Optical Quality and Visual Performance With Different Toric Contact Lens Designs.

OBJECTIVES: To evaluate the optical quality of different toric contact lens (CL) designs and compare their on-eye visual correction performance. METHODS: Twenty soft CL wearers aged 20 to 39 years were enrolled. Two daily disposable silicone-hydrogel toric CLs were tested: the "Eyelid Stabilized Design" (ESD-CL) and prism-ballast design (PB-CL); a spherical daily disposable silicone hydrogel CL (spherical CL) was used as a control. On-eye performance was compared for corrected distance visual acuity (CDVA), astigmatism, and ocular higher-order aberrations (HOAs); astigmatism and ocular HOAs were measured with a wavefront sensor. The subjective quality of vision, rated for "blurred vision" and "double vision," lens rotation, and fitting were also compared. RESULTS: The ESD-CLs, PB-CL, and no-CL provided better CDVA than spherical CL ( P <0.05). Compared with spherical CL and no CL, PB-CL and ESD-CLs caused significantly lesser astigmatism ( P <0.05). Coma was significantly lesser with ESD-CLs than that with PB-CL ( P <0.05); total HOAs did not differ among the four conditions. The subjective ratings for blurred and double vision were significantly lower with ESD-CLs than those with spherical CL ( P <0.05). CONCLUSIONS: Toric CLs provide a better CDVA than spherical CLs. However, differences in coma and subjective symptoms may occur because of the design of toric CLs.

Localization and osteoblastic differentiation potential of neural crest-derived cells in oral tissues of adult mice.

In embryos, neural crest cells emerge from the dorsal region of the fusing neural tube and migrate throughout tissues to differentiate into various types of cells including osteoblasts. In adults, subsets of neural crest-derived cells (NCDCs) reside as stem cells and are considered to be useful cell sources for regenerative medicine strategies. Numerous studies have suggested that stem cells with a neural crest origin persist into adulthood, especially those within the mammalian craniofacial compartment. However, their distribution as well as capacity to differentiate into osteoblasts in adults is not fully understood. To analyze the precise distribution and characteristics of NCDCs in adult oral tissues, we utilized an established line of double transgenic (P0-Cre/CAG-CAT-EGFP) mice in which NCDCs express green fluorescent protein (GFP) throughout their life. GFP-positive cells were scattered like islands throughout tissues of the palate, gingiva, tongue, and buccal mucosa in adult mice, with those isolated from the latter shown to form spheres, typical cell clusters composed of stem cells, under low-adherent conditions. Furthermore, GFP-positive cells had markedly increased alkaline phosphatase (a marker enzyme of osteoblast differentiation) activity and mineralization as shown by alizarin red staining, in the presence of bone morphogenetic protein (BMP)-2. These results suggest that NCDCs reside in various adult oral tissues and possess potential to differentiate into osteoblastic cells. NCDCs in adults may be a useful cell source for bone regeneration strategies.

Biocompatibility and durability of Teflon-coated platinum-iridium wires implanted in the vitreous cavity.

Teflon-coated platinum-iridium wires are placed in the vitreous as electrodes in artificial vision systems. The purpose of this study was to determine whether these wires have toxicity in the vitreous cavity, and to examine the durability of their coating when grasped by forceps. Rabbits were implanted with platinum-iridium wires that were 50 µm in diameter and coated with Teflon to a total diameter of 68 or 100 µm. To examine the biocompatibility, electroretinograms (ERGs) and fluorescein angiography (FA) were performed before and 1 week, 1, 3, and 6 months after the implantation of the electrode. After 6 months, the eyes were histologically examined with light microscopy. To check the durability, the surface of a coated wire was examined with scanning electron microscopy after grasping with different types of forceps. At all times after the implantation the amplitudes and implicit times of the ERGs recorded were not significantly different from those recorded before the implantation (P > 0.05). FA showed no notable change during the follow-up periods. Histological studies showed that the retinas were intact after 6 months of implantation. There was no damage to the Teflon-coated wire after grasping the wire with forceps with silicon-coated tips, while surface damage of the Teflon that did not extend to the platinum-iridium wire was found when grasped by vitreoretinal forceps. We conclude that Teflon-coated platinum-iridium wire is highly biocompatible in the vitreous for at least 6 months. Wires should be handled with vitreoretinal forceps with silicone-coated tips in order to avoid causing damage during wire manipulation.

Reconstruction of functional tissues with cell sheet engineering.

The field of tissue engineering has yielded several successes in early clinical trials of regenerative medicine using living cells seeded into biodegradable scaffolds. In contrast to methods that combine biomaterials with living cells, we have developed an approach that uses culture surfaces grafted with the temperature-responsive polymer poly(N-isoproplyacrylamide) that allows for controlled attachment and detachment of living cells via simple temperature changes. Using cultured cell sheets harvested from temperature-responsive surfaces, we have established cell sheet engineering to create functional tissue sheets to treat a wide range of diseases from corneal dysfunction to esophageal cancer, tracheal resection, and cardiac failure. Additionally, by exploiting the unique ability of cell sheets to generate three-dimensional tissues composed of only cultured cells and their deposited extracellular matrix, we have also developed methods to create thick vascularized tissues as well as, organ-like systems for the heart and liver. Cell sheet engineering therefore provides a novel alternative for regenerative medicine approaches that require the re-creation of functional tissue structures.

Clinical Findings of Anterior Segment Spectral Domain Optical Coherence Tomography Images in Cytomegalovirus Corneal Endotheliitis.

PURPOSE: To evaluate the morphological characteristics of posterior corneal regions including keratic precipitates in eyes with cytomegalovirus (CMV) corneal endotheliitis using anterior segment spectral domain optical coherence tomography (SD-OCT). METHODS: Thirteen eyes of 13 patients with polymerase chain reaction-proven CMV corneal endotheliitis were included in this study. Slit-lamp images and anterior segment SD-OCT images of the posterior cornea were obtained to analyze the clinical characteristics of corneal structures and keratic precipitates. Morphological changes in the posterior cornea throughout the course of an antiviral treatment were also investigated. RESULTS: Anterior SD-OCT images showed protruding structures at the posterior cornea. These protruding structures exhibited dendritic, dome-shaped, quadrangular, or saw-tooth appearance, and reflectivity of these structures was high. Reflectivity of posterior corneal images including the endothelium and deep stromal corneal regions were also high (76.9%). Because corneal inflammation and corneal edema improved, the protruding structures and high-intensity regions of posterior corneal images were resolved after a course of antiviral treatment. CONCLUSIONS: The anterior segment SD-OCT examination represents a useful noninvasive alternative to diagnose and monitor CMV corneal endotheliitis.

A Self-Assembling Peptide Gel as a Vitreous Substitute: A Rabbit Study.

Purpose: To evaluate a self-assembling peptide gel as a potential vitreous substitute. Methods: PanaceaGel SPG-178, a self-assembling peptide gel, was diluted with distilled water and a balanced salt solution to achieve a final peptide concentration of 0.1%. The gel's refractive index, visible light transmission rate, and rheologic properties were investigated. The gel's biocompatibility was evaluated by examining the cellular viability (live and dead staining) and proliferation rate (alamarBlue assay). A 25-G pars plana vitrectomy was performed on the right eye of 21 New Zealand white rabbits. The gel was then injected into the vitreous cavity of 15 eyes. Six eyes were injected with a balanced salt solution (BSS) and served as controls. Toxicity was examined using electroretinography and histologic analysis after the injection of the gel. Results: The gel's physical properties closely resembled those of human vitreous. The gel showed no apparent toxicity. When the gel was injected into the vitreous cavity, fragmentation was not observed. Additionally, the gel remained transparent in the vitreous cavity and no complications were observed for 3 months after the injection. Electroretinography and histology confirmed the gel's biocompatibility. Conclusions: This diluted self-assembling peptide gel could be provide a promising vitreous substitute.

Cell delivery in regenerative medicine: the cell sheet engineering approach.

Recently, cell-based therapies have developed as a foundation for regenerative medicine. General approaches for cell delivery have thus far involved the use of direct injection of single cell suspensions into the target tissues. Additionally, tissue engineering with the general paradigm of seeding cells into biodegradable scaffolds has also evolved as a method for the reconstruction of various tissues and organs. With success in clinical trials, regenerative therapies using these approaches have therefore garnered significant interest and attention. As a novel alternative, we have developed cell sheet engineering using temperature-responsive culture dishes, which allows for the non-invasive harvest of cultured cells as intact sheets along with their deposited extracellular matrix. Using this approach, cell sheets can be directly transplanted to host tissues without the use of scaffolding or carrier materials, or used to create in vitro tissue constructs via the layering of individual cell sheets. In addition to simple transplantation, cell sheet engineered constructs have also been applied for alternative therapies such as endoscopic transplantation, combinatorial tissue reconstruction, and polysurgery to overcome limitations of regenerative therapies and cell delivery using conventional approaches.

Functional bioengineered corneal epithelial sheet grafts from corneal stem cells expanded ex vivo on a temperature-responsive cell culture surface.

BACKGROUND: Limbal stem-cell deficiency by ocular trauma or diseases causes corneal opacification and visual loss. Recent attempts have been made to fabricate corneal epithelial graft constructs, but the technology is still evolving. We have developed a novel cell-sheet manipulation technology using temperature-responsive culture surfaces to generate functional, cultivated corneal epithelial cell sheet grafts. METHODS: Human or rabbit limbal stem cells were cocultured with mitomycin C-treated 3T3 feeder layers on temperature-responsive culture dishes at 37 degrees C. Cell sheets were harvested from the dishes after 2 weeks by reducing temperature to 20 degrees C. Histologic analyses, immunoblotting, and colony-forming assay were performed to characterize the cell sheets. Autologous transplantation was undertaken to reconstruct the corneal surfaces of rabbits with experimentally induced limbal stem cell deficiencies. RESULTS: Multilayered corneal epithelial sheets were harvested intact simply by reducing the temperature, without the use of proteases. Cell-cell junctions and extracellular matrix on the basal side of the sheet, critical to sheet integrity and function, remained intact. A viable population of corneal progenitor cells, close in number to that originally seeded, was found in the sheets. Harvested sheets were easily manipulated, transplantable without any carriers, and readily adhesive to corneal stroma so that suturing was not required. Corneal surface reconstruction in rabbits was highly successful. CONCLUSIONS: Cell sheet engineering technology allows us to create intact, transplantable corneal epithelial cell sheets that retain stem cells from limbal stem cells expanded ex vivo. Our research indicates highly promising clinical capabilities for our bioengineered corneal epithelial sheet.

Validation of Na,K-ATPase pump function of corneal endothelial cells for corneal regenerative medicine.

Tissue-engineering approaches to cultivate corneal endothelial cells (CECs) or induce CECs from stem cells are under investigation for the treatment of endothelial dysfunction. Before clinical application, a validation method to determine the quality of these cells is required. In this study, we quantified the endothelial pump function required for maintaining the corneal thickness using rabbit CECs (RCECs) and a human CEC line (B4G12). The potential difference of RCECs cultured on a permeable polyester membrane (Snapwell), B4G12 cells on Snapwell, or B4G12 cells on a collagen membrane (CM6) was measured by an Ussing chamber system, and the effect of different concentrations of ouabain (Na,K-ATPase specific inhibitor) was obtained. A mathematical equation derived from the concentration curve revealed that 2 mM ouabain decreases pump function of RCECs to 1.0 mV, and 0.6 mM ouabain decreases pump function of B4G12 on CM6 to 1.0 mV. Ouabain injection into the anterior chamber of rabbit eyes at a concentration of <2 mM maintained the corneal thickness, while those over 3 mM significantly increased the corneal thickness. B4G12 cell sheets transplanted into rabbit eyes treated with 0.6 mM ouabain maintained the corneal thickness, while 3.5 mM ouabain significantly increased the corneal thickness. Taken together, pump function >1.0 mV is required to maintain the corneal thickness. These results can be used for standardization of CEC pump function and validation of tissue-engineered CEC sheets for clinical use.

Profiling of extracellular matrix and cadherin family gene expression in mouse feeder layer cells: type VI collagen is a candidate molecule inducing the colony formation of epithelial cells.

Mouse 3T3 feeder layer has been utilized for epidermal and corneal epithelial cell culture to promote tissue-like cell stratification. However, the molecular mechanism underlying epithelial-feeder layer interactions remains poorly understood. Here, the feeder layer activity of six different mouse cell lines was examined in terms of the colony-forming efficiency (CFE) of primary limbal epithelial cells, including corneal epithelial stem/progenitor cells. When epithelial cells and feeder layers were separated by culture inserts, the CFE was significantly lower than that of epithelial cells, which were cultured with feeder cells on the same dish surfaces, implying that direct contacts between these cells and/or pericellular extracellular matrix (ECM) deposition by feeder layers have an important role in feeder layer activity. With TaqMan polymerase chain reaction assay, the gene expression of 29 ECM molecules and 32 cadherin family genes was profiled in two highest and two lowest cell lines in the CFE for limbal and oral mucosal epithelial cells. A significant difference in the expression correlated with the CFE was observed in six ECM molecules and four kinds of cadherin family genes. In these results, type VI collagen was confirmed to be able to promote the colony formation of epithelial cells in vitro effectively.

Effectiveness of 1.25 % povidone-iodine combined with topical levofloxacin against conjunctival flora in intravitreal injection.

PURPOSE: To compare the effect of a reduced concentration (1.25 %) of povidone-iodine (PI) eye drops, combined with 0.5 % topical levofloxacin (LVFX), with that of the standard of care (5 % PI) on conjunctival flora before intravitreal injections (IVT). METHODS: A prospective, randomized, single-blind clinical trial. One hundred eyes from 100 patients who underwent IVT were included. Eyes were randomly assigned to two groups and underwent different preparatory procedures before therapeutic IVT. LVFX drops were instilled three times every 5 min and then either 1.25 % PI drops were instilled three times every few minutes in group A or 5 % PI drops were instilled three times every few minutes in group B, the control. Conjunctival flora and the injection needles were collected for culture both before and after preparation. The number of positive cultures, the species isolated, and the minimum inhibitory concentrations (MIC) of the antibiotics were assessed. RESULTS: The pretreatment culture was positive for 45 eyes (86.5 %) in group A (n = 52) and for 37 eyes (77.1 %) in group B (n = 48). After the preparatory procedure, the cultures were positive for 25 eyes (48.1 %) in group A and for 27 eyes (56.3 %) in group B (P = 0.43). After preparation, the number of positive cultures decreased by 46.7 % in group A and by 33.4 % in group B (P = 0.48). No needle samples were contaminated in either group. The most common isolate in both groups after preparation for surgery was Propionibacterium acnes. Among the different antibiotics, vancomycin and oxacillin had the lowest MIC >90 for overall isolates. CONCLUSIONS: 1.25 % PI with LVFX is as effective as 5 % PI. P. acnes was the most common conjunctival flora detected. Vancomycin has been confirmed as the best choice for treating infectious endophthalmitis after IVT.

Successful outcomes of 25- and 23-gauge vitrectomies for giant retinal tear detachments.

BACKGROUND AND OBJECTIVE: The authors examined the feasibility of performing 25- and 23-gauge micro-incision vitrectomy surgery (MIVS) for a giant retinal tear. PATIENTS AND METHODS: The medical records of 12 eyes of 11 patients with giant retinal tear who underwent MIVS using perfluorocarbon liquids were reviewed. All patients were observed for at least 6 months postoperatively. RESULTS: An intraoperative re-attachment was achieved in 12 eyes (100%) and 11 eyes (92%) remained attached without intraocular tamponade. Silicone oil was used in 9 of 12 eyes and removed 2 weeks after the initial vitrectomy except in one eye. The postoperative retinal complications included macular pucker in two eyes, subretinal perfluorocarbon liquid in two eyes, retinal folds in one eye, cystoid macular edema in one eye, and redetachment due to proliferative vitreoretinopathy in one eye. CONCLUSION: Although the study had a short follow-up period, primary MIVS appears to be safe and feasible for giant retinal tear surgery.

A novel gelatin hydrogel carrier sheet for corneal endothelial transplantation.

We examined the feasibility of using gelatin hydrogels as carrier sheets for the transplantation of cultivated corneal endothelial cells. The mechanical properties, transparency, and permeability of gelatin hydrogel sheets were compared with those of atelocollagen sheets. Immunohistochemistry (ZO-1, Na(+)/K(+)-ATPase, and N-cadherin), hematoxylin and eosin staining, and scanning electron microscopy were performed to assess the integrity of corneal endothelial cells that were cultured on gelatin hydrogel sheets. The gelatin hydrogel sheets displayed greater transparency, elastic modulus, and albumin permeability compared to those of atelocollagen sheets. The corneal endothelial cells on gelatin hydrogel sheets showed normal expression levels of ZO-1, Na(+)/K(+)-ATPase, and N-cadherin. Hematoxylin and eosin staining revealed the formation of a continuous monolayer of cells attached to the gelatin hydrogel sheet. Scanning electron microscopy observations showed that the corneal endothelial cells were arranged in a regular, mosaic, and polygonal pattern with normal cilia. These results indicate that the gelatin hydrogel sheet is a promising material to transport corneal endothelial cells during transplantation.

Irreversible optical clearing of rabbit dermis for autogenic corneal stroma transplantation.

Tissue engineering and transplantation of autogenic grafts have been widely investigated for solving problems on current allograft treatments (i.g., donor shortage and rejection). However, it is difficult to obtain an autogenic corneal stromal replacement that is composed of transparent, tough, and thick collagen constructs by current cell culture-based tissue engineering. Aim of this study is to develop transparent dermis for an autogenic corneal stroma transplantation. This study examined dehydration at 4-8°C and carbodiimide cross-linking on cloudy rabbit dermis (approx. 1.8%-3.8% light transmittance at 550 nm) for dermis optical clearing. Transparency of dehydrated rabbit dermis was founded to be approx. 37.9%-41.4% at 550 nm. Additional cross-linking treatment on dehydrated dermis prevented from swelling and clouding in saline, and improved its transparency to be 56.9% at 550 nm. Rabbit corneal epithelium was found to regenerate on optically cleared dermis in vitro. Furthermore, no abnormal biological response (i.e., inflammation, vascularization, and the barrier defect of epithelia) or no optical functional change on optically cleared dermis was observed during its 4-week autogenic transplantation into rabbit corneal stromal pocket.

Transparent, tough collagen laminates prepared by oriented flow casting, multi-cyclic vitrification and chemical cross-linking.

The lamellar architecture found in many natural fibrous tissues has a significant bearing on their specific functions. However, current engineered tissues have simultaneously no realistic structures and no adequate functions. This study demonstrates a two-step process for obtaining structurally mimicking laminates in natural fibrous tissues with good optical and mechanical characters from purified-clinically-safe collagen molecules. Stacked lamella structures can be created by repeating flow casting, with the controlling parallel/orthogonal directionalities of each thin single-layer (2-5 µm in thickness). The transparency of laminates is successfully improved by a unique multi-cyclic vitrification with chemical cross-linking. The directionalities of optical and mechanical functions in laminates are strongly related with the preferential collagen alignments in the laminates. The tensile strength of laminates is extremely higher than any other engineered materials as well as native cornea, which exhibit an orthogonal laminated collagen structure and a good optical transmission.

Chronic implantation of newly developed suprachoroidal-transretinal stimulation prosthesis in dogs.

PURPOSE: To investigate the feasibility of implanting a newly developed suprachoroidal-transretinal stimulation (STS) prosthesis in dogs and to determine its biocompatibility and stability over a 3-month period. METHODS: The STS prosthesis system consisted of an array of 49 electrodes (nine were active), an intravitreal return electrode, and an extraocular microstimulator. The 49-electrode array was implanted into a scleral pocket of each of three healthy beagle dogs. Color fundus photography, fluorescein angiography, electroretinography, and functional testing of the STS system were performed postoperatively. The dogs were euthanatized 3 months after the implantation, and the retinas were evaluated histologically. RESULTS: All the prostheses were successfully implanted without complications, and no serious complications occurred during the 3-month postoperative period. The fixation of the implant was stable throughout the experimental period. Fluorescein angiography showed that the entire retina, including the area on the electrode array, remained well perfused without intraocular inflammation. Electroretinograms recorded from the eyes with the prosthesis did not differ significantly from those recorded from control eyes. Functional testing of the STS system showed that this system performed well for the 3-month experimental period. Histologic evaluations showed good preservation of the retina over the electrode array. CONCLUSIONS: Implantation of a newly developed STS retinal prosthesis into a scleral pocket of beagle dogs is surgically feasible and can be performed without significant damage to the retina or the animal. The biocompatibility and stability of the system were good for the 3-month observation period.