Effects of cyclocryosurgery on the clinically normal canine eye

Four cyclocryosurgical procedures were compared for effects on normal canine eyes. All procedures produced a significant (P less than 0.05) decrease in intraocular pressure, a marked uveitis, ciliary epithelial cell loss, edema and engorgement of the ciliary processes, iris necrosis, protein effusion, chemosis, and mild discomfort, as indicated by mild blepharospasm and slight epiphora. The histopathologic changes were evaluated at 5 minutes, 1 week, 1 month, and 6 months after surgery. The ciliary epithelium was normal in appearance and intraocular pressure had returned to the normal range at 6 months after surgery. The adverse reactions to the cyclocryosurgical procedures included retinal detachments, chemosis, conjunctivitis, transient increased intraocular pressure, uveitis, iris depigmentation, and corneal granulation tissue.