Tracing local hyaluronan after ocular anterior segment trauma

Hyaluronan has been found in the eye in varying amounts and at different sites. It is involved in physiological and pathological processes, though many aspects of its bio-logi-cal functions are still unclear. We have studied the role of iris tissue in hyal-uro-nan production in the anterior segment of the eye, and its changes after trauma. After peripheral iridectomy or argon laser treatment, the hyaluronan concentration in the iris tissue increased rapidly, reaching a maximum at 1-2 days. It then slowly returned to normal values. The increase was most prominent at the trauma site. Traumatized and normal irides were treated with a radiolabeled precursor to hyaluronan for the demonstration of hyaluronan synthesis in vivo and in vitro. Aqueous humor hyaluronan concentrations followed the changes in iris hyaluronan with the highest values at 1-2 days after iris surgery. Considering the relatively large amount of iris tissue in the anterior segment of the eye and its high hyaluronan content, it seems that the iris is the most important source of aqueous humor hyaluronan. Sympathetic denervation of the eye resulted in a moderate increase in iris and aqueous hyaluronan. It does not seem to influence the iris hyaluronan responses to ocular trauma. Treatment of laser induced iritis with COX-2 inhibitors resulted in a prolonged hyaluronan elevation in the traumatized iris tissue. This is seen also in fetal wounds, which heal without scar formation