EFFECT OF ALPHA-CHYMOTRYPSIN ON BREAKING STRENGTH AND ULTRASTRUCTURALMORPHOLOGY OF CANINE CILIARY ZONULES

Objective-To determine the effect of alpha-chymotrypsin treatment on b reaking strength and ultrastructural morphology of canine ciliary zonu les. Sample Population-Eyes from young random-source dogs from an anim al shelter. Procedure-Eyes were obtained immediately alter euthanasia of dogs. The enzyme alpha-chymotrypsin was applied to the ciliary zonu les of 1 eye of each dog; the other eye was treated with saline soluti on as a control. The breaking strength of ciliary zonules was measured , using a linear actuator and force transducer. The lenses and ciliary bodies were then analyzed by scanning and transmission electron micro scopy. Results-alpha-Chymotrypsin reduced the breaking strength of cil iary zonules by a mean +/- SD 44 (+/- 20)%, compared with that for sal ine-treated control eyes. increasing the volume of enzyme further decr eased the breaking strength of the zonules. Differences in the appeara nce of the ciliary body by electron microscopy were not apparent betwe en enzyme- and saline-treated specimens. Conclusions and Clinical Rele vance-Application of alpha-chymotrypsin to enucleated canine eyes at a concentration used in people significantly reduces the breaking stren gth of canine ciliary zonules without any apparent damage to the cilia ry body. alpha-Chymotrypsin may be useful in the removal of subluxated canine lenses and in removal of cataractous lenses in young dogs, in which phacoemulsification often results in appreciable post operative capsular opacification.