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Our objective was to determine whether key properties of extracellular matrix (ECM) macromolecules can be replicated within tissue-engineered biosynthetic matrices to influence cellular properties and behavior. To achieve this, hydrated collagen and Nisopropylacrylamide copolymer-based ECMs were fabricated and tested on a corneal model. The structural and immunological simplicity of the cornea and importance of its extensive innervation for optimal functioning makes it an ideal test model. In addition, corneal failure is a clinically significant problem. Matrices were therefore designed to have the optical clarity and the proper dimensions, curvature, and biomechanical properties for use as corneal tissue replacements in transplantation. In vitro studies demonstrated that grafting of the laminin adhesion pentapeptide motif, YIGSR, to the hydrogels promoted epithelial stratification and neurite in-growth. Implants into pigs' corneas demonstrated successful in vivo regeneration of host corneal epithelium, stroma, and nerves. In particular, functional nerves were observed to rapidly regenerate in implants. By comparison, nerve regeneration in allograft controls was too slow to be observed during the experimental period, consistent with the behavior of human cornea transplants. Other corneal substitutes have been produced and tested, but here we report an implantable matrix that performs as a physiologically functional tissue substitute and not simply as a prosthetic device. These biosynthetic ECM replacements should have applicability to many areas of tissue engineering and regenerative medicine, especially where nerve function is required.regenerative medicine ͉ tissue engineering ͉ cornea ͉ implantation ͉ innervation

ABSTRACT.Purpose: Intravitreal injections are used extensively to treat retinal diseases. Performing an intravitreal injection increases intraocular volume by the amount of fluid brought into the eye. Whether this influences intraocular pressure (IOP) was investigated here. Methods: A biomechanical model relying on 3-dimensional elasticity theory was developed to determine the short-term effect of volume changes on IOP. We calculated the effect for intravitreal injections of 0.1 ml in myopic, emmetropic and hyperopic eyes. Our calculations were compared with IOP measurements obtained immediately after intravitreal injection of 4 mg triamcinolone in 0.1 ml solution (IVTA) in 22 patients. Shortly after the measurement had been taken, IOP was reduced by paracentesis. Results: Immediately after IVTA, measured IOP was elevated by a mean of 40.6 ± 12.1 mmHg compared with initial pressure (p < 0.001). Measured and calculated IOP were comparable. Eyes with shorter axial length had higher IOP immediately after the injection (p < 0.05). Conclusions: The effect of injected volumes on IOP can be calculated with a biomechanical model. Our results show that paracentesis might be recommended when injecting 0.1 ml of a substance to avoid a short-term increase in IOP. As intravitreal injections are mostly applied in diseases that are due to vascular compromise, it might be prudent not to impair perfusion in those eyes, even for short periods of time.

The blue-light-filtering IOL with a yellow chromophore had no effect on contrast vision and visual acuity. However, the impairment of color perception for blue was statistically significant. The impairment of the blue perception did not exceed the normal range or induce subjective disturbance of color vision.