In vitro contractility of avascular corneal wounds in rabbit eyes

Contraction of corneal wounds has been the topic of recent speculation, particularly in reference to regression of corneal flattening following radial keratotomy. In an animal model of corneal wound fibroplasia, we offer the first demonstration of in vitro contractility by avascular corneal wound tissue. Three millimeter diameter full-thickness corneal trephine wounds were made in 17 New Zealand white rabbit eyes. The animals were killed and specimens were extracted 3-4 wk postinjury. Contractile responses of corneal wounds were measured on a microdynagauge force transducer. When exposed to serotonin, epinephrine or norepinephrine corneal wounds showed contractions reaching maximum force of 20-100 mg with a peak response obtained within 5-10 min and persisting several hours. Normal corneas did not respond to any agent. All normal iris muscle specimens contracted to acetylcholine exhibiting peak responses of 30-60 mg of force within 5 sec decaying over the following 10-20 min. This is different from corneal wounds which fail to respond to acetylcholine (P less than 0.005). These data suggest that avascular corneal wounds possess contractile properties.