Ocular inflammation models by topical application: Croton-oil induced uveitis

Purpose. The aim of the present investigation was to develop a new ocular i nflammation model in the rabbit by comparison of the inflammation response induced by the topical application of several irritating agents (carrageena n, Freund's adjuvant, alkali and croton oil). Methods. The following parameters were determined after the application of each irritant to the eyes of female, white, New Zealand rabbits: Corneal ed ema and the Tyndall effect (slit-lamp biomicroscopy), corneal thickness (bi ometer-pachometer) and aqueous humor levels of the prostaglandin E-2 (R.I.A ), total protein (Weichselbaum technique), albumin, albumin/globulin (Douma s technique) and leukocytes (coulter counter). Results. Croton oil 1-4% (40 mu l) produced edema and a Tyndall which showe d a proportional increase with croton oil concentration. Ultrasonic pachome ter measurement of the variation in corneal thickness (3-168 h) showed a do se-dependent response (p<0.01) from the 8(th) to the 168(th) hour. Uveitis and considerable increases in the levels of the prostaglandin E-2 (4.50 +/- 0.40 pg/0.1 ml vs. 260.03 +/- 2.03 pg/0.1 ml), total protein (0.25 +/- 0.0 5 g/l vs. 2.10 +/- 0.08 g/l), albumin, albumin/globulin and leukocytes were observed in the aqueous humor 24 h after topical application of croton oil 3% (40 mu l). All the values obtained were statistically significant (p<0. 01). Conclusions. The topical application of 3% croton oil (40 mu l) was most ap propriate for the evaluation of the inflammatory process in the anterior ch amber and for the determination of the effects of intraocular penetration. The inflammatory mechanism in this model is thought to involve the activati on of the arachidonic acid pathway accompanied by the breakdown of the bloo d-aqueous barrier permitting high molecular weight proteins to enter the aq ueous humor. Typology: anterior uveitis with corneal edema.