens that could be applied in the field, at the time of injury, would protect the injured ocular surface until hospital treatment is available. Cellulose, a natural polymer, is widely used in biomedical applications including bandage materials.

Banded structures in collagen vitrigels for corneal injury repair.

There is a growing interest in using collagen vitrigels for corneal injury repair. We recently reported the synthesis and thermal denaturation behavior of these gels. In this paper, the banded structure in these vitrified gels is studied by small-angle X-ray scattering (SAXS) one-dimensional (1-D) correlation function analysis and transmission electron microscopy (TEM).

Structure and properties of collagen vitrigel membranes for ocular repair and regeneration applications.

The frequency of ocular injuries on the battlefield has been steadily increasing during recent conflicts. Combat-related eye injuries are difficult to treat and solutions requiring donor tissue are not ideal and are often not readily available. Collagen vitrigels have previously been developed for corneal reconstruction, but increased transparency and mechanical strength are desired for improved vision and ease of handling.

Evaluation of the effects of circular Descemet's membrane incision on the biomechanical, topographic and optical properties of rabbit corneas.

Background:   Prospective interventional animal case series to investigate quantitatively changes in corneal light-scattering, corneal hysteresis, keratometry and pachymetry induced by circular Descemet's membrane incision.

Methods:   Thirty mature New Zealand White rabbits were divided into three study groups: (i) surgical intervention with circular Descemet's incision; (ii) surgical control; and (iii) medical control. Group 1 eyes had two paracenteses placed 120 degrees apart and an 8.

Evaluation of Irradiated Corneas Using Scatterometry and Light and Electron Microscopy.

Objective: To determine if sterilization of donor corneas by irradiation alters optical, histologic, or ultrastructural tissue characteristics.

Methods: Blinded assessment of 10 irradiated and 10 nonirradiated donor corneas by a scatterometer used to objectively measure backscattered corneal light. Light and electron microscopy were performed on samples from both groups.

Evaluation of deep lamellar endothelial keratoplasty surgery using scatterometry and wavefront analyses.

Objective: To determine if postsurgical corneal interface abnormalities after deep lamellar endothelial keratoplasty (DLEK) cause increased light scattering or wavefront aberrations that may help to explain decreased best-corrected visual acuity in DLEK patients compared with penetrating keratoplasty (PK) patients.

Design: Prospective comparative case series.

Participants: Clinically clear corneas of 4 eyes that had undergone DLEK surgery and 4 eyes that had PK were studied.

Corneal endothelial injury thresholds for exposures to 1.54 micro m radiation.

The endothelial injury threshold was determined in rabbit for an 11-s exposure to 1.54 micro m radiation from an Erbium fiber laser. The beam was Gaussian with a 1/e diameter of 7 mm.

Light-scattering and ultrastructure of healed penetrating corneal wounds.

Purpose: To investigate quantitatively for the first time the relationship between light-scattering and ultrastructure of semitransparent scars resulting from penetrating wounds in rabbit cornea.

Methods: Penetrating wounds, 2 mm in diameter, were made in the central cornea and allowed to heal for 3.6 to 4.

Identical excimer laser PTK treatments in rabbits result in two distinct haze responses.

Purpose: To obtain objective light-scattering measurements to test a hypothesis that identical PTK treatments cause distinct low- and high-level light-scattering responses in rabbit corneas.

Methods: An excimer laser was used to produce identical 6-mm diameter phototherapeutic keratectomy treatments (PTK) in 32 pigmented rabbits. Eyes were treated by performing a 40-microm epithelial ablation, followed by a 100-mum stromal PTK.

Propagation of polarized light through two- and three-layer anisotropic stacks.

The extended Jones formulation is used to investigate propagation at nonnormal incidence through two- and three-layer systems of birefringent material in which the optic axes of the individual layers are in the plane of the layers. Such systems are equivalent to two optical elements in series-an equivalent retardation plate and a polarization rotator. Analytical solutions are obtained for the equivalent retardation and rotation.

corneal epithelial injury thresholds for exposures to 1.54 microm radiation-dependence on beam diameter.

Corneal epithelial injury thresholds have been determined for exposures to 1.54 mum infrared radiation from an Erbium fiber laser. Thresholds were determined for beam diameters from 0.

Corneal epithelial injury thresholds for multiple-pulse exposures to Tm:YAG laser radiation at 2.02 microm.

Corneal epithelial damage thresholds for exposures to sequences of pulses of 2.02 microm infrared radiation produced by a Tm:YAG laser were investigated. Thresholds were determined for sequences of pulses at frequencies of 1, 10, 20, and 100 Hz.