Animal model of corneal ectasia in rabbits by intrastromal injection of type II collagenase

INTRODUCTION

Collagenase II has been used to induce experimental keratoconus in animal models. However, its effect when administered by intrastromal injection has not been studied, so the purpose of this study was to study the effects of intrastromal injection of collagenase II on corneal surface and corneal morphology.

METHODS

Six New Zealand rabbits were used, collagenase II was administered by intrastromal injection (5μL of 2.5mg/mL) in the right eyes and balanced salt solution in the left eyes. Keratometry was performed to evaluate curvature alteration, also at day 7 corneas were obtained and Hematoxylin-Eosin staining was performed to examine morphologic changes. Likewise, changes in type I collagen expression were investigated by Sirius Red staining and semiquantitative PCR.

RESULTS

K1, K2 and Km presented differences in the means with statistically significant changes. The morphological changes that were demonstrated were degradation and irregular arrangement of the corneal stroma, increase in the cellular density of keratocytes and slight cellular infiltration. Finally, it was demonstrated that there is greater expression of type I collagen fibers in the experimental group as opposed to the controls and the thickness of the fibers also increased due to the action of collagenase II, however, in terms of genetics there were no changes in the expression of type I collagen at molecular level between the control and experimental groups.

CONCLUSIONS

Collagenase II administered by intrastromal injection is able to induce changes in the corneal surface and stroma, being able to simulate a model of keratoconus.

Ocular Tolerability and Immune Response to Corneal Intrastromal AAV-IDUA Gene Therapy in New Zealand White Rabbits

The chronic ocular toxicity, tolerability, and inflammation following corneal intrastromal injection of saline or escalating doses of an adeno-associated virus (AAV) containing a codon-optimized α-l-iduronidase (AAV-opt-IDUA) expression cassette were evaluated in New Zealand White rabbits. Corneal opacity following corneal intrastromal injection resolved by 24 h. Mild elevation of clinical ocular inflammation was observed 24 h after injection, but it returned to baseline by day 7 and no abnormalities were noted through 6 months of observation after injection. Vector genomes and IDUA cDNA were detected in the injected corneas in a dose-dependent manner. Both the lowest administered AAV-opt-IDUA dose, shown to be effective in mucopolysaccharidosis type I (MPS I) dogs, and a 10-fold higher dose of AAV-opt-IDUA resulted in no detectable immunologic response or adverse effect in rabbits. Vector genomes outside of the eye were rarely detected following corneal intrastromal injection of AAV-opt-IDUA, and neutralizing antibodies to the AAV capsid were not present at the experimental conclusion. This study, combined with our previous studies in MPS I dogs, suggests that AAV-opt-IDUA corneal gene therapy following corneal intrastromal injection of AAV-opt-IDUA has the potential to prevent and reverse blindness in MPS I patients in a safe and effective manner.

Intrastromal injection of voriconazole as a therapeutic of fungal hypopyon: a case report

We describe the case of a 7-year-old child, victim of ocular trauma causing a corneal wound that was sutured urgently. The child has been regularly monitored in our department. Few months later, he consults for a painful red eye evolving within two weeks. The use of voriconazole as an intracameral injection has shown its superiority in treating fungal endophtalmitis. Further studies should be underwent to learn more about better injection strategies and so as to consider better its benefits and side effects.

Preparation and Administration of Adeno-associated Virus Vectors for Corneal Gene Delivery

Gene delivery approaches using adeno-associated virus (AAV) vectors are currently the preferred method for human gene therapy applications and have demonstrated success in clinical trials for a diverse set of diseases including retinal blindness. To date, no clinical trials using AAV gene therapy in the anterior eye have been initiated; however, corneal gene delivery appears to be an attractive approach for treating both corneal and ocular surface diseases. Multiple preclinical studies by our lab and others have demonstrated efficient AAV vector-mediated gene delivery to the cornea for immunomodulation, anti-vascularization, and enzyme supplementation. Interestingly, the route of AAV vector administration and nuances such as administered volume influence vector tropism and transduction efficiency. In this chapter, a detailed protocol for AAV vector production and specific approaches for AAV-mediated gene transfer to the cornea via subconjunctival and intrastromal injections are described.

[Management of corneal neovascularization prior to corneal transplantation: Report of 112 cases]

INTRODUCTION

The avascular nature of the cornea results from a balance between angiogenic factors and anti-angiogenic factors. Under pathological conditions, this homeostasis can be disturbed, resulting in the onset of corneal neovascularization. The purpose of our study was to report our experience in the management of corneal neovascularization prior to keratoplasty.

MATERIALS AND METHODS

This is a prospective study of 112 patients with corneal neovascularization and candidates for possible corneal transplant.

RESULTS

The average age of patients was 38 years, ranging from 15 to 72 years. The etiologies of neovascularization were dominated by ocular trauma (26.8 %). In total, 48.33 % of patients had superficial neovascularization, 18.52 % moderately deep and 33.2 % deep neovascularization. All patients received topical corticosteroids, 29.4 % received subconjunctival injections of bevacizumab, and 22.32 % intrastromal bevacizumab injections. Clinical course was marked by a decrease in the percentage of corneal neovascularization compared to the total corneal surface area, from 45 % (between 16 and 82 %) to 28 % (between 0 and 69 %) at Day 120. There was no statistically significant improvement in visual acuity.

DISCUSSION

Corneal neovascularization is a major risk factor for graft rejection; its management is crucial prior to every keratoplasty.

CONCLUSION

Corneal neovascularization can lead to increased risk of graft rejection. Proper management increases the success rate of penetrating keratoplasty.