Purpose: To set up an experimental animal model of keratoconus using collagenase type II and evaluate corneal curvature changes.
Methods: 20 mortem New Zealand white rabbit corneas were divided into 4 groups: group 1(15 mg/ml collagenase type II with 15% dextran, N=5), group 2(10 mg/ml collagenase type II with 15% dextran, N=5), group 3(5 mg/ml collagenase type II with 15% dextran, N=5) and group 4(the control group,15% dextran, N=5). After epithelial debridement, corneas were mounted and pressured on artificial anterior chambers,then different kinds of solution was applied to corneas for 1 hour. Corneal curvature was measured before and after collagenase exposure at different intraocular pressure levels(15mmHg, 30mmHg,45mmHg). The results were analyzed statistically.
Results: After exposure, changes of Kmean in group 1,group 2,group 3 and group 4 were 6.33±4.05D, 0.93±1.13D, 0.67±1.66D and -0.26±0.77D respectively at 15mmHg; 5.36±2.39D, 1.49±1.70D, 1.37±2.07D and -0.77±1.11D respectively at 30mmHg; 7.29±3.39D, 2.41±2.37D, 1.47±2.63D and -0.56±1.35D respectively at 45mmHg. Compared to group 4, a statistically significant increase in Kmean across all the intraocular pressure levels was seen in group 1 (p<0.05).However, group 2, group3 and group 4 were not significantly different from group 4(p＞0.05).
Conclusions: 15 mg/ml collagenase type II could induce significant increase in corneal curvature, which might be considered as a method of building the rabbit model of keratoconus.