Patricia Gallego

Differential expression and localization of transient receptor potential vanilloid 1 in rabbit and human eyes

INTRODUCTION The superfamily of transient receptor potential (TRP) cation channels is involved in nociception. Members of this family, such as the vanilloid receptor type 1 (TRPV1) channel, are activated by a wide range of stimuli including heat (⟩43°C), low pH (⟨6.5), hypoxia, and hypertonicity. Here we report TRPV1 expression in rabbit and human eyes. MATERIAL AND METHODS We analyzed the expression of TRPV1 mRNA by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and protein by immunohistochemistry in eyes of New Zealand White rabbits and humans. RESULTS In rabbit and human eyes, TRPV1 protein was present in all layers of the corneal epithelium, but only in the basal layer of the conjunctiva. It was also in the ciliary and lens epithelia of both species as well as in the secretory cells of the rabbit lacrimal gland. The retinal pigment epithelium was positive for this protein in both species. TRPV1 was also present in rabbit Müller cells, where it had a similar pattern of expression to vimentin intermediate filaments. Analysis by qRT-PCR showed that TRPV1 mRNA was found in all of the structures where the protein was present. The highest level was in the lens and the lowest in the retina. CONCLUSION TRPV1 is expressed in cells that are particularly active in Ca²⁺ exchange as well as in cells with significant water transport activity. Because TRPV1 is a Ca²⁺ channel, it probably functions in the regulation of both water and Ca²⁺ movements in ocular tissues.

Scleral changes induced by atropine in chicks as an experimental model of myopia

To determine the effects of intravitreal atropine on scleral growth in the form‐deprived chick as an experimental model of myopia.

Clinical and pathological effects of different acrylic intracorneal ring segments in corneal additive surgery

The objective of this work was to evaluate the potential use of less stiff materials based on acrylic copolymers of methyl methacrylate/2-ethylhexyl acrylate (MMA/EHA) as devices to correct, stabilize and improve the effect of poly(methyl methacrylate) (PMMA) intracorneal ring segments. MMA/EHA and PMMA intracorneal ring segments were surgically implanted in the corneas of Lohmann Classic hens. The effects of the intracorneal ring segments were assessed by optical measurements and corneal tolerance was evaluated through biomicroscopic examination over a 90-day observation period and by conventional histology. The experimental results demonstrated that the intracorneal ring segments made of MMA/EHA copolymers provided a significant change in the corneal curvature and an improved in vivo response compared to those obtained for PMMA rings, which was attributed to the higher flexibility of the copolymeric materials, indicating that these systems might be considered suitable as an alternative to those currently used, for application in clinical practice.

Clinical, Refractive and Histological Reversibility of Corneal Additive Surgery in Deep Stroma in an Animal Model.

ABSTRACT Purpose: The aim was to evaluate the reversibility of the clinical and histological changes induced in the corneas of an animal model after removing an intracorneal ring segment (ICRS). Methods: Surgery for this study was performed in 38 eyes of an experimental animal model (Gallus domesticus) for ICRS surgery (Ferrara technique). The animals without complications were randomized to two groups; in all of them, 1 segment was implanted in each eye and later removed at different times (1 and 3 months after implantation). In each group, after explantation, corneas were processed at different times for histological analysis with hematoxylin and eosin (H&E) stain and electronic microscopy. The refractive state of the eyes was also measured. Results: In corneas without complications (88.23%), explantation was performed correctly. During the first few days, around the area where the ICRS was implanted we observed deposits of cells and a moderate degree of corneal opacity (haze). These signs decreased progressively without disappearing completely. Histologically, at 7 days, we observed hyperplasia and abnormal arrangement of collagen fibers. Later, these findings also decreased in both groups, albeit at a faster rate in group 1. Minimal changes were observed in electron microscopy up to the end of the study in both groups. Preoperative refractive state was achieved at 1 month after explantation in both groups. Conclusions: ICRS can safely be explanted from the cornea. Refractive reversibility was achieved at 1 month after explantation. However, the clinical and histological findings after ICRS explantation depend on the time from implantation to explantation.

Validation of an experimental animal model for corneal additive surgery

Purpose: To assess the hen cornea as a model for training and future wound healing studies after implantation of intrastromal corneal ring segments (ICRS) by clinical and optical outcomes. Setting: University of Valladolid, Valladolid, Spain. Design: Experimental study. Methods: One 90°, 150-μm thick polymethyl methacrylate Ferrara ICRS segment was manually implanted at 70-80% depth of 192 Gallus domesticus corneas. Clinical follow-up for 6 months included monitoring corneal thickness, epithelial wound closure, edema, haze, and the location and severity of deposits. The refractive state was also measured. After each animal was euthanized, corneas were processed for direct transmittance and histological analysis. Results: Complications were present in 16% of the eyes. Epithelial wound closure was completed at 3 ± 2 days. A slight corneal edema in the channel site was present for the first 15 days. All corneas had deposits by 4 months located along the inner, outer curvatures and under the segments. Corneal haze was present only at the incision site. ICRS induced hyperopic changes in the refractive state without changes in direct transmitance of central cornea. New cells and extracellular matrix were present around the segment where deposits were seen on clinical follow-up. Conclusions: With hen as an animal model, ICRS were implanted in a precise and reproducible way after a learning curve. Similar to humans, the follow-up period during the first 6 months after implantation showed fast wound closure, deposits, and haze at the incision site. ICRS in hens also reduced the refractive power without affecting the central cornea.