In vitro measurement of contractile force of transvitreal membranes formed after penetrating ocular injury

M. Kirmani and S. J. Ryan

We adapted a preloaded isometric microstrain gauge force transducer system to measure in vitro the contractile strength of intravitreal fibrocellular membranes formed after reproducible posterior penetrating injury to the eye. We demonstrated that these intravitreal membranes reversibly contracted to serotonin, norepinephrine bitartrate, angiotensin II, prostaglandin F1 alpha, bradykinin, and vasopressin as well as when placed in a depolarizing solution or if electrically stimulated. The membranes could be subsequently relaxed with papaverine hydrochloride, cytochalasin B, and diltiazem hydrochloride. We further demonstrated adrenergic receptor sites on these membranes. We were unable, however, to demonstrate any response to histamine or acetylcholine. Based on these findings, we postulate that the intravitreal membranes formed after perforating ocular injuries bear a functional similarity to smooth muscle and the contractile tissue formed after injury elsewhere. These membranes are of basic importance in the pathogenesis of traction retinal detachment.