[Corneal trophism and sensitivity changes after penetrating keratoplasty].

OBJECTIVE

To evaluate in the rabbit eye the changes in mechanical sensitivity and trophic function of the corneal epithelium after the denervation consecutive to circular trephinations of the peripheral cornea, similar to those produced by penetrating keratoplasty.

METHODS

Complete trephination (8 mm diameter) with rotation of corneal button (PK) was performed in 12 eyes. Non-penetrating trephination, affecting 2/3 of the corneal depth, was made in a group of 12 eyes (NPK). A separate group of 16 nonoperated eyes served as control. Mechanical corneal sensitivity was measured with the Cochet-Bonnet esthesiometer (No. 12 filament). Trophic function of the corneal epithelium was assessed by determining the healing rate of epithelial wounds performed with n-heptanol.

RESULTS

Three months after surgery, sensitivity in the center of the cornea was significantly reduced in both PK and NPK eyes (240+/-0 mg/S and 179+/-20 mg/S, respectively) when compared with control (88+/-10 mg/S, p<0.001). The ability of denervated corneas to regenerate corneal epithelial defects was similar in both, operated and non-operated eyes. Also, no differences were found between PK and NPK eyes.

CONCLUSIONS

Results suggest that three months after corneal graft, throphic maintenance of the epithelium remains unaffected in spite of the significant hypoesthesia recorded at this time. Further experiments are needed to analyze the interaction between corneal epithelial cells and the trigeminal neurons innervating the cornea