ABSTRACT
Artificial corneas have been developed as an alternative to natural donor tissue to replace damaged or diseased corneas. This study was conducted to evaluate the stability and biocompatibility of PHEMA-PMMA [poly (2-hydroxyl methacrylate)-poly (methyl methacrylate)] keratoprostheses in rabbits following penetrating keratoplasty. Sixteen male New Zealand White rabbits aged 16 weeks were divided into three groups. Group I and group II contained six rabbits each, while the control group had four rabbits. Experimental surgery was conducted under general anesthesia. The cornea was penetrated using an 8 mm diameter biopsy punch. In group I (core 5 mm & skirt 3 mm) and group II (core 6 mm & skirt 2 mm), the keratoprosthesis was placed into the recipient full thickness bed and sutured into position with double-layer continuous. In the control group, corneal transplantation using normal allogenic corneal tissue was performed with the same suture method. After four and eight weeks, keratoprosthesis devices were evaluated by histopathological analysis of gross lesions. Post-operative complications were observed, such as extrusion and infection in experimental groups. Most corneas were maintained in the defect site by double-layer continuous suture materials for 4 weeks and kept good light transmission. However, most artificial cornea were extruded before 8 weeks. Overall, combined PHEMA and PMMA appears to have sufficient advantages for production of artificial corneas because of its optical transparency, flexibility and other mechanical features. However, the stability and biocompatibility were not sufficient to enable application in humans and animals at the present time using penetrating keratoplasty. Further studies are essential to improve the stability and biocompatibility with or without other types of keratoplasty.
Subject(s)
Animals , Humans , Male , Rabbits , Anesthesia, General , Biopsy , Cornea , Corneal Transplantation , Keratoplasty, Penetrating , Methods , Pliability , Polyhydroxyethyl Methacrylate , Polymethyl Methacrylate , Sutures , Tissue DonorsABSTRACT
AIM: To investigate the biocolonization of poly 2-hydroxyethy methacrylate (PHEMA) sponge with cornea tissue and evaluate the therapeutic effects of modified porous poly 2-hydroxyethy methacrylate-Polymethyl met-hacrylate (PHEMA-PMMA) Keratoprostheses (KPro) on rabbit and monkey corneas. METHODS:The KPro were made using two-stage polymerization combined with mechanical cutting. The experiment was divided into two groups. In the control group, ten normal rabbit eyes received lamellar implanta-tion of PHEMA sponges. The sponges were obtained 2 weeks, 1,2,3 and 4 months after operation. The cell proliferation and neovascularization inside the sponges were observed using light and transmission electron microscopy (TEM) and immunohistochemistry. In the experimental group, the porous PHEMA-PMMA KPros were inserted into the lamellar pockets of eight rabbit corneas and two monkey corneas (stage I operation). The healing process was investigated by slit-lamp microscopy. The anterior lamellar cornea tissues were removed 3 months after surgery, exposing the under-neath transparent core (stage II operation). The operated eyes were then followed up for 3-6 months.light microscope, fibroblasts started to grow into the cornea 2 weeks after operation; lots of cells, accompanied with new blood vessels, invaded into the cornea 2-3 months after surgery. Invading cells of sponge, as well as keratocytes, were positive for vimentin. Under the electron microscope, the invading cells looked healthy and were surrounded by extracellular matrix and collagen. In 8 rabbit eyes which received KPro implantation, anterior lamellar cornea melting happened in two eyes after the stage II operation. The remaining 6 corneas retained their central cores during observation after the stage II operation.Two monkey operated eyes were found no complication thoughout the whole follow-up.cornea. The modified PHEMA-PMMA KPros have obtained a relatively stable results after implantation into animal corneas.