Abstract
Abstract: :
Purpose: To define the stability of the refractive results after conductive keratoplasty (CK) with cellular responses in a rabbit model. Methods: CK was performed in eight eyes of New Zealand albino rabbits. On each eye, 24 spots were placed in a cross–corneal manner using three optical zones at 6, 7, and 8 mm. Eyes were monitored by corneal topography weekly. Rabbits were humanely euthanized at 2, 4, 6, or 8 weeks postoperatively. The eyes were then enucleated and processed for histopathology, TUNEL staining and immunohistochemical analysis using antibodies against <font face="symbol">"</font>–smooth muscle actin (<font face="symbol">"</font>–SMA), chondroitin sulfate, and collagen III. Results: All eyes showed an initial mean steepening of the corneal curvature of 2.07 diopters (D) at 2 weeks postoperatively. Corneal topography revealed a 23%, 37%, and 42% regression of the refractive results at 4, 6, and 8 weeks postoperatively, respectively. Immunohistochemical analysis showed evidence of keratocyte apoptosis, myofibroblast transformation, and up–regulation of chondroitin sulfate and collagen III in the area surrounding the tip in each spot. The percentage of positive <font face="symbol">"</font>–SMA in the area of CK was 5.4% at 2 weeks and decreased to 1.65% at 8 weeks. The up–regulation of myofibroblasts had a high correlation with the refractive results and with the short–term stability of the procedure. Conclusions: The histologic changes that occur after CK may be responsible for the regression observed, and the maintenance of myofibroblasts over time may be associated with better long–term stability.
Keywords: refractive surgery: other technologies • hyperopia • cornea: stroma and keratocytes