A new analysis of wound closure kinematics in the cat and rabbit corneal epithelium

Abstract

Traditional models of the kinematics of corneal epithelial wound closure have been critically reviewed in a recent article by Kwok, who has proposed a new model to overcome previous shortcomings. This model accounts for corneal curvature, and provides for a time-varying velocity of the wound edge. This study applied the model to experimental wound closure in the cat corneal epithelium in vivo. In each cat, 6 mm diameter heptanol wounds were made bilaterally. Timoptol twice daily in one eye had no significant effect on the first-order closure rates of -1.10 ± 0.33 mm2/hr (mean ± SD) in untreated eyes, and -1.08 ± 0.17mm2/hr in the treated eyes (n = 6, P>0.05). The model was able to characterize successfully the non-linearity of wound closure in the cat corneal epithelium, incurring a lower rms error of fit than the first-order analysis. The results indicate that heptanol wounds close at a time-varying velocity. The model predicated that on the corneal surface, wound edge velocity peaks before closure: at 0.15±0.037 mm/hr (range 0.13–0.22 mm/hr) in untreated eyes, and at 0.13±0.022 mm/hr (range 0.085–0.15 mm/hr) in the Timoptol treated eyes. Initial wound enlargement occurred in 3 animals, bilaterally, during which time the model correctly predicted centrifugal velocities. Analysis of data from Ubels et al (J Toxicol-Cut Ocular Toxicol 1:133, 1982) indicates that Richardson's stain impedes wound closure in rabbit corneal epithelium by altering the velocity characteristic of the wound edge. It appears that the new model offers a plausible and effective alternative to traditional kinematic analyses.