Effect of indomethacin on aqueous PGE₂ levels in rabbits following ocular trauma

Abstract

Using a highly specific radioimmunoassay, post- traumatic aqueous PGE₂ levels were measured in rabbit eyes treated with topical indomethacin aqueous solution, as well as in untreated eyes. In two groups of ten rabbits each, the surgical trauma consisted of corneoscleral incision (without injury to the iris); one of the two groups received prophylactic treatment (3 days) and therapeutic (21 days) indomethacin treatment. In two other groups of ten rabbits each, corneoscleral incision and iridectomy were performed. One group received indomethacin treatment as described above, while the other group was not treated. Surgery was performed in all 40 right eyes, the left eyes serving as controls. In 20 of the 40 left eyes, indomethacin therapy was applied. In all right and left eyes, aqueous samples were withdrawn 3 days and 21 days postoperatively, and PGE₂ concentrations were determined. The results indicate that 3 days after corneal trauma and 3 days after corneal trauma plus iridectomy, there was a highly significant reduction in the elevated PGE₂ concentrations as a result of indomethacin therapy. On postoperative day 21, indomethacin reduced even further the still slightly elevated aqueous PGE₂ concentrations without, however, completely blocking prostaglandin activity. The latter was observed even in the control animals that were not operated upon; they showed minimal PGE₂ levels in response to corneal puncture on postoperative day 3 for the purpose of drawing aqueous samples. Our study demonstrated that short-term indomethacin therapy has a significant inhibitory effect, but no unequivocal answers were found as to the value of long-term treatment.