Effect of iridocryothermy in the normal dog

The base and pupillary zones of the iris were exposed for 10 s to a -79 C cryoprobe (iridocryothermy). The resultant iritis lasted 7 to 10 days as evidenced by aqueous flare, hypotony, and miosis. At 21 days, the iris was depigmented and had an irregular pupil. The initial histopathologic changes after iridocryothermy were iridic intrastromal hemorrhage, exudation, and neutrophil infiltration. The iridic pigmented epithelium was lyzed, and the melanin granules were liberated into the iridic stroma, posterior, and anterior chambers. Irides frozen at the pupillary zone exhibited sphincter muscle degeneration. By 21 days after iridocryothermy, the irides were depigmented and atrophic.