Purpose
To evaluate the clinical, optical and histological changes induced in the corneas of an animal model after implantation of Ferrara intracorneal ring segments (ICRS).
Methods
We performed surgery in 192 eyes of an experimental animal model (Gallus Domesticus). One segment of Ferrara ICRS was implanted in each eye. Clinical evaluation was carried out. Animals with good clinical follow up were randomly separated into groups regarding the time the animal was put down (4, 12 hours, 1, 2, 3, 7 days and 1, 2, 3, 4 and 6 months) and time when they were processed for histological analysis (hematoxilin-eosin and Sudan stain). Quantitative measurements of the hematoxilin-eosin stained preparations were made too. Wound healing process was described due to TUNEL labelling cells (cell death), Brdu inmunofluorescence and the expression of alfa smooth muscle actin (SMA). Transmission electron microscopy of the samples was also done. Optical measurements of the refractive state and direct transmittance of the central cornea were also measured.
Results
79% of the eyes had good clinical follow-up and were used for histological studies. A complete wound healing process was described with cell death from 4 to 72 hours, proliferation of cells from 24 to 48 hours and differentiation into myofibroblast from 1 to 3 months after implantation. Some proliferating cells might originate from limbus. The rotation of the segment may be described as a movement in which the inferior angle next to the limbus approached the epithelium and the other angle increased its distance from the epithelium events which stabilized at 1month. There were no changes in direct transmittance measurements of central cornea. An hyperopic change in refractive state was observed in all eyes.
Conclusions
An experimental animal model of intrastromal corneal ring implantation in hens was developed and characterised by clinical, biophysical and biologic parameters. We have described a complete wound healing process after intrastromal corneal ring implantation similar in stages to those described after PRK and LASIK. However, this wound healing process had some specific features related to the small size of the epithelial and basement membrane damaged and the device permanently implanted inside the cornea.
Keywords: 765 wound healing •
484 cornea: stroma and keratocytes •
574 keratoconus